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.