Sunday, March 28, 2010

Golden Hakonegrass Lights Up The Shade Garden

Light up dark areas in your shade garden with this wonderful golden ornamental grass from Japan. Golden hakonegrass (Hakonechloa macra 'Aureola') grows 12-18 inches tall and 18-24 inches wide with a mounding cascading form.
Very thin green stripes (veins) flow the length of the ½ inch wide golden leaf blade. The cool nights in the fall adds a pink to reddish tinge to the blades before all dies back for a long winter’s nap. Tiny, relatively inconspicuous, floral spikes appear for a short time in late summer.
Golden hakone prospers in moist humus-rich, well-drained soil. Contrarily, it grows poorly in compact heavy clay soils. Hakone prefers a partially shaded garden spot, receiving 2 hours of early morning or 1/2 day of dappled sunlight.
Golden hakone grows slowly, spreading by stolons and rarely trespasses spaces occupied by neighboring hosta, astilbe, heuchera and other companions in the shade garden.
Golden hakone is rarely bothered by disease or insect pests and is not troubled by deer. 'Aureola' hakone grass was selected the Perennial Plant of the Year in 2009.

Saturday, March 27, 2010

Viburnums for Privacy Screening

photo: the clean summer foliage of 'Allegheny' viburnum
Must you plant an evergreen hedge when a semi-evergreen flowering shrub is fine for the task?
Leatherleaf viburnum hybrid cultivars 'Allegheny' and 'Willowwood' are 60% evergreen, dropping their foliage very late in autumn in U.S.D.A. zones 6 and 7-a. 'Willowwood is preferred over 'Allegheny' in areas of zone 6 and 7 where powdery mildew disease may be a problem.

Prague viburnum (Viburnum pragense) is the only "true" evergreen viburnum. It possesses lustrous dark green foliage year-round and grows to 9-10 feet. Its height is tall enough to become a beautiful privacy screen and noise barrier from the neighbors and traffic.

All three viburnums are excellent growers. They have a distinct advantage over most conifer species used in privacy screening. These lovely viburnums flower in late spring and early summer, something the conifers don't offer.

Friday, March 26, 2010

When to Prune Flowering Shrubs

photo: Weigela 'Wine and Roses'

Prune spring flowering shrubs and trees immediately within one month after flowering. These plants set their flower buds on last summer's woody shoots. Common shrub examples include forsythia, lilac, weigela, mockorange, loropetalum, honeysuckle, and many viburnum species.
Summer-flowering plants set their flower buds on spring wood (this year) when they bloom. They are pruned in late summer into early fall (after flowering). You may also wait until late winter into early spring before shrubs leaf out. Some examples are crape myrtles, althea (Rose of Sharon), chaste tree (vitex) and most hydrangeas.
Other tips: remove all dead, diseased, and damaged wood anytime of year. If scale insects are present, remove the worst infested shoots, reducing the need for pesticide spraying.
Prune off weak spindly wood if it takes away from the desired shape or form of the shrub.
Finally, you can reduce shrub height by pruning off the branch(es) at point of origin, near the ground around the base of the shrub.

Sunday, March 21, 2010

Lo and Behold 'Blue Chip' Buddleia is a Winner

photo taken at JC Raulston Arboretum in June 2009
Lo & Behold® ‘Blue Chip’ is a very dwarf butterfly bush (buddleia) for the summer garden. Take advantage of its compact 3 x 4 foot height and width by planting it in the garden or in a container on a sunny patio deck or patio by itself . In large containers mix in shorter growing summer annuals such as trailing petunia, scaevola or alternanthera.

Lo & Behold® ‘Blue Chip’ maintains its clean growing habit all season long. Gardeners with limited space can attract butterflies and hummingbirds to their garden with this colorful buddleia. It produces loads of fragrant blue flowers which bloom continuously. It thrives in the summer heat and humidity and the foliage stays blemish-free.

'Blue Chip' is non-invasive. It's self-cleaning and will bloom from mid-summer to frost without deadheading. Each proceeding spring, you won’t need to drastically prune 'Blue Chip' as you would the larger growing buddleia varieties. Plants are deer resistant and drought tolerant.
‘Blue Chip’ was still blooming in my Southern Appalachian garden in late October .

Wednesday, March 17, 2010

Best of Perennial Veronicas for Gardens

photo: Veronica spicata 'Royal Candles' (not evaluated in CBG study)

Chicago Botanic Garden (CBG) has published the results of a 10-year study of speedwells (Veronica and Veronicastrum) in its 33rd issue of Plant Evaluation Notes, “A Comparative Study of Veronica and Veronicastrum".

Seven speedwells received good-excellent ratings for their overall performance, including Veronica ‘Fairytale’, V. ‘Giles Van Hees’, V. austriaca ‘Ionian Skies’, V. longifolia ‘Blue John’, V. spicata ‘Baby Doll’, V. spicata ‘Ulster Blue Dwarf’, and V. wormskjoldii. These top-rated speedwells exhibited strong growing and excellent flower production throughout the evaluation period. The lack of any serious pest or disease problems, along with good winter survivability, contributed to their high ratings. Additionally, 18 taxa received four-star good ratings for similarly strong performances.

Speedwells are generally easy to grow and prefer sunny locations in moist, well-drained soils. Plants grown in less light will not bloom as profusely and may become lax or open in habit. Crown loss or plant death may occur in wet soil conditions in winter.

Many speedwells require a midsummer shearing after the first bloom to promote a healthy new basal foliage and to encourage late summer flowering. Deadheading of spent blooms produces many new bloom spikes later in the summer. By selecting the best cultivar(s), you may avoid potential foliar diseases, including powdery mildew, downy mildew, leaf spots, and foliar rust.

Generally, plant disease pressure is more severe here in the Southern Appalachian Region than in the Midwest. Read the entire 8 page CBG report (Issue 33, 2010) authored by Richard G. Hawke.

Monday, March 15, 2010

Growing Spuria Iris Worth The Challenge

photos courtesy of Iris City Gardens

Jimmy Turner, Dallas Arboretum horticultural guru, gave me this idea. Growing spuria iris in the Southern Appalachian region can be quite challenging. Hardy to USDA zone 5, spurias are dormant (asleep) during our usually hot, dry summers. A wet summer is a real “downer” for spurias.
Spuria irises bloom two weeks after the popular tall beard iris. They grow and flower best under full sun. Spurias are not choosy about soil type and pH. Bloom stalks can reach 4+ feet in height in a good garden soil.
Foliage dries up in the heat of summer, very natural for spuria iris. Gardeners should not attempt to revive them with irrigation. Autumn showers revive plants. Once growth re-starts, plants hate to dry out.
Spurias need one year to become established. Space plants at least 3 feet apart. Divide them every 5 years. Natural rainfall in our region is usually plentiful. The easiest way to kill spurias is to mulch and overwater them.
You may purchase spurias from several mail order nurseries or local nurseries which specialize in iris. Personal shopping emporiums include Iris City Gardens in Nashville, TN and Heritage Gardens in Greeneville, TN.

Sunday, March 14, 2010

Time to Plant Early Vegetables

Photo credited to University of Illinois Extension

Spring weather seems to have finally arrived here in the Southern Appalachian region. While the weather has changed for the better. Night time temps have remained above 30° F over the past 8-9 days. Spring frosts in the morning are common in this region into early May. More snow showers will likely occur, so it is wise not to stow away the snow shovel just yet.

St. Patrick's Day (March 17) signals the traditional start for planting early veggies, called the cole crops, within USDA zones 6-b to 7a. Night temps in the mid-20's are unlikely to injure these cool season vegetables.

Why the early start? Well-rooted young plants in March better cope with the warm 70°F days ahead in April and May. Poorly established vegetables like cabbage, broccoli and cauliflower get "heat stroke" on hot days and likely will bolt (go to seed).

Plant your greens - lettuce, mustard, spinach, chard and kale. Turnips provide both greens and edible roots. Root vegetables such as carrots, potatoes and radishes are part of the early spring agenda.

For carrots to develop well, they require a loose, friable soil. Most of us garden in a tight, clay soil. I advise planting carrots in a raised bed, mixing generous amounts of compost into your soil, creating a porous and deep-rooting grow medium.

Wednesday, March 10, 2010

Re-blooming Amaryllis -- Just Add Water

An amaryllis bulb is nature’s equivalent of a re-chargeable battery. In the fall stop watering to push the bulb into dormancy (sleep). Most leaves wither and die within 4-6 weeks. Remove a dried leaves (for neatness). The bulb must remain dormant for a minimum of 8 weeks. Store the pot anywhere, in a closet shelf or out in the garage, provided the storage temperature does not drop below freezing (32° F).
Every few weeks, restart a potted amaryllis bulb. Place in an east or south-facing window of your home, and add water. Pre-mix a water-soluble fertilizer in the water according to manufacturer’s directions. First watering requires that you sink the pot bottom in a pail of water/fertilizer for 2-3 hours to fully adsorb water and nutrients. Turn the pot weekly so the plant and flower stalk grows straight up.
Your amaryllis will bloom in 4-6 weeks. Enjoy it! After flowering, continue to water and feed the plant until it can be moved outside onto a sunny deck or patio in mid to late spring after the frost danger has past. Your amaryllis will flourish through the summer months and will be fully recharge by autumn.
Repot your amaryllis every 3-4 years in the fall after dry-down. Divide and give away the extra bulbs to garden friends to enjoy. I enjoy shopping for new amaryllis bulbs at local garden shops and on-line at

Monday, March 8, 2010

“Pruning Cuts –Avoiding the Big Ones”

Question: was this pruning cut a mistake? You judge.
Driving home yesterday, I spied upon this extreme pruning cut (see photo). The tree pruner may have read the chapter in the pruning manual about cutting a damaged or broken limb on an angle to shed snow and rain. Had he/she missed the chapter that recommends making the smallest possible cut? This cut is very large.

Whenever possible, make small cuts and on a 30°- 45° angle. I have the advantage of seeing the oak tree up close. In this case, tree pruner may have experienced extenuating circumstances. I had not seen the extent of injury to this storm damaged tree. I've concluded that this tree cut is correct.

Each pruning cut is a wound. A small cut heals more rapidly than a wide cut. Cutting on an angle is correct, creating the smallest possible diameter wound. There is no need to apply a tree wound paint or sealant. These products are simply cosmetic.

Prune most trees and shrubs in late winter unless they flower in spring. If you delay, spring-flowering plants may be pruned within one month after blooming. Prune summer-flowering shrubs and trees in late February and March because their flowers are initiated on new spring -summer growth.

Saturday, March 6, 2010

Aucuba -- the "Holly" of the Shade Garden

On a recent trip to the Knoxville Botanical Garden, I was re-introduced to a shrub, not used as much as it should be - gold dust plant (Aucuba japonica). Hardy to garden zones 6b-10, aucuba is at home in part sun to heavily shaded areas in the garden. Direct sunlight, even in the darker winter season, will scorch the foliage.
I've enjoyed a "plain green" foliage variety in my landscape over the past 16 years. It is tucked among three Japanese maples. Its holly-like leaves and bright red berries (on female cultivars)become more noticeable after the surrounding maples have surrender their fall plumage.
Many gold leaf cultivars sparkle in an otherwise dreary winter garden. Many cultivars abound. I particularly like 'Picturata', exhibiting large bright golden splotches in the center of each leaf and splashed by tinier yellow specks.
Branches on this 8-10 foot tall shrub are upright in habit. Growing culture is the same as hollies - preferring a well-drained, richly composted and moist soil site.

Monday, March 1, 2010

Japanese Apricot Blooms in Winter

Japanese apricot (Prunus mume) is a beautiful reminder that the worst of winter may be behind us. On days barely above freezing, the light pink fragrant blossoms open, rarely in great numbers. Cold nights freeze the blossoms but other buds will open during the next warmup.

Japanese apricot is cold hardy in garden zones 5 thru 7. It is a small 10-12 foot tree, rarely bearing fruit. Plant in a full sun area of the garden, near decks and patios where you can visually enjoy the winter bloom from inside your warm home. The tree is likely to coax you outside.

Japanese apricot does not prosper in hot or dry locations. Plant in a moist, well-drained soil, mulch when needed, and prune to maintain an open branched tree. Over a dozen cultivars are available in white, pink, or red tones and single, semi-double or double blossoms.