What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

‘Notify Grounds Crew’ Daylily

Posted by Hugh on August 5th, 2010

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.

Arkansas Amsonia – 2011 Perennial Plant of the Year

Posted by Hugh on August 2nd, 2010

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.

Plumleaf Azalea Is Showy Summer Blooming Shrub

Posted by Hugh on August 1st, 2010

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 has rarely been done on my 15+ year old plant purchased at Callaway Gardens. Plumleaf azalea grows 8-10 feet tall. I maintain it at 6 by 6 feet tall and wide for a short and wider spreading shrub. An errant branch is occasionally clipped back into the fold.

Thousand Cankers Disease Found in Knoxville, TN

Posted by Hugh on July 29th, 2010

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

Pennisetum ‘Karley Rose’

Posted by Hugh on July 25th, 2010

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.

‘Buttered Popcorn’ Daylily- Performs In The Mid-South

Posted by Hugh on July 22nd, 2010

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 on steep slopes.

‘Diabolo’ Ninebark as Small Patio Tree

Posted by Hugh on July 18th, 2010

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.

Windmill Palm

Posted by Hugh on July 15th, 2010

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.

Japanese Maple Selections for Mid-South

Posted by Hugh on July 12th, 2010

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.

Growing Hardy Banana

Posted by Hugh on July 8th, 2010

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.