Sunday, October 10, 2010

New Website at whatgrowsthere.com!

I've been working on my new website, What Grows There and have moved this blog over to that location. All new posts will be there. Enjoy! http://www.whatgrowsthere.com

Saturday, October 9, 2010

New Intersectional Peonies Deserve A Wow!

Photo: tree peony at Staten Island Botanical Gardens
Itoh or Intersectional Hybrid Peonies (Paeonia spp.) represent a huge breakthrough in tissue culture propagation. Inherited from the tree peony is attractive dissected foliage. They are extremely winter hardy like the herbaceous types.


Plants grow two to three feet tall and wide. Strong sturdy stems support the huge flowers which size up to 10" across. Flowers are single, semi-double or double, and available in a wide range of colors including yellow. Flowers stand upright even in heavy rain and require no staking. Bloom time is longer due to additional flowers being produced on side shoots.

Peonies are long-lived, growing in the same location for decades. They need to be properly nourished annually. Peonies prefer full to part sun (minimum of 6 hours per day), average moisture and well-drained soil which is enriched with compost or mulch annually.

Bare-root peonies should only be planted in the fall as this coincides with the time that their tubers develop most of their feeder roots. Container-grown peonies can be planted at any time. Itoh hybrids demonstrate good resistance to peony blight (Botrytis paeoniae).

Proper planting depth is very important for peonies. The crown should be planted 1½ - 2 inches below soil level. If the eyes have already begun to grow, the new growth may be set slightly above the surface.

Itoh peonies are now available through e-commerce nurseries.

Wednesday, October 6, 2010

Tips on Planting Peonies

Peonies (herbaceous types) are old-fashioned perennial favorites garnering new attention from 21st century gardeners. Their gorgeous spring flowers stand tall above the lush shrubbery growth.

This fall, plant dormant bare-root divisions of herbaceous peonies purchased from a mail-order nursery or a nearby garden center. Each division must exhibit 3 to 5 eyes (buds). Space plants a minimum of three feet apart.

Good air circulation around plants is important to prevent potential foliar and flower diseases. Avoid windy areas and shelter plants from harsh summer sun and heat in warmer climates (USDA zones 7-9).

Peonies thrive in gardens for 20 or more years. Select a sunny spot with well-drained garden soil and enrich with generous amounts of compost or well-rotted manure. A soil pH between 6 and 7 is ideal. Feed peonies with a slow release fertilizer in early spring the same as you would nourish flowering shrubs.

A critical digging step is the planting depth. Do not cover the growing eyes with more than 1 inch of soil. Setting the new plant too deep may delay or even prevent flowering. Water the newly planted peonies and cover the bed with 2-3 inches of loose ground up leaves or bark mulch. Likely, the peonies will bloom next spring and many years thereafter.

Tree peony culture will be discussed in a future blog.

Sunday, October 3, 2010

Goldenrod --Set Off Some Fireworks This Fall

Rough-stemmed goldenrod (Solidago rugosa) grows in low woods, meadows and bogs in the eastern half of North America.. ‘Fireworks’ (USDA zones 4–8) has a more compact plant habit than the species. This early blooming cultivar provides a long floral show starting in mid-August and lasting thru Thanksgiving, weather permitting.

Flowers spikes are numerous and held in tight clusters on upright stems. The yellow, thread-like, cascading sprays of flowers do attracts many insect pollinators; the pollen does not cause allergies as once believed.

Goldenrods grow best in full sun to light shade. While they prefer moist, well-drained, slightly acidic soil, established plants flourish in hot, humid and dry summers. Surprisingly, goldenrod tends to grow weak lateral shoots in soils that are organically rich.

'Fireworks' spreads quickly by seed and underground rhizomes and needs to be divide every 2-3 years . This upright herbaceous perennial grows 3 - 4 feet tall and 2 – 2.5 feet wide. Remove old flowers to encourage re-blooming. Deadhead or remove spent blooms on 'Fireworks' to generate added lateral floral sprays into late October and November. Removal of seed heads reduces re-seeding threat.

Thursday, September 30, 2010

Fall Planting Deadline for Pansies and Violas

To grow pansies successfully, follow this four- step program. Start with: 1. Purchasing healthy plants, 2. Planting by mid-October or earlier, 3. Watering in the fall and winter as needed, and 4. Fertilizing monthly through the winter and spring months.

Shop for vigorous dark green plants at local greenhouses and garden centers. Closely inspect for lots of white growing roots. Don’t buy short or spindly seedlings or those with yellowing leaves. Purchase sturdy 1801 plants (18 - 3 ½” plant cells per tray) or larger pots. Small pansies tend to be more disease susceptible. To avoid deadly root rot diseases in garden soils, move pansy/viola beds every three years.

Over much of the Southern Appalachian region (USDA zones 6-7), the completion date for planting pansies and violas is October 15th. Back up a week or two earlier if planting in gardens at higher elevations. An earlier fall planting date allows plants adequate time to root down into the warm autumn soil. Deeply rooted plants bloom heavier through the fall and winter seasons.

Large sized plants start off quickly and fall-winter flowering is better. Deeply rooted pansies and violas provide better anchorage, which prevents a chance of winter freeze heaving. Once soil temperatures drop below 45°F, plant growth slows and flower numbers decline.

There are many series of pansies and violas to choose in colors ranging from white, yellow, pink, red, and purple shades. Color patterns may be clear, blotched or picotee. Four popular pansy series are Delta®, Matrix®, Panola®, and Majestic Giant ll™. Among the popular viola series are Sorbet®, Rocky™, Penny™ and Velour™.

Prepare the garden bed or containers prior to planting. Pansies should be planted in well-drained, organically rich garden soil or container media mix. An acidic soil pH ranging between 5.2 - 5.8 avoids natural deficiencies in iron and manganese. Adding lime to pansy beds is usually unnecessary unless recommended after a soil test. Pansies thrive in full sun to partial shade. Plants grow more compact and bloom heaviest in full sun.

Monday, September 27, 2010

Franklinia - Native Tree Lost in the Wild

Franklinia (Franklinia alatamaha) is a wonderful small tree or large multi-trunked shrub with fragrant white camellia- like flowers. Franklinia is related to world-class flowering shrubs like camellia and stewartia. Its white 3 - 3 ½ inch camellia-like flowers appear from early August thru late September.

Franklinia is winter hardy in the Southern Appalachian region (USDA zones 6-7). Its fibrous root system prefers a well-drained, richly organic, and acidic soil much like azaleas and rhododendrons. Don’t subject to extended summer droughts or frigid drying winter winds.

Fall color is respectable with autumnal hues of red, orange and burgundy. The bark on a young tree is distinctively striped, and the main branches become fissured with age.

The species was discovered by plant explorer John Bartram and his son William growing along the Alatamaha River in southeastern Georgia in 1765. Natural populations are now extinct. All franklinia trees growing today are descendants of the Bartrams’ collected seeds.

Franklinia is a finicky grower, but very much worth the challenge. A deadly fungal root disease, Phytophthora cinnamoni, may have led to its demise in nature, is its Achilles’ heel. A 2-3 week long invasion of Japanese beetles in August may shorten individual bloom life by half.

Saturday, September 25, 2010

Substitute Dwarf Cryptomeria for Yews and Japanese Holly


For better garden performance and different textural look around a home foundation, plant the dwarf shrub forms of Japanese cedar (Cryptomeria japonica). Dwarf cryptomeria is an excellent substitute for Japanese yews (Taxus spp.) or 'Helleri' hollies (Ilex crenata) which often struggle in heavy clay soils, particularly those poorly drained.

'Globosa Nana' (photo) has a "cookie-cutter" round, globular form, and rarely needs pruning. 'Globosa Nana' has bright green floiage and grows 3-6 feet tall and wide. The cultivar 'Black Dragon' has dark green foliage and a pyramidal growth habit (8-12 feet tall and 4-5 feet wide). Both are planted as single specimens or grouped several together They are slower growing than their taller 40-50 feet columnar counterparts.

Cryptomerias prefer well-drained, slightly acidic soil and are planted in an open sunny location. Young shrubs are remarkably shade tolerant. Their dark evergreen foliage turns a bronze to purple color during the coldest part of winter. By early spring the bright or dark green color returns to their short needles. Fertilize shrubs annually either in February or March.

Garden centers sell either balled and burlapped (b&b) or container-grown stock. Cryptomeria is best planted from February thru October. This evergreen demonstrates superior heat and drought tolerances once established in the landscape for two years.

Wednesday, September 22, 2010

Truly, Fall Is For Planting

Photo: Fall displays have arrived at area garden centers with this lovely bin of gourds

The seasonal theme at garden centers today is "Fall is for Planting". Plant sales are everywhere. If you have recently purchased a home and your budget is tight, buy yourself an early, but practicable holiday gift- a deciduous shade tree planted along the southwest side of the home. In a few short years, this tree will reward you with valuable shade and lower summer cooling bills.

Some good deciduous choices are red maple, green ash, tulip poplar, sweetgum, willow oak, and basswood. Garden centers push to reduce store inventories, saving you 30%-50% off the list price. I offer these six basic landscape planting tips:

1. Plant only deciduous trees in the front of your home, and evergreen trees (pines, hollies, hemlock, etc.) elsewhere
2. Dig a hole three times wider and shallow enough to accomodate the diameter of the root ball
3. Plant shallow, barely covering the root ball and add no soil amendments
4. Apply three inches of an organic mulch (wood chips, pine straw or compost) over the surface
width of the planting hole and do not pile mulch up against the trunk
5. Slowly pour a minimum of 10 gallons of water to each tree after planting
6. Do not fertilize fall-planted trees and shrubs until late February or March.

Sunday, September 19, 2010

Ivy Geranium 'Lila Compact'

Ivy-leaf geraniums (Pelargonium peltatum) owe their name to their leaf shape. While zonal geraniums are favorites in garden beds, the vining or cascading ivy geraniums excel in hanging baskets, containers and window boxes.

Earlier this month I spotted this lavender beauty called ‘Lila Compact’ Cascade™ (photo) in downtown Asheville, NC. City grounds crews have hand-watered all plants over a 5-6 block area every morning since mid-May.

Improved modern cultivars exhibit better heat and drought tolerances than in the past. Newer cascading varieties of ivy geraniums are also more floriferous. Ivy-leaf geraniums grow best in cool climates and lots of sun. They handle 85°F summer temperatures for short stretches. In warmer areas of zone 7, place containers in partially shaded exposures. Ivy leaf geraniums don’t hold up to long periods of drought. They are planted outdoors after threats of spring frosts have passed and the soil/media has warmed up.

The single flowering types produce more blooms than the semi-double flowering varieties. Plants hold their compact form throughout the summer months. Many colorful varieties are available -- from 12” sized miniatures to the vigorous 4- 5 feet cascading types highlighted here.

Wednesday, September 15, 2010

Coppicing - Renewal Pruning for Old Rhododendrons

Photo: when rosebay rhododendron (R. maximum) gets too tall and leggy, coppice (prune back) in late September and October

Coppicing is a no-brainer form of renewal pruning. The entire shrub is lopped off to the ground to re-start from its roots next spring. For many gardeners, it's a gutsy move, but a fairly simple task. Coppicing also eliminates disease and/or insect- riddled stems and twigs without resorting to pesticides.

Timing is critical. Overgrown rhododendrons, including deciduous azaleas, hollies, pieris and mountain laurels may be coppiced from late September thru October. Coppicing invigorates old shrubs, brightens foliage color and increases fruit size.
Very important: over-grown shrubs should be well-established and healthy; old rhodies in poor health will likely not re-grow. Rhodies may be cut back severely to stumps with no leaves. Healthy plants recover quickly vegetatively, but do not flower for two, sometimes three years.
A coppiced plant sometimes re-grow so vigorously that some additional pruning will be necessary. Many new shoots (stems) will emerge; select the most straightest and most vigorous.

Hand clippers, loppers, and saws should be sharp. Do not use weed-eaters.

Saturday, September 11, 2010

Rooting Proliferations on Daylilies

Photo: daylily proliferations on old floral scape in late August

Proliferations are small plants which grow on the spent floral scapes of daylilies (Hemerocallus spp.). Not all daylily varieties produce proliferations. Propagating and growing proliferations is a simple way to increase the number of new daylily plants quickly.
Prune off each plantlet from the old floral scape as they form. Stick each one into a prepared ground bed. Label or tag the cultivar from which the proliferation is taken. Over the next two weeks, keep the soil/media moist. The proliferations will expand their roots into the media.
An alternative approach is to set each proliferation into its own 4-6 inch pot containing coarse sand or soil-less media or mix. Keep the media moist and grow new daylily plant into late fall. If you live in a cold winter (USDA zone 6 and colder), bury the pot to prevent serious freeze injury or grow in a protected cold frame. In areas experiencing mild winters (USDA zones 7 and warmer), transplant newly rooted plants into a ground bed before November 1st.
Plantlets should begin flowering within 18-24 months. If, in haste, you had removed the old floral scapes after spring bloom, don't be in quite a hurry next summer.

Wednesday, September 8, 2010

Fall Blooming Perennials

Photo: Fall anemone 'Honorine Jobert'

The end of summer does not mean that other perennials aren't beginning their blooming season. Three fall flowering perennials- reblooming daylilies, remontant iris, and fall anemones- thrive here in the Southern Appalachian (USDA zones 6 and 7).

Early fall is a great time to again enjoy a lovely bed of re-blooming daylilies (Hemerocallus spp.). 'Stella D'Oro' (golden yellow), the most popular variety for the past quarter of the century, was recently dethroned by 'Happy Returns' (light yellow). 'Pardon Me' (red) is another re-blooming favorite. Inter-planting daffodils, tulips or hyacinths among the daylily clumps extends your floral calendar another month or two.

Remontant iris (Iris spp.) re-bloom a second time from August through November. The trick to re-blooming daylilies and irises is to provide some relief from summer drought stress. Weekly deep watering is certain guarantee of repeat fall bloom.

Fall anemones (Anemone x hybrida) are available in many colorful varieties, starting with an old favorite and garden performer 'Honorine Jobert' (2-3 " single white blooms), 'Queen Charlotte' (3" semi-double pink), 'September Charm' (3" single rose-pink), and 'Whirlwind' (4" semi-double white).

Do not grow fall anemones in direct full day sun. Plants prefer a partial sun to partial shady spot. Caution: plant in spring thru mid-summer to permit adequate time to establish their roots. Anemones perennialize easily when planted in richly composted, well-drained garden soil.

Friday, September 3, 2010

'Sunshine Daydream' Helianthus for Mid-Summer Bloom

Sunshine Daydream (Helianthus x multiflorus ‘Sunshine Daydream’) has been blooming non-stop in my Northeast Tennessee garden for the past two months.

This double-flowering yellow false sunflower is a new introduction from North Creek Nurseries, a wholesale nursery in Landenberg, PA. Sunshine Daydream is a branch sport (mutation) of native cultivar ‘Capenoch Star’. It is a mid-summer flowering perennial.

Sturdy 5 - 6 feet tall by 2 - 4 feet wide plants support bouquets of bright yellow double flowers. The dahlia-like blooms measure 2.5 inches across. The spent flowers are seedless and do not threaten to become a weedy problem in years to come.

Sunshine Daydream performs best in full sun, preferably in moist well-drained soil. Keep plants in full vigor with monthly applications of a water-soluble fertilizer such as Miracle -Gro™ or equivalent or feed bi-monthly with 10-10-10 or equivalent.

Sunshine Daydream stands up to summer's heat and humidity. Established 1- year old plants are moderately drought tolerant. This long-lived perennial is hardy in USDA zones 4 thru 8. The summer foliage of Sunshine Daydream is remarkably resistant to powdery mildew, a fungal disease which plagues some helianthus species.

Tuesday, August 31, 2010

Potential Epidemic In Your Car Trunk Or Camper?

Photo: walnut twig beetle infestation

Tennessee Department of Agriculture (TDA) officials urge state residents and visitors to the state to help prevent the spread of Thousand Cankers Disease in black walnut (Juglans nigra)trees and Emerald Ash Borer in ash species (Fraxinus spp.). Take the following steps:

 Don’t transport firewood, even within Tennessee. Don’t bring firewood along for camping trips. Buy the wood you need from a local source. Don’t bring wood home with you.

 Don’t buy or move firewood from outside the state. If someone comes to your door selling firewood, ask them about the source, and don’t buy wood from outside the state.

 Watch for signs of walnut twig beetle infestation in your black walnut trees. If you suspect your black walnut tree is infested with TCD, visit www.TN.gov/agriculture/tcd for an online symptoms checklist and report form or call TDA’s Regulatory Services Division at 1-800-628-2631.

Sunday, August 29, 2010

Mulching- Not Always a Good Practice

A generation of gardeners have extolled the benefits of mulching around trees and flower beds. Sometimes, mulching is not a good practice.

Often, a heavy clay soil retains too much moisture over the winter months. Some dryland perennials, such as cheddar pinks (dianthus), euphorbia, and delospermum, prefer dry to moderately wet winter soils. Amending with coarse sand improves soil drainage, but adding mulch may be counter-productive.

Quality mulch contains very little cellulose (wood) fiber. A wood based mulch attracts structural wood -feeding insects such as termites, carpenter ants, and wood beetles. Wood-based mulches should not be spread around home foundations.

Fresh wood-based mulch grabs up available soil nitrogen. Nitrogen -starved plants appear yellowed (chlorotic). You may need to apply 2-4 times the amount of fertilizer to counteract the wood mulch.

Piling up mulch around the base of trees, called "mulch volcanoes", will damage tree trunks. Surface roots are deprived of oxygen. Often, weak adventitious roots grow in the mulch. When the mulch dries out, the weak roots die and scar the trunk.

Young fruit trees should not be mulched in the fall and winter where field mice (voles) are suspected. The voles create a home in the mulch and feed on live roots and soft tree bark.

Wednesday, August 25, 2010

Zones 6 Winter Hardy Encore Azaleas™

'Autumn Ruby' Encore azalea in April 2009
Photo credit: Dr. Alan Windham, Extension Plant Pathologist, University of Tennessee

Encore Azaleas™ bloom twice: in the spring and from late summer into the fall season.
Ten varieties consistently exhibited cold hardiness throughout zones 6-a and 6-b: Autumn Amethyst, Autumn Carnation, Autumn Cheer, Autumn Lilac, Autumn Royalty, Autumn Ruby, Autumn Sangria, Autumn Sundance, Autumn Sunset, and Autumn Twist.

In Zone 6-b, nine additional varieties also consistently exhibited exceptional cold hardiness: Autumn Bravo, Autumn Carnival, Autumn Debutante, Autumn Embers , Autumn Empress , Autumn Monarch, Autumn Princess, Autumn Rouge, and Autumn Sweetheart.

For best results in plant zones 6-b and colder, gardeners should plant in the spring or early summer. In Zones 7-9, Encore Azaleas benefit from fall and late summer planting schedules. Their multi-season blooms make them ideal for container gardens.

Encore azaleas™ begin blooming each spring like traditional azaleas. These evergreen azaleas enjoy more sun than traditional azaleas. Encore Azaleas were bred by Robert E. “Buddy” Lee of Independence, Louisiana and are available at many independent garden centers.

Sunday, August 22, 2010

Chinese (Kousa) Dogwood Doesn't Like Extreme Heat

photo: leaf curl on kousa dogwood
Never forget the adage: "the right plant in the right location". In USDA hardiness zone 7 and warmer parts of zone 6-b, Chinese dogwood (Cornus kousa) does not cope with excessive summer heat well. A typical stress response is leaf curling. On more stressful droughty sites, leaf margins and centers will likely burn.

The young tree pictured above is planted along a suburban street, with a concrete sidewalk and street curb on two sides. Thick turf sod covers the ground beneath the tree, competing with the tree for available soil moisture and nutrients. On a hot 90°F day, this tree is likely to experience heat indices above 120°F.

Likely, the tree will survive, but not bloom dependably every spring. Leaf burning and curling reduce the tree’s ability to photosynthesize, resulting in less (or more) flower bud set. The tree will either flower poorly or bloom heavily in future springs, resulting in an alternate flowering cycle or "biennial bearing".

Kousa dogwood will handle full sun locations, provided heat and drought stresses are managed through timely irrigation. Currently, the University of Tennessee is evaluating several seedling kousa selections for better heat and drought tolerances here in the mid-South.

Saturday, August 21, 2010

'Dee Runk' is Best Upright Boxwood



Looking for the best upright boxwood for your garden or landscape? According to wholesale boxwood growers, Saunders Brothers Nursery in Roanoke, VA and Weigel Farms near Greensboro, NC, the best is 'Dee Runk' (pictured).

Over the past quarter century, the boxwood cultivar 'Graham Blandy' had been the standard bearer, but commercial landscapers have increasingly complained about losing plants to pythium and phytophthora root rot diseases. 'Dee Runk' and another called 'Fastigiata' possess better disease resistance. ‘Dee Runk’ is also more reliable than the root rot prone ‘Sky Pencil’ holly (Ilex crenata 'Sky Pencil').

Buxus sempervirens ‘Dee Runk’ is remarkably winter hardy (USDA hardiness zones 5-8). Growth rate is medium, reaching 10 feet in height and 3 feet in width after 15 years. New foliage begins with a bluish-green tint and matures dark green. Boxwoods are deer-resistant and pollution tolerant.

In general, boxwoods tolerate most garden light conditions from full sun or moderate shade at the edge of a woodland garden. ‘Dee Runk’ also handles poor clay sites, provided soils are well-drained.

Landscape uses: specimen, screens/formal hedges, in containers, and a foundation shrub that won’t interfere with roof eaves in future years.

Wednesday, August 18, 2010

Intensia® Phlox Stand Up to Summer Heat

Photo: 'Intensia Lilac Rose'
The Intensia® Phlox series are the result of a cross between P. drummondii and a southwestern U.S. phlox species. Growth is low and cascading which makes this annual phlox ideal for planting in the front garden border. Equally, Intensia® Phlox excel in mixed containers, window boxes, and hanging baskets.

Intensia® phlox grow to a uniform 8-12” mature height in full to partial sun (best in 6 hours or more sunlight). Intensia phlox possess exceptional heat and humidity tolerances and flower freely all summer long. Insect and disease problems are minimal, exhibiting above average powdery mildew resistance.

Annual phlox thrive in well-drained garden soil which has been generously amended with organic matter. After planting, water on a 7-10 day schedule, particularly when rainfall is not plentiful.

By mid-summer plants may appear seedy and overgrown. Mow them back to 5 inches high, add fertilizer, and irrigate. The phlox bed will perk up and re-bloom within a few weeks, and right into the autumn season.

Blooms are slightly fragrance and attract frequent visits from nectar-hungry bees and butterflies.Flower colors of the Intensia® series range from white, several pink shades, lavender, and purple.

Sunday, August 15, 2010

Pruning Big Leaf Hydrangeas

photo credit: Dr. Ken Tilt, Auburn University

When mophead and lacecap hydrangeas (Hydrangea macrophylla) get too tall, leggy, or have outgrown their garden space, prune them now from mid-July thru mid-August. Our native oakleaf hydrangeas (H. quercifolia) are pruned at this time as well. Remove withered or faded flowers; some new flowers may replace those that you have deadheaded in September.

These two hydrangea species set their flower buds for next spring on old or current season’s growth on the terminal bud. Pruning in the fall or winter may remove flower buds or stimulate soft late shoots which die over the winter. Make all cuts at 1/4 inch above the last set of leaves (see photo) or cutback flush to a main branch.

Pruning improves the health of the plant, increasing vegetative growth. On older 4-5 year old hydrangeas, remove larger, thicker canes and prune them at the base of the stem. Remove one-quarter to one-third of these older branches. In 3-4 years the hydrangea will be completely rejuvenated.
Dead, dying, diseased stems and flowers can be removed at any time of year.

Friday, August 13, 2010

A Perfect Year for Hortensia Hydrangeas

2010 has been an exceptional year for big leaf hydrangeas (Hydrangea macrophylla), also called “hortensia” hydrangeas. Consecutive year blooming rarely occurs here in the southern Appalachian region (USDA zones 6 and 7). ‘Nikko Blue” hydrangea, which has not bloomed for over 15 years, has been beautiful in my garden this summer.
Why have big leaf hydrangeas been so “on” this summer? I asked Dr. Sandra Reed, USDA hydrangea breeder at the TN State University Nursery Crops Research Station in McMinnville. Sandra’s response… “the weather”. The 2009 autumn was unusual. October and November temperatures gradually declined. The winter was cold and temps stayed cold, not fluctuating wildly. Across most areas a perfect spring followed with no severe freezes or frosts.
Finally, new hardier cultivars are available such as Endless Summer®, ‘Penny Mac’, and ‘Pia’ (lacecap type). These varieties are remontant, able to bloom on either old or new wood.

If your hydrangea(s) did not bloom this year, check the plant’s light exposure and nutrition. Hortensia types want a minimum of one-half day sunlight, preferably in the morning. Feed shrubs in early spring with a water soluble or slow-release fertilizer according the manufacturer’s package directions.

Wednesday, August 11, 2010

Cardinal Flower – A Hummingbird Magnet

Cardinal flower (Lobelia cardinalis) is a hardy perennial native in USDA zones 5-8. Clumps should be divided every 2-3 years to retain plant vigor. Soil moisture determines its height and vigor.

Cardinal flower prefers half-day direct morning sunlight, particularly in more southern climes. The brilliant red flowers bloom from late July through most of September, making it a standout on their own or mixed with other perennials. Deadheading (pruning off the old floral stems) extends out its flowering period.

Cardinal flower grows 3 feet high and 2 ½ feet wide, and is taller when planted at the edge of a pond or water garden. This lobelia is at home in a rain garden, particularly when summer moisture is plentiful. Fertilize with a water soluble product monthly or feed bi-monthly with agricultural grade fertilizer (10-10-10 or equivalent) from late winter to the end of the flowering period.

Select these two cultivars -- ‘Fried Green Tomatoes’ exhibits bright green foliage which turns a deep olive color on the leaf upper surface and maroon on the underside; flowers are bright red. ‘Monet Moment’ bears exquisite rose-pink flowers. Blooms on both cultivars are exceptionally larger than species.

Sunday, August 8, 2010

Summertime Is Here...So Is Locust Leaf Miner


Photo: 'Freesia' black locust tree
Some trees take on a dead brownish look along highways in the summer months across the southern Appalachian region (USDA zones 6 and 7). Over the past month, locust leaf miner have been feeding on black locust (Robinia pseudoacacia) trees, stripping chlorophyll from the leaves.

Something to worry about? Generally, no. Spraying insecticides is usually not necessary. By late June black locust trees have completed their "photosynthetic life cycle" and foliar injury does not prevent old established trees from starting fresh next spring.

Generally, American gardeners have always had a low opinion about our native black locust. However, new black locust cultivars are awakening our interests. To list three exciting cultivar introductions- try Twisty Baby™ with lacy foliage and twisted shoots, 'Purple Robe’ with dark red-rose flowers, and golden leaved 'Frisia'. These young trees need insect protection.

A time-saving, environmentally safe treatment is a soil application of imidaclopyrid (Bayer Advanced Garden Insecticide™) in early spring. Simply, the pesticide is applied to the ground under the tree and watered in (according to label directions). This prevents beetle larvae development in the spring, and eliminates the threat of the summer leaf skeletonizing adults.

An alternative summer treatment is to spray any pyrethoid insecticide labeled for landscape trees and shrubs. Spraying large trees are a chore, requiring two or more applications over a 4-6 week period.

Thursday, August 5, 2010

'Notify Grounds Crew' Daylily

What's in a name? During our July pilgrimage to Kingwood Center in Mansfield, Ohio, I photographed this unlabelled daylily. It towered over all other daylilies in the large display bed. Of course, my curiosity go the better of me, and I had to know its name.

Mystery solved, thanks to Mr. Charles Applegate, Kingwood gardener for the past 42 years. Charles called me, and provided the pedigree of 'Notify Ground Crew'. What a great name, one that I will not likely to forget.
'Notify Ground Crew" is a mid-season tetraploid bloomer. It exhibits extremely tall 72-inch high floral scapes and is well-branched (see photo). Cheery, 5 inch wide, bright yellow flowers tower above all other daylily varieties in the bed. It was bred by Curt Hanson in Michigan and introduced in 2000. It is very modestly priced and available from several on-line nurseries.

Monday, August 2, 2010

Arkansas Amsonia - 2011 Perennial Plant of the Year

Since 1990, the Perennial Plant Association (PPA) has annually selected one outstanding perennial for gardeners to enjoy. Last week, at the annual PPA Symposium in Portland, OR, members selected Arkansas amsonia (Amsonia hubrichtii) as the 2011 Perennial Plant of the Year.
Why wait until next year to purchase amsonia? It is available now through many garden centers, mail order, and on-line nurseries. Amsonia begins its rapid growth in early April. A month later, the 3 foot tall and wide plants are blooming. Pale “bluestar” flowers bloom over 2-3 weeks in the southern Appalachian region (USDA zones 6 and 7).
Flowering is just a prelude to its other attributes. Blue-green, fine textured summer foliage is devoid of serious disease and insect problems and is deer proof. In October, its foliage turns a spectacular lemony yellow. To achieve maximum autumn foliar impact, plant three or more amsonia spaced 3 to 4 feet apart.
Amsonia forms strong stems under full day sunlight; branches are weak or floppy in partial shade. It grows in any well-drained soil with a pH range from 5.6 -6.8. Established plants are heat, humidity, and drought tolerant.
Furthermore, don’t overlook another perennial favorite, bluestar amsonia (A. tabernaemontana), which will be featured in a future blog.

Sunday, August 1, 2010

Plumleaf Azalea -This Gardener's Choice

Plumleaf azalea (Rhododendron prunifolium) has been blooming in my garden for the past ten days. This species is a late July - early August bloomer in northeast TN. The bright orange-red flowers of this native azalea light up any garden spot whether in full sun or partial shade. Provide some additional shade in southern climes (zones 7-b and 8). A dark red flower selection is available.
It grows in any well-drained soil type- sand, silt or clay. My two established shrubs receive little nutritional care. Shrubs are irrigated during severe drought periods, such as we are in currently.
Plumleaf azalea is an Alabama/southwest Georgia native, but is winter hardy in the southern Appalachian region (USDA zones 6-7), and further north (zone 5). It seems almost soil pH insensitive, although likely prefers an acidic range between 5.4 to 6.4. No diseases and insects pests trouble it. Flowers are not fragrant, but do attract numerous butterfly and bee pollinators.

Pruning is rarely done on my 15+ year old plant purchased at Callaway Gardens. Plumleaf azalea grows 8-10 feet tall, but I maintain it at 6 by 6 feet tall and wide. An errant branch is occasionally clipped back into the fold.

Thursday, July 29, 2010

Thousand Cankers Disease Found in Knoxville, TN

Photo: walnut canker from Dr. Alan Windham, Extension Plant Pathologist, University of Tennessee
A black walnut (Juglans nigra) sample collected by Dr. Scott Schlarbaum, research forester at the University of Tennessee, has been confirmed as thousand cankers disease (TCD) (Geosmithia sp. nov.). Also found in the Knoxville TN walnut sample was one adult male beetle, verified as walnut twig beetle (Pityophthorus juglandis).

This is the first report of the walnut twig beetle and TCD in the native range of black walnut. TCD has killed thousands of walnut trees in the western United States and could potentially be devastating in the eastern United States as well. The extent of the outbreak in the Knoxville area is unknown at this time. The affected trees are in an urban area. Judging the sample, the disease has been present in the region for a number of years and is causing mortality.

Based on our experience TCD will be difficult, if not impossible, to stop. The hope is that the beetle and disease will behave differently in the eastern U.S. It takes 3-5 years to kill a large walnut tree. There are probably other outbreaks in the East that have not yet been noticed.

Dr. Alan Windham, UT Extension Plant Pathologist, urges foresters and others to be on the lookout for unusual dieback or mortality of walnuts, especially in urban areas. This is where TCD is likely to occur first because of movement of the beetle in wood (firewood, fresh lumber).

At this time the USDA has no federal quarantine on TCD, and this disease is not on any action lists. For further information, search: http://www.ppdl.purdue.edu/PPDL/pubs/walnutthousandcankersdisease.pdf

Sunday, July 25, 2010

Pennisetum 'Karley Rose'

Asian fountain grass cultivar 'Karley Rose'(Pennisetum orientale) is a four season eye-catcher. It is reliably hardy in USDA zones 5-9. It produces smoky rose colored flower spikes (plumes) in early summer, which persist thru the winter months. Its dark green foliage begins upright in form, 2 1/2 feet tall, achieving 3 feet in height in flower. By mid- summer the grass blades cascade down, true to the name “fountain grass”.

Grow ‘Karley Rose’ in full sun or partial areas with 6 hours sunlight to maintain optimum grass form and plume color. Despite proven drought tolerance, it prefers to grow in compost rich, well-drained soil. It has a wide soil pH preference from acidic to slightly alkaline (6.2 to 7.5).

This clump growing grass is quick to establish and prospers for many years. Annual maintenance is minimal. In late fall or late winter cut back the old foliage to 3-4 inches and feed with a high nitrogen lawn grade fertilizer. Fountain grass has no serious disease or insect problems and is deer resistant and salt tolerant.

The handsome foliage and attractive flower spikes of ‘Karley Rose’ provide excellent texture and seasonal color. Use as an accent specimen or group together in mass plantings.

Thursday, July 22, 2010

'Buttered Popcorn' Daylily- Performs In The Mid-South

Daylily 'Buttered Popcorn' (Hemerocallis 'Buttered Popcorn') produces buttery yellow 6" flowers from late June thru mid-July. The 32-inch tall floral scapes are well branched and flowers are mildly fragrant. Bud count on each scape may average 10 or more.

This tetraploid cultivar is also well known for its incredible fall re-bloom. In the Southern Appalachian Region (zones 6-7), 'Buttered Popcorn' is rated as a better re-blooming daylily than popular favorite 'Stella de Oro'.

Daylilies require little care. They grow in almost any well-drained soil type. Daylilies grow best in full to partially sunny areas. Allow 6 hours of sunlight for high bud bloom count. Although drought tolerant, re-blooming varieties perform best with 1-inch or more of water (or rainfall) per week during the summer months.

In late fall, cutback daylilies to 3-6 inches in height. Remove the old plant debris. Daylilies possess good disease and pest resistance. Fertilize once with 10-10-10 and mulch plants in late winter or spring. Feed a second time in early June before flowering begins.

Daylilies are great additions to large containers or plant them in garden beds. The short (under 24-inch tall) daylily varieties are also utilized as ground covers along steep slopes.

Sunday, July 18, 2010

'Diabolo' Ninebark as Small Patio Tree

photo: 'Diabolo' ninebark trained as a small tree

I saw this idea several years ago at an Ohio nursery. Common ninebark (Physocarpus opulifolius) is basically a utility shrub, inexpensive to purchase in large quantities. This midwest native grows in almost any soil or landscape environ except shade and bog areas. Over the past decade ninebark has gone to "beauty school", and a number of new cultivars, including purple leaved 'Diabolo', are currently available.

Ninebark is a vigorous grower and possesses a unique exfoliating bark trait. In the hands of a capable pruner, ninebark can be easily shaped into a small 10-12 foot single stemmed tree. The purple 'Diabolo' foliage plus its inner light tan-colored ninebark adds up to a winning landscape combination.

I suspect that suckering at the crown will likely continue, necessitating sucker removal by a hand pruner (do not use a weed wacker) every few months. 'Diabolo' ninebark purple leaf color holds the longest under full sun and bleaches out to green by mid-summer. 'Diabolo' offers pinkish white flowers from mid-May into June, followed by red fruit clusters (seed capsules) through the summer months.

Thursday, July 15, 2010

Windmill Palm

Photo by Dr. Tim McDowell, East TN State University Botanist of an 8 year old windmill palm (now deceased)
Windmill Palm (Trachycarpus fortunei) is not reliably hardy in the Southern Appalachian region (zones 6-7), even when planted in an outdoor protected area. An alternative is to grow in a container for ease of moving it indoors before the cold weather in late autumn arrives. Windmill palm is hardy to +15° F.

If planted in a protected garden spot, dig a hole wide twice as wide and no deeper than it came in the nursery pot. Palms, particularly those which you are trying out, are best planted in very late May. Frequent watering is crucial for a newly-planted palm. The well-drained porous soil should not be allow to completely dry out. Windmill palm should be fed bi-monthly during the warm months with a water-soluble fertilizer applications.

Windmill palm may eventually grow from 10 - 20 feet in height. Its medium green palmate leaves are circular, increasing in diameter to approximately 3 feet after 20-30 years. The trunk is covered with dense, light brown, hair-like fibers, easily damaged, and made vulnerable to insects and fungus.

Monday, July 12, 2010

Japanese Maple Selections for Mid-South

Photo: 'Sango Kaku' coral bark maple in November

Japanese maple (A. palmatum) offers a vast array of shrub and tree forms of varying heights and leaf shapes. Spring and summer leaves vary from gold, to dark green, to deep red and some color variegation and either cutleaf or dissected forms.

The dissected leaf forms of A. palmatum prefer morning sunlight and protection from winter wind and summer heat. Several hundred cultivars are available through local and mail order sources. Some popular cultivars grwon in the Southern Appalachian region (zones 6 & 7) are:
· ‘Tamuke yama’, ’Inaba Shidare’ (Red Select), and ‘Crimson Queen’ are weeping, red cutleaf forms
· ‘Viridis’- weeping green cutleaf to 20-25 feet
· ‘Seiryu’ - upright green cutleaf to 15 feet
· ‘Bloodgood’ - red palmate leaf to 20-25 feet
· ‘Heffner’s Red Select’ retain its red summer leaf color longer the popular ‘Bloodgood’
· ‘Butterflies’ - white variegated leaf to 12-14 feet
· ‘Sango Kaku' and 'Beni Kawa' – the "coral bark maples" with red twig and trunk bark from mid- fall thru late winter.

Thursday, July 8, 2010

Growing Hardy Banana

Hardy banana (Musa basjoo) survives winters as far north as New England and Ontario, Canada (USDA Zones 5-10). It is a herbaceous perennial which grows to 6-14' tall. Its roots, when heavily mulched, survive winter temperatures of -10 degrees F. Grow hardy banana in compost rich, well-drained soil in full sun to partial shade. Feed with a 3-6 month slow-release fertilizer supplied in early spring.

In the southern Appalachian region (USDA zones 6-7) hardy banana produces enormous 3-4 foot long leaves which gives any garden a tropical look. Give banana plants lots of space. By late summer, the large tropical leaves cast lots of cooling shade over a nearby patio or low deck . Fruit and off-white flowers are not formed because our growing period is not long enough.

If grown in containers, use a well-drained potting soil mix. Keep the container soil evenly moist, but never saturated. Reduce water and no fertilizer applications as winter approaches. In USDA Zones 5-8, store plant(s) and the container in a non-freezing area indoors over the winter months to protect the tender roots.

Plant roots become more aggressive over the years. Established plants produce numerous shoots, called “pups”. Older plants form large colonies, consuming more and more garden space each year.

Site your banana in a partially sheltered area away from high winds, which may tear the large leaves. Hardy banana has no serious insect or disease problems.

Monday, July 5, 2010

Coreopsis 'Route 66' - A Riot of Color

Create a hot splash in your garden this summer. Threadleaf coreopsis (Coreopsis verticillata) ‘Route 66’ is a new selection by Itsaul Nursery in Atlanta, Georgia (USDA zone 4 to 9). Coreopsis ‘Route 66’ originated in Pennsylvania (zone 5). Perennial gardeners have been planting yellow- flowered ‘Moonbeam’ and ‘Zagreb’ cultivars for over a quarter of a century.

The 2- inch wide yellow and red splotched flowers bloom continuously from June thru August. The center red pigment seems to bleed into the yellow petals. In the autumn the red tint becomes more dominant. No two blooms are ever alike. Deadheading will extend the blooming time span into October. Foliage is green and narrow (thread-like). Plant form is upright and well branched. Route 66 grows 2 to 2 1/2 feet in height, and a few inches wider than tall.

Plant in well-drained soil in full sunlight. Route 66 is a garden performer, a low maintenance perennial to enjoy in your garden for many years ahead. Route 66 exhibits exceptional plant vigor and flower power. One year old established plants demonstrate exceptional heat, drought and cold hardiness.

Friday, July 2, 2010

"pH Nutrient Creep? -You Nailed It"

Photo: Foliar iron deficiency on river birch
River birch (Betula nigra) is a popular landscape tree in the Southern Appalachian region (USDA zones 6-7). The cultivars 'Heritage' and 'Duraheat' have made a good native species even better with resistance to aphid and leafhopper insects. However, river birch demands a soil pH which is moderately acid. Why?

Iron is an important minor nutrient element. If the soil pH rises (becomes less acidic), available iron becomes less available to plants. Major landscape trees also affected by "pH nutrient creep" include favorites as pin oak, willow oak, sweetgum and littleleaf linden. An old timey recommendation was putting several nails in the bottom of the hole at planting time.

Modern day solutions include: 1. adding elemental sulfur in late fall to lower the pH and next year's new foliage should stay green all summer long; OR 2. apply iron supplying fertilizers like Ironite® or Sequestrene®, following package rates accurately; OR 3. feeding acid raising soluble fertilizers like Miracid™ or Hollytone® which contain iron.

Follow any one of these three approaches and summer color will gradually return this summer or next.

Monday, June 28, 2010

Culver's Root (Veronicastrum)

Photo: new cultivar ‘Fascination’ with lavender purple flowers

Midwest native Culver’s root (Veronicastrum virginicum) starts the summer flowering season in my perennial garden. It naturally grows in open woods and meadows and thrives in fertile to moist soils. However, this deep rooted plant hasn’t complain about the current dry period in the Southern Appalachian region (USDA zones 6-7).
Culver’s root can be somewhat aggressive. Over a decade in my garden, a single plant now occupies 18 square feet. It prospers in infertile clay soil. When grown in full sun, it does not require staking. I grow it in the rear of the flower bed next to another favorite - goldenrod (Solidago spp.).
The narrow floral spikes stand 3-5 feet tall, depending on the variety. White flower spikes are most common, and attract large numbers of butterflies and bees. Flowering continues over 4 to 6 weeks, the terminal blooms first and secondary laterals in late July. Floral designers love the keeping quality of the bloom spikes and lovely narrow leaves which are arranged in whorls around the branchless stems.
Culver’s root is a low maintenance perennial. It will re-bloom if old flower spikes are deadheaded. There are no disease or insect problems.

Friday, June 25, 2010

Agapanthus- Hardiness Issues

Lovely agapanthus (Lily of the Nile) is native to South Africa and is not reliably hardy in the Southern Appalachian region (zones 6 – 7). Many small tubular flowers comprise each ball -shaped (umbel) flower cluster. Tall sturdy floral scapes rise 1 to 4 feet in height, blooming from late spring into late summer depending on the cultivar. Many cultivars are available in shades of blue, purple and white.
In this region, agapanthus may be dependably grown in outdoor landscape planters which are brought inside in the fall. Agapanthus has multiple cultural issues: cold hardiness, wet wintry soils and hungry voles. Further south in zone 7-b, the crown may be covered over with several inches of leaves or mulch in late fall. The mulch is removed once the threat of spring frost has passed.
Agapanthus produces attractive glossy, strap-like green leaves, which grow from its fleshy tuberous roots. It is propagated by division of the root clumps immediately after flowering. Divide vigorous clumps every 2 to 3 years in early spring.
Agapanthus prefers a well-drained, fertile, slightly acidic soil. Locate the plant in a warm, sheltered spot under partial sun. Space plants 24 inches apart with its shallow surface roots barely visible on the ground.
Don’t permit agapanthus to dry out. Weekly watering encourages a deep extensive root system. Soggy soil is never good; the leaf tips turn yellow in a waterlogged soil.
Agapanthus requires light constant feeding in the spring and summer months using either water-soluble or slow release fertilizer with a 10-20-20 ratio. In the fall stop feeding and reduce watering to induce plant dormancy.
Pruning is done sparingly, usually to remove damaged or dead foliage before new leaves emerge in the spring.
Mealybug , red spider mite, and voles may become significant pest/critter problems.

Monday, June 21, 2010

"My Maple Tree Is Being Invaded"

photo: Dr. Alan Windham, UT Plant Pathologist

The following is a real query sent to an Extension agent over the phone: “I have thousands of insects on 8 of my 10 maple trees. I fear they will kill my trees, one has already died. The insects huddle together. I am not positive they have wings, they may, but refuse to fly. Their antenna are twice as long as their body; 6 legs; body is 1/4” long, blackish, the body tapers to a pointed rear end. I see multiple groups on my tree branches. Smaller, shorter ones have white lines across body. They are the younger ones.
Barklice also called psocids (Order Psocoptera feed on mold/fungi etc. on the bark). They are harmless and tend to aggregate. There are immatures (without wings) and adult (winged) present. The photo shows the winged barklice adults.
Lesson learned: not all insects are harmful, ready to injure your garden plants. Are you curious what killed the homeowner's other maple tree last year? I am too, but he cut it down before anyone could diagnose it.
Contact your local county Extension office for gardening assistance.

Friday, June 18, 2010

New Hardier Gardenias

Old fashioned gardenias or cape jasmines (Gardenia jasminoides) are reliably hardy in USDA zones 7-b and 8. Plants require immediate protection when the outdoor temperatures dip below 15 to 20 degrees.

The new hardier cultivars are compact growers, 2-4 feet tall and 3-4 feet wide. ‘Frost Proof’, Crown Jewel™, and Heaven Scent™ are three promising hardy cultivars to try in USDA zone 7-a. All three strut great thick, high gloss, dark green foliage.

Choose a garden location with good air circulation. Morning sunlight and afternoon shade is the rule. Plant gardenias in a well-drained acidic soil, and generously amended with compost. Water plants when dry and never overwater them. Acute leaf drop occurs in poorly drained soil. Fertilize once a year after the heaviest blooming cycle in June has past.

Fully capture gardenia's fragrance by planting in a garden spot or a container nearby a deck or patio. Individual blossoms generally last a few days. Flower loss may be rapid following a wind and rain storm.

Prune gardenias is immediately after blooming in early July. Remove all dead or unsightly shoots anytime you see them. Additional scattered blooms may occur anytime during the growing season. Late pruning should be avoided in the fall as next year's flower buds are being set.

White flies and flower thrips are major nemesis of gardenias. Bayer Advanced Tree and Shrub™ (soil drench) and horticultural oil (spray) should clean up most pest problems. Always read the pesticide label before using!

Sunday, June 13, 2010

Smaller Southern Magnolias

The grand Southern magnolia (Magnolia grandiflora) thrives here in the southern Appalachian region and along the Eastern seaboard as far north as Boston (USDA zones 6-9). Most homeowners do not have room enough to grow this 60-70 foot arboreal aristocrat.

Compact forms are available that need less than half the space. The ivory white flowers are fragrant and 25% smaller than full sized trees. Blooms open individually, not all at once, from late May thru the summer months. The most popular compact cultivar is ‘Little Gem’. It grows to a height and width of 40 x 35 feet in 25-30 years. Others include ‘Hasse’ (45 x 20 feet) and Teddy Bear® (30? x 20 feet).

The newest introduction is ‘Kay Parris’ with exquisite polished green wavy leaves and mahogany brown beneath. The parents of ‘Kay Parris’ are 'Little Gem’ and 'Bracken’s Brown Beauty’. As a young tree, 'Kay Parris' exhibits an upright, narrow (columnar) form, rating it a great evergreen tree for a small garden space.

Southern magnolia is planted from late winter through early fall in well-drained, organically amended soil in a full to partially (6 hours minimum) sunny area. Tree rarely has disease and insect issues.

Thursday, June 10, 2010

Squash Vine Borer

photo credit: Dr. Alan Windham, Univ. of TN Extension Plant Pathologist

Squash vine borer (SVB) damages squash, gourds, and pumpkins. Cucumbers and melons are usually not attacked by the SVB.

The adult SVB is a clear-winged moth. The 1 inch long adult moth is commonly mistaken for a wasp. Its abdomen is ringed with orange and black. Females lay oval brownish eggs on plants in late May or early June. The borers tunnel into stems near the soil and feed on the plant. Excrement is visible near points of entry on the stem when larvae are feeding. Heavy feeding causes the infested vine(s) to wilt and die.

Select a variety which is SVB tolerant. Also, cover emerging plants with row covers to reduce possible damage. Remove row covers when the plants begin to bloom to permit insect pollination. Stagger new plantings every 2-3 weeks to avoid SVB populations.

Some gardeners cover the main stem with pantyhose to prevent egg laying by adults. Infested stems can be split and larvae removed. Add a spade-full of moist soil over damaged stems to encourage new root growth. Insecticides must be applied prior to borers entering into the stem.

Insecticides containing carbaryl, bifenthrin, spinosad, or permethrin are effective against SVB. Apply an insecticide every 5-7 days. Please read the pesticide label before applying.

Wednesday, June 9, 2010

Vitex 'Shoal Creek'

Chastetree (Vitex agnus-castus) is an 8-10 foot deciduous shrub or 12-15 foot tall small tree (hardiness zone 6-b thru 8). Branching habit is dense and vase-shaped (upright). It blooms over most of the summer, from June thru late August. Its 12-18 inch long blue-violet flower spikes exude a slight herbal fragrance.

‘Shoal Creek’ is a leading cultivar. Cold hardiness appears better than most, although this has yet to be proven. The finger-like compound leaves are covered with pubescent hairs. Summer foliage color is grey-green, with a faint bluish cast more visible in May and June. Its disease resistant foliage and butterfly magnetism rates this vitex in a class on its own. Foliage is highly deer resistant.

Stem die-back may occur in a cold winter, but this fast grower recovers rapidly. Since flowering occurs on new growth, prune off all dead, injured and crowded branches before the start of May. Vitex prefers full sun, but will tolerate part sun. Plant in a loose, well-drained soil and keep adequately watered during the first year. Afterwards, vitex possesses very good drought tolerance.

Tuesday, June 8, 2010

Northern Catalpa

Northern catalpa or Indian cigar tree (Catalpa speciosa) has enormous presence in any landscape setting. Finding a 70 - 80 foot tree with a massive trunk and thick sinuous limbs is not uncommon from Ohio south thru Tennessee. In summer its huge heart –shaped, pale green leaves may be easily reach 8 - 12 inches long and wide. Birds often seek shelter under the foliage canopy.

Catalpa offers a spectacular flower display lasting two weeks or more in May. The tree is common along roadsides, particularly in bottomlands, often growing in poor soil. Numerous two- inch long white flowers are borne on large terminal spikes, many unfortunately hidden beneath the enormous catalpa leaves. Each flower has small gold spots within its frilly edged corolla. Narrow cylindrical cigar fruits, 8 - 15 inches in length are easily visible in the fall and winter months.

Catalpa trees are often visited by the catalpa sphinx moth whose larvae (caterpillars) are prized by fishermen for bait. Hummingbirds are a major pollinator, attracted to the floral nectar.

This fast growing tree finds only limited value in a residential neighborhood due to its coarse leaf texture. The brittleness of small limbs demands almost constant clean-up.

Sunday, June 6, 2010

Indian Pink is a Summer Sizzler

Indian pink (Spigelia marilandica) is a strikingly beautiful native wildflower here in the southern Appalachian region (USDA zone 6 -7). Beginning in late May, bright red tubular flowers flare open, crowned by five sharply pointed pale yellow reflexed lobes (see photo).

Indian pink prospers around rich moist open woodland areas. The well-drained soil should have a pH range between 6.5 to 7.0. Generously amend a partially sunny site with compost or peat to stimulate plant vigor and repeat flowering. Healthy plants grow 12-18 inches tall. Spigelia leaves attach directly to the main stem without petioles.

Indian pink is slow growing at first, taking two to three years to reach maximum floral potential. Planting five or more in a clump creates a showier display. Eventually, a healthy grouping will colonize. Bloom time is lengthened by swift removal of the old spent flowers.

Indian pink often blooms for a brief second interval in late summer when soil moisture is plentiful. Plant debris mostly disappears before winter sets in. The brightly colored flowers attract numerous pollinating insects and hummingbirds. No disease and pest problems are observed.

Sunday, May 30, 2010

Hardy Rosemary

Rosemary (Rosmarinus officinalis) ‘Arp’ is winter hardy in southern Appalachian (USDA hardiness zones 6-b and 7-a) gardens for two decades , including some very cold winters. Other rosemary cultivars which have succeeded include ‘Athens Blue Spires’, ‘Hardy Hill’, and ‘Salem’.

Locate a site with a “micro-climate" advantage such as next to a driveway or along the southside of a red brick home or a dark colored garage wall. Here winter temperatures vary by a few degrees warmer. Dark asphalt pavement absorbs and retains heat. Next to large bodies of water, such as a swimming pool and a water garden, may also be slightly warmer in the winter.

Plant rosemary in well-drained soil and in full direct sunlight. With rosemary and other semi-tender herbs, winter kill may also be caused by wet, soggy soil rather than cold.

‘Arp’ matures a handsome woody shrub with fine textured foliage. It grows 3-4 feet tall and wide, and blooms in early spring. The blue flowers are small and attract lots of insect activity.

Monday, May 24, 2010

Dreaded Rose Rosette Disease

No rose is resistant to this deadly virus disease. Symptoms of rose rosette disease (photo) vary greatly from the species or cultivar planted. Leaves may be small, distorted, and exhibit a conspicuous red pigmentation. Diseased canes may also be noticeably thicker than others around them, and/or may grow in a spiral pattern.

Multi-flora roses, a noxious shrubby weed, are most susceptible and often are first to contract the disease. Very small eriophyid mites transmit rose rosette disease by feeding off the plants which are already infected. Mites transmit the virus to healthy roses nearby. Control measures must be rapid and decisive.

Insect spraying will help. Spray roses with Sevin (carbaryl) insecticide for partial control of the eriophyid mite. Eliminate multi-floral roses within 300 feet from any rose plantings, preferably from all surrounding yards and gardens.

Prune out all diseased and suspected canes. Remove all prunings immediately from the property. If symptoms reappear on new re-growth canes, remove the bush from the property. When planting roses, space them far enough apart that foliage does not touch neighboring plants.

Saturday, May 22, 2010

Lovely Lavender

photo: 'Munstead' lavender

Lavender is a hardy shrub that thrives in dry alkaline soil. Lavender is commonly used as a food seasoning, a culinary substitute for rosemary. Dried flowers are crafted into table arrangements and lavender fragrance is captured in sachets and potpourris. Lavender is used to store clothes as a moth repellent. Some people store some under a pillow as a sleep aid, a form of “aromatherapy”. Bees produce a high-quality honey from the flower nectar.

There are two kinds of lavender. The shorter-growing cultivars of English lavender (Lavandula angustifolia) like ‘Munstead’, ‘Hidcote’, and ‘Lady Lavender’, flower in mid-May for one month. When cutback, English lavender blooms again in August. The taller more vigorous French lavender (recommend cultivars ‘Provenance’, ‘Grosso’ and ‘Super’) flowers only once in late June. For lavender oil production, I recommend ‘Super’.
Lavender is only successful planted in soil that is exceptionally well drained. An ideal soil pH range is 6.5 - 7.2. Grow on raised mounds and space plants 3 feet apart in the row and 6-8 feet in the row, if grown commercially. Other than for harvesting, prune plants back one-third in a ball shape in September. Lavender has very few disease and pests problems and possesses high drought tolerance.

Thursday, May 20, 2010

FireBlight on Apples and Pears

Fireblight is a serious bacterial disease that afflicts apple and pear trees. Fireblight may appear in two distinct forms. From April to early May flowers and fruit clusters may blacken (die). From May to mid-June a more serious symptom (photo) is sudden dieback, almost overnight, of branch tips . Leaves appear as if someone had poured gasoline over the tree and torched it. Infected branch tips may also look curled, as a so-called "shepherd's crook".

To prevent the spread of fireblight, prune off all diseased wood, cutting back 6 - 8 inches into adjacent healthy shoots. Pruning is done either when first seen or when the tree is dormant. Disinfect the pruning shears after each cut, dipping the blades into either rubbing alcohol or 20% bleach to water solution. Remove all diseased prunings from the property. Do not compost.
When planning an apple or pear home orchard, avoid planting very susceptible varieties such as 'Lodi', ‘Gala’, ‘Jonathan’, ‘Rome’, and ‘ Yellow Transparent'. Among pear varieties, ‘Bartlett’, D’Anjou’, ‘Bosc’ and ‘Clapps Favorite’ are most susceptible, and ‘Moonglow’, ‘Maxine’, ‘Magness’, and ‘Seckel’ are moderately resistant to fireblight. Most Asian pear varieties are very susceptible.

Monday, May 17, 2010

No-Spray Shrub Roses


Photo: Carefree Sunshine Rose at UT Gardens in Knoxville, TN
Over the past decade the Knockout®, Carefree® and Home Run® series of shrub roses have altered the appearance of residential and commercial properties. From 2006 -08, no-spray rose trial was conducted at two University of Tennessee Research and Education Centers in Jackson and Crossville, TN and the USDA Horticultural Research Lab in Poplar, MS.
Over 135 cultivars were evaluated. "The ultimate disease test for roses is to test them south of the Mason-Dixon line where disease pressure is highest", according to Dr. Mark Windham, UT Research Pathologist.

Shrub Roses Resistant (R) or Moderately Resistant (MR) to Black Spot and Cercospora Leaf Spot:
Carefree Sunshine (MR) - F
‘Fiesta’ (MR)
‘Golden Eye’ (R]
‘Hansa’ (R) - F
‘Homerun’ (MR)
Knockout Rose (R)
‘My Girl’ (R) - F
‘My Hero’ (MR)
‘Palmengarten Frankfurt’ (MR) - F
Pink Knockout (R)
‘Super Hero’ (MR)
’Wild Spice’ (MR) - F
‘Wild Thing’ (MR)
‘Wildberry Breeze’ (R) - F
F indicates rose is fragrant

Saturday, May 15, 2010

Best of the Climbing Roses So Far-- 'White Dawn'


Since its introduction in the rose world over 60 years ago, 'White Dawn' has proven to be a top garden performer among climbing roses. The dark green, glossy foliage is very blackspot disease resistant. This very vigorous climber (hardiness zone 5 – 9) grows to 12 to 20 feet. Pure white double flowers are medium-sized (2-1/2" to 3"). 'White Dawn' tolerates poor soils if drainage is good. It blooms best in a bright sunny spot.

'White Dawn begins blooming in mid-May in the southern Appalachian region (Zone 6-b to 7-a) and repeats, off and on, through the rest of the growing year. Feed roses starting in early April and monthly to early September with Miracle-Gro®, Schultz®, or equivalent water soluble rose food @ 1 tablespoon per gallon.

Prune climbing roses in late winter (March) when new growth begins. On young climbers, simply remove all diseased, dead and tall nuisance canes. On older climbers, cutback the oldest rambling canes, favoring strong healthy one-year shoots which produce most of the rose blooms in May.

‘White Dawn’ is the first climbing rose to earn the University of Tennessee “No Spray” designation.

Friday, May 14, 2010

Yellowwood --"In The On-Year"


American yellowwood (Cladrastis kentukea) is a medium-sized flowering landscape tree. Generally, from early to late May, the beautiful yellowwood tree blooms in the Southern Appalachian region (USDA zone 6-b to 7-a). Twelve to fourteen inch long white pea-shaped flower panicles drape from the tips of tree branches.

I know the location of a dozen yellowwood trees in northeastern TN and 11 of 12 did not bloom in 2009. The 12th tree bloomed sparsely. In 2010 all trees are exceptionally beautiful in full bloom this week and last. So far, plant scientists are at a loss predicting the “on” and “off” annual flowering pattern.

Yellowwood may bloom 2 to 3 consecutive years and not flower again for the 1-2 years. A complex of environmental and physiological factors may be involved. The weather history over the past decade in the Southern Appalachian region has included several abnormally hot, dry summers and mild winter temps. The 2009 summer was unusually cool and moist followed by a longer cold winter.

A second theory, called "biennial bearing", states that if a tree sets an unusually heavy seed load in the summer, few to no flowers are initiated for the following spring.

The flowering trigger for yellowwood tree is not understood. Whether in flower or not, yellowwood makes a fine addition to any landscape.