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

Sacred Lily (Rohdea) Brings Good Fortune

Posted by Hugh on October 19th, 2011

Sacred Lily (Rohdea japonica)

Depending on where you garden, Sacred Lily (Rohdea japonica) is either an evergreen or herbaceous perennial groundcover. It is slow growing and prospers in a moist shady woodland environment. Small clumps of long, strap-like leaves emerge from an underground crown to about 15” in height. Foliage is comprised of 18 inch long strap- like leaves which are 3 inches wide.

Sacred lily is planted in multiples as a woodland groundcover or grown by itself as a single specimen. In spring, its greenish white bloom spike is quite insignificant as it does not extend beyond the foliage canopy. In most years sacred lily produces a cluster of bright red-orange berries in the fall and winter. The fruit contrast beautifully with its dark green foliage.

It’s evergreen through zone 6 and survives further north, where the foliage dies back each winter. Sacred lily prefers a compost rich, moist well-drained soil, but does tolerate heavy clay soil. An established clump is quite drought tolerant and may be divided in early spring. Disease and pest problems are not an issue.

Native to China and Japan, sacred lily is associated with long life and good fortune. It is a treasured gift to one who receives one. There are several variants closely held by dedicated plant collectors which can be quite costly. Availability is limited to specialty plant internet sources.

Sacred lily recently has been re-classified into the lily-of-the-valley family (Convallariaceae).

Winter Storage of Non-Hardy Tropicals*

Posted by Hugh on October 16th, 2011

Musa 'Siam Ruby' at Kingwood Center, Mansfield, Ohio

There is frost on your pumpkin. By late October, northern U.S. gardeners (USDA zones 3 thru 6) must protect non-hardy tropicals such as cannas (Canna spp.), bananas (Musa spp. and Ensete spp.), elephant ears (Colocasia spp. and Alocasia spp.) and angel trumpets (Brugmansia spp.). Most gardeners living in zone 7-b and further south have little difficulty overwintering most cold sensitive tropicals outdoors.

Cannas (rhizomes) and elephant ears (tuberous roots) should be lifted from garden beds and stored in dry peat moss above freezing over winter. Container plants require winter storage as well. Stems should be cut back to the soil line and soil is shaken away from the root mass. Rhizomes and tuberous roots are stored in dry soil or sphagnum peat moss between 35-45° F.

For angel trumpets and non-hardy bananas, gardeners have two options. Option one is to cutback and bareroot angel trumpets and Musa spp. bananas. Do not cutback single-trunk bananas (Ensete spp.) as you must leave the growing point intact. To induce dormancy, store them in a cool location such as in an unheated garage or cellar (35° F minimum for cannas and 45° F for bananas). Reduce watering to once monthly and stop fertilizing, causing leaves to drop.

Option two for angel trumpets and bananas is to grow them. Angel trumpets and Musa spp. bananas are cutback to 5-6 inch stubs (for space saving) and cared for in a sunroom or greenhouse. Feed them with half-strength house plant brand fertilizer (such as Schultz™, Miracle Gro™ or Hyponex™) at every third watering.

‘Duet’ – A New Variegated Beautyberry That Is Stable

Posted by Hugh on October 13th, 2011

'Duet' Callicarpa dichotima

Variegated leaf and white fruit

‘Duet’ is a variegated leaf cultivar of white fruited Japanese beautyberry (Callicarpa dichotoma ‘Albifructus’). It was discovered at Tennessee Technological University in 2000 by Dr. Gary Bachman and Mr. W. Edgar Davis. ‘Duet’ beautyberry was released jointly by the U.S. National Arboretum and Tennessee Technological University.

Leaf variegation is very stable, occasionally throwing a green shoot (which should be pruned off). Growth rate is vigorous, forming a rounded shrub 6 feet tall and 6.5 feet wide in 4 years. The 3 inch long variegated leaves are medium green with a distinctive pale yellow margin.

Flowers are inconspicuous, mostly hidden by the dense foliage in mid-summer. ‘Duet’ flowers and bears fruits on new wood at a young age. Small 0.1 inch diameter white fruit (not the typical lilac-violet fruit of most beautyberries) size up in September and persist for 1 to 2 weeks after leaf drop. Several species of birds are attracted to the fruits in late autumn.

‘Duet’ grows well in an average well- drained soil with moderate fertility. Unlike many beautyberry cultivars, Duet grows in full sun in zone 7 and cooler climates, but does benefit from light shade in warmer climates. It grows well in the Southern Appalachian region (USDA zones zone 6 and 7), but survives in zone 5 if protected. Prune back and re-grow when winter injury has been severe.

‘Duet’ works well as a single specimen plant, or mass planted as a deciduous hedge or background screen in the shrub border.

Virginia Creeper – A Question of Place

Posted by Hugh on October 10th, 2011

Virginia Creeper Along Interstate 26 in TN

Autumn foliage color is upon us in the Southern Appalachian region (USDA zones 6 and 7). On a weekend drive through the Smoky Mountains, vivid red Virginia creeper (Parthenocissus quinquefolia) foliage draped highway fences and tree branches. Virginia creeper foliage peaks 2 to 3 weeks ahead of most woodland trees and shrubs.

Lots of gardeners try to rid themselves of this aggressive vine. Yes, it’s native and frequently is misidentified as poison ivy (Toxicodendron radicans). The ¼ inch diameter bluish-black fruits are numerous and birds devour them and excrete seeds over your garden and mine.

If you need a quick cover of an ugly wall, trellis or rock pile, tendrils will “cement” themselves to almost any surface. Virginia creeper grows in any kind of soil. Seedlings grow through cracks in concrete sidewalks. The foliage of this salt tolerant vine can stabilize a sand dune on beach property. Cuttings root easily, so there is little cost to establish it.

Leaves are palmately compound, commonly 5 leaflets grouped together. Often, seed leaves start out as one, later three (mimicking poison ivy), and usually five leaflets. Its greenish white flowers are mostly inconspicuous, hidden beneath the dense glossy dark green foliage in June and July.

Overall, Virginia creeper may not be a vine to invite onto your property. Potentially, it may take over your landscape, perhaps the entire subdivision. Currently, it is a beautiful to behold in early autumn landscape.

‘Diabolo’ Ninebark Has More Than 9 Lives

Posted by Hugh on October 7th, 2011

'Diabolo' ninebark tree form

The cultivar Diabolo ninebark (Physocarpus opulifolius ‘Diabolo’) is an aggressive grower. A knowledgeable gardener with a sharp pair of pruners may quickly and easily train Diabolo ninebark into a small tree. Plant a ninebark tree in a large container for multi-seasonal color around your deck or patio.

Its common plant name “ninebark” says a lot. The outer bark peels off, exposing a lovely dark cinnamon inner bark. Narrow gray-brown outer strips peel off as thin opaque tissue, many more than nine times.

In tree form, Diabolo grows more than 12 feet in height and 8-10 feet in width. When left unpruned, vigorous Diabolo can overwhelm its landscape space. Ninebark grows in any type of soil including marginal clay. To maintain a single or multi- stem tree shape demands bi-monthly pruning attention during the growing season to remove unwanted stem and root suckers. Tidy-up pruning takes less than 5 minutes.

Plant a ninebark tree in a large 25-30 gallon container or in the ground where you may enjoy its year-round beauty. Its root system is winter hardy in the Southern Appalachian region (USDA zones 6 and 7). Numerous ¼-inch wide white flowers appear in May which contrast beautifully against the reddish burgundy Diabolo foliage. By early August, the burgundy tinted leaves have faded to medium green. Autumn foliage finishes greenish yellow before dropping.

I recommend using the following hand pruners: Corona™ #3160 or Fiskars® Powergear Bypass Pruner.

Fall Color in U.S. Native Azaleas

Posted by Hugh on October 4th, 2011

R. vaseyi fall color

Finally, Americans are paying closer attention to our wonderful native plants. In the Southern Appalachian region, there are 16 and more species of deciduous azaleas which may be grown here. In addition, there are numerous natural hybrids growing in the mountains.

I asked Jay Jackson, owner of Appalchian Native Plants, Inc. in Laurel Bloomery, TN which deciduous azaleas offer the best fall color. He rated these six as the best:

Pinkshell azalea (R. vaseyi)
Sweet or smooth azalea (R.arborescens)
Swamp azalea (R.viscosum)
Natural hybrids of (R. arborescens) x (R. cumberlandense)
Cumberland or bakeri (R. cumberlandense)
Flame azalea (R. calendulaceum)

The species rating order may change from year to year with the weather conditions prior to fall foliage color-up.

Plant Autumn Asters Instead Of Mums

Posted by Hugh on October 2nd, 2011

Aster 'October Skies' (photo courtesy of NorthCreek Nurseries, Landenburg, PA)

Aromatic asters (Aster oblongifolius) is one of our finest late blooming native asters for the autumn garden in the Southern Appalachian region (USDA zones 6 and 7). Through the spring and summer months, the dense gray-green shrubby foliage mounds grow 15-18 inches high and 24-30 inches wide. Hundreds of yellow-centered, daisy type flowers cover the plants. Blooms average 1 1/4 inches in diameter. The foliage emits a minty fragrance when crushed.

The botanical nomenclature of aromatic asters was recently changed to Symphyotrichum oblongifolium. The two most popular cultivars are ‘October Skies’ with bluish ray flowers and ‘Raydon’s Favorite’, a sister seedling, with blue-lavender ray flowers. Both cultivars work well as part of a border or meadow planting, or in containers. Like most asters, flowers attract numerous butterflies and are excellent cut for a table arrangement.

Aromatic asters grow in an average soil and in full sun. In gardens asters benefit from additions of compost and fertilizer to the garden soil. Established asters are very drought tolerant. Immediately after flowering, deadhead plants to reduce seed formation which may lead wild seedlings germinating in your garden in subsequent years. Using a sharp knife, split apart and tranplant emerging mounds of young shoots in early spring.

Aster yellows is a virus disease and their mortal “Achilees’ heel”. The yellow virus is spread by sap feeding insects such as leafhoppers and aphids in spring and early summer. Prevention is your only option, using contact-type insecticides. Aromatic asters demonstrate better than average deer resistance if populations are not exceptionally high.

‘Little Lemon’ Goldenrod Acts Like Late Summer Bedding Plant

Posted by Hugh on September 29th, 2011

'Little Lemon' goldenrod (photo courtesy of North Creek Nurseries, Landenburg, PA)

Across the Southern Appalachian region (USDA zones 6 and 7), the native goldenrods (Solidago spp.) are easy to spot, growing 6-8 feet tall in ditch banks along roadsides and in the poorest of soils. Over the past quarter century short, more compact cultivars have arrived local garden centers.

‘Little Lemon’ grows only 12-15 inches tall with a 18-24 inch spread. This diminutive beauty is exceptionally compact with joyous light yellow flowers opening in late summer and blooming well into the fall season. ‘Little Lemon’ combines well with other autumnal pleasures such as asters, kales, and fall anemones either in garden beds or containers.

Goldenrods prefer moist, well-drained soils in full sun or partial shade, and are tolerant of wet sites. Plants possess good heat and drought tolerances. Fertilizing goldenrod is rarely needed, but likely will enhance plant vigor.

Goldenrods do not cause hay fever in the fall. The sticky oily goldenrod pollen is to heavy to be carried in the wind. Cut goldenrod flowers are long-lasting and used in dried arrangements.

Clumps need to be divided every 3-4 years. Birds and butterflies frequent flowers often and deer don’t graze on them.

October Starts Out With Fall Sunflowers

Posted by Hugh on September 26th, 2011

Helianthus spp. at Knoxville, TN Garden Center

I thank the person who gave me a native swamp sunflower (Helianthus angustifolia). This long-lived perennial appears to have its own internal clock for blooming around the first day of October. Its long narrow rough-textured leaves average 6 inches in length. The 2-3 inch wide flowers appear first on top of the tall 6 to 7 foot plants, and numerous floral side branches soon follow.

Fall sunflowers are best grown in full sun to insure shorter sturdier plants which need no staking. Plants growing in partially shaded sites do not branch well and produce fewer flowers. If you have no room for 6-10 foot plants, cut them back by half once or twice before the mid- August. Pruning improves branching.

Swamp sunflowers are abit hoggish when it comes to soil moisture. Established plants possess moderate drought and great heat tolerances. Do not fertilize fall sunflowers as they are voracious feeders and tend to need staking, a chore I like to avoid.

In ten years plants have never become invasive in my garden. I suspect the late flowers have not enough time to mature viable seeds. Two other fall sunflowers to select for your fall garden are 18- inch tall ‘Lowdown’ willowleaf (H. salicifolius ‘Lowdown’) and 6-8 foot tall Helianthus x ‘Lemon Lady’.

Helianthus spp. are winter hardy in the Southern Appalachian region (USDA zones 6 and 7). Plant fall sunflowers from March thru July so that plant roots have adequate time to become well anchored and survive the winter cold.

Franklinia Will Survive If…

Posted by Hugh on September 22nd, 2011

Franklinia at NC Arboretum in Asheville

Franklinia (Franklinia altamaha) is admittedly a very finicky large shrub or small tree. Pure white, five-petal, 2 ½ – 3 inch camellia-like flowers bloom sporadically from August thru mid-October. Flowers are slightly fragrant. In the fall glossy green leaves gradually transition to blends of red, orange and burgundy hues.

Franklinia grows best on an eastern exposure site with full morning sunlight and sheltered from strong afternoon sun. Franklinia has a fibrous root system, preferring soil conditions similar to azaleas and rhododendrons. If growing rhododendrons are a challenge, stay away from franklinia. Soil must be compost-rich, excellently drained, and moderately acidic.

Franklinia was named to honor Benjamin Franklin. Originally discovered growing in southeastern Georgia (USDA zone 8), franklinia grows surprisingly well in our cooler Southern Appalachian region (USDA zones 6 and 7). The species is extinct in the wild, but readily available from internet nursery commerce.

Fertilize in early spring with an acidic based soluble fertilizer such as Miracle Gro®, Miracid®, or Hollytone®. Franklinia also favors an annual feeding of Epsom salts (magnesium sulfate) @ 1 Tablespoon per gallon of water per tree. Applying limestone or gypsum anywhere around the feeder roots of franklinia is highly discouraged.