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.

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.

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.

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.

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

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.

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.

Growing Tomatoes in Containers

Tomato Fest V in August 2009 in Kingsport, TN

Apartment renters and townhouse and condominium owners till the soil in containers on their patio and deck. For containers the shorter growing determinate type tomatoes are a better choice. Spread out the harvest interval, by not planting all your tomatoes at one time. Start your last tomatoes from seed for June planting and harvest beginning in late September and October.

Container grown tomatoes need a deep container- at least 16 to 18 inches tall. A 5- gallon (or larger) pail or pot works well. Drill out several 1- inch wide drainage holes and add a few rocks in the bottom for ballast. Plant in a good growing media and add some inorganic fertilizer or organic bone and blood meal to increase fertility. Container-grown plants require more frequent fertilization than field-grown, as there’s less soil from which to obtain nutrients. For water soluble fertilizers, apply every two weeks.

Here are some good varieties to try. The yield will vary with the variety:
• Slicers
– Bush Early Girl
– Bushsteak Hybrid
– Spring Giant
– Better Boy
– Jetstar
– Bush Celebrity
– Mountain Fresh Plus VFFN
– Super Bush
– Saladette (Roma type)

• Cherry
– Golden Nugget
– Sweet 100 Patio
– Tiny Tim
– Patio
– Supersweet 100
– Sun Gold

Alternatives to Italian Cypress

'Sky Pencil' Holly at Chanticleer Gardens in Wayne, PA

Those of us who live north of Atlanta, GA (USDA zone 7-b) can not enjoy Italian cypress (Cupressus sempervirens), which are not hardy in most of the Southern Appalachian region (zone 6-a to 7-a). If you are designing a Mediterranean look in your garden, choose among select cultivars of these columnar evergreen shrubs:
Japanese holly (Ilex crenata) 'Sky Pencil'
Upright boxwood (Buxus sempervirens) 'Dee Runk' and 'Pyramidalis'
Red cedar (Juniperus virginiana) 'Taylor', 'Brodie', 'Blue Arrow', 'Idyllwild'

Eastern arborvitae (Thuja occidentalis) 'Techny', 'Pyramidalis'

Common juniper (Juniperus communis) 'Pencil Point'
Alaskan cedar (Chamaecyparis nootkatensis) 'Green Arrow', 'Van den Akker'

Hinoki cypress (Chamaecyparis obtusa 'Vokel's Upright')

Arizona cypress (Cupressus glabra) 'Limelight', 'Silver Smoke'

Rocky Mountain juniper (Juniperus scopulorum) 'Skyrocket', 'Moonglow' -- needle foliage breaks down over time in warm 6-b to 7-a summers. Better in zone 6-a and further north.

‘Upright Japanese barberry (Berberis thunbergi) 'Helmond Pillar' – deciduous

Likely, you may be challenged by a lack of availability of several of these fabulous conifers at local garden centers. Often, an internet source becomes your best option for purchasing one or more.

Growing Blueberries

Both the highbush and rabbiteye blueberry (Vaccinium spp.) are hardy in the Southern Appalachian region (zone 6-b to 7-a). A hot summer is a nemesis for highbush and an extremely cold winter limits where you can grow rabbiteye within zone 6-b.

Blueberry bushes grow 8-15-feet tall, requiring annual pruning. Its dark green foliage turns brilliant red in the fall. Pale pink flowers appear in the spring followed by the berries which start out as pale-green (pictured) and ripen to dark bluish-purple.

Blueberries are very shallow rooted and must be irrigated regularly during their growing season.

Space blueberry bushes 5 to 7-feet apart with rows 8-feet apart. Mulch with a black fabric matted base and cover with an additional 3-4 inches of sawdust, wood chips or pine needles. For info. on garden soil prep, see blog dated 4/30/10.

Use an organically-based, slow release fertilizer composed of sulfur-coated prills. A newly blueberry plant starts with one ounce of ammonium sulfate to a maximum of 8 ounces of ammonium sulfate for a mature bush per year. Bushes reach full production in 6-10 years.

For highbush blueberries (I recommend 'Duke', 'Bluecrop' and 'Blueray' cultivars) are harvested starting from mid- June thru late July and rabbiteye ('Tifblue' and 'Premier') are ready from mid- July thru September.

Birds love ripe blueberries as much as people do. Cover your bushes with netting or plan on sleeping outside when harvest time.

Hybrid Decidous Azaleas Brighten The May Garden

The bright reds, oranges and yellows of the hybrid deciduous azaleas (Rhododendron spp.) are lovely among tall shade trees which protect them from the harsh afternoon sunlight of summer. Because their bloodline is from our native piedmont azalea species in the Eastern U.S., hybrid deciduous cultivars possess exceptional disease and insect resistance rarely seen in the more popular evergreen forms.
This past weekend I saw this lemon yellow gem (pictured) in a friend's garden in Lenoir, NC called 'Sunny Side Up'. The very popular 'Gibraltar' (bright orange) has been blooming over the past 15 years blooming in my northeast TN garden next to 'Gold Finch' (yellow-gold).
Annual care is very minimal: Feed once after flowering with any slow release azalea or evergreen fertilizer. To invigorate the azalea, prune back one or two very tall woody branches near the base of the shrub to promote new shoot growth. The new branches will likely flower next spring and many more thereafter. One year established shrubs are also very drought tolerant.