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

Making A Case for Mugo Pine

Posted by Hugh on November 4th, 2011

'Mops' Mugo Pine at New Hope Garden Center, Blountville, TN

Mugo pine (Pinus mugo) is a slow growing needle evergreen shrub of variable heights ranging from 5 feet to 20 feet and more. Mature height depends on the cultivar planted and environmental conditions on site. Mugo pine is native over many hundreds of miles of alpine climes across Europe. It is winter hardy in USDA zones 3-7, but its heat tolerance in southern parts of zone7 is sub-par.

This shrub pine grows best in full sun, but can tolerate light shade. The key to successfully growing mugo is a moist well-drained loamy soil. Planting in wide shallow holes on raised bed(s) is highly recommended. Mugo has a disease prone shallow rootsystem. Add mulch to keep roots moist and cool. Two-year established mugo pines exhibit good summer drought tolerance.

The 1-2 inch long dark gray/blue stiff needles are borne in bundles of two. The densely packed needles exhibit a long 5-6 year retention life before succumbing to natural needle drop in early fall.

There is great variability among mugo pines in terms of growth rate, size and shape. The popular variety ‘pumilio’ often grows beyond its stated size and form. ‘Mops’ is the preferred dwarf cultivar, growing 3-5 feet tall and 5-6 feet wide. ‘Mops’ may be utilized as a groundcover, included in a low foundation planting, or set in a rock garden. Selected hand pruning of young developing shoots (“candles”) in late spring may dwarf ‘Mops’ or other cultivars even further.

Mugo pine is susceptible to root rot diseases in poorly drained soils. Pine sawflies and tip moths are key insect pests. Quick monitoring and spraying with acephate (Orthene®), cyfluthrin (Bayer Advanced Garden Multi-Insect Killer®), or carbaryl (Sevin®) insecticides will keep these serious pests in check.

‘Snow Flurry’ Zone 6 Hardy Camellia

Posted by Hugh on October 31st, 2011

Fall Blooming 'Snow Flurry' Camellia

‘Snow Flurry’ camellia is a broadleaf evergreen shrub with good plant vigor. It was one of the first zone 6 cold hardy camellias hybridized by Dr. William Ackerman and released by the U.S. National Arboretum in 1986.

Snow Flurry grows into a 4 feet tall by 6 feet wide shrub over a 10 year span. Branching is mostly upright with branch tips bending downward, mostly from weight of the numerous flowers produced. The medium-sized (3 ½ inch) white flowers open in early autumn. Flower shapes may vary from peony to anemone types on the same shrub.

Camellia culture is similar to rhododendrons. Camellias prefer partial sunlight (6-hours minimum) for optimal flowering. Garden soil should be moist, well-drained, and slightly acidic. The planting site should be generously amended with peat moss and /or compost. Plant shrub(s) shallow in a wide planting hole, slightly above soil grade, and spread 2-3 inches of an organic mulch around each shrub. The planting site should be partially sheltered from winter’s desiccating winds and direct afternoon sunlight year-round.

Camellias require little to moderate pruning annually, depending on the cultivars grown. Pruning is best performed in mid to late April before new vegetative growth begins. Newly planted shrubs are drought susceptible, but two-year established camellias tolerate summer dry spells well. Their lustrous green foliage is tolerant of coastal sea salt spray.

Fertilize with acidic- based plant foods such as Hollytone™, Miracle-Gro™ and Miracid™. Follow package directions and don’t fertilize camellias after August 15^th.

Currently, disease and insect problems are almost non-existent in zone 6 areas of the Southern Appalachian region (USDA zones 6 and 7).

Irrigate Evergreens This Winter

Posted by Hugh on October 28th, 2011

Spruce Container at Biltmore Estate, Asheville, NC

Fall slowdown in the garden brings many of us back indoors to prepare for the winter holidays ahead. A number of serious canker diseases attack evergreens in the fall and winter if soil moisture is not plentiful. These diseases include botryosphaeria, cytospora, phomopsis, and seiridium cankers. Each organism is capable of causing branch dieback or death to the entire shrub or tree.

Evergreens such as laurels, rhododendrons, spruces, Leyland cypress, upright junipers, and arborvitae are the most susceptible. In late fall, around Thanksgiving, deep watering of evergreens in the ground is generally good insurance against disease. Weekly watering entails supplying 1 inch of natural precipitation (rain or snowfall equivalent) and/or irrigation.

A gardener should be aware of the natural environment. In particular, needle conifers in containers may be in most jeopardy of the winter weather ahead. Wintry winds may desiccate needles rapidly. An evergreen’s umbrella-like branch canopy reduces the amount of rain and snowfall that reaches the root mass in the container.

Containerized evergreens in the Southern Appalachian region (USDA zones 6 and 7) should be watered every 8-10 days over the winter months. Container media may freeze solid for a few days during winter cold snaps, but the media thaws out and the plant re-hydrates. A fully hydrated plant is better able to cope in frozen media than one in drycontainer media.

Evergreens should be transplanted into larger containers and fresh media every 2 to 3 years.

Credit: Information supplied by Dr. Alan S. Windham, Extension Plant Pathologist, University of Tennessee, Plant Diagnostic Lab, Nashville

Natural Evergreen Needle Drop in Autumn

Posted by Hugh on October 25th, 2011

Natural Needle Fall in Pine in October

Some needle loss on evergreens in the fall is natural. As night time temperatures cool, needles in the interior of many evergreen trees or shrubs regularly turn brown (or golden yellow) and drop off. Needle loss is most obvious on pines (Pinus spp.) and arborvitae (Thuja spp.) in the Southern Appalachian region (USDA zones 6 and 7).

The numbers of needles shed may vary from one year to the next. Unusually high needle losses may be a reaction to high summer heat and extended dry periods within the geographical area where you live.

Loss of two year and older needles is natural. Loss of current season and last year’s needles is painfully not a good thing and may be caused by a disease or insect pest. Roots of evergreens may contract a root disease such as pythium and phytophthora fungi. Often, a root disease may be fatal or the pesticide treatment(s) very costly.

Environmental and transplanting stresses may be the cause. Winter desiccation and de-icing salts can turn evergreens brown. Needle losses are usually higher on newly planted evergreens.

Weekly deep watering in the fall and late winter fertilizing of evergreens helps relieve transplant stress. Transplant shock (heavy needle loss) should not re-occur the following fall.

Note: More on fall-winter care of evergreens coming soon.

Alaska Cedar Is Awesome Weeping Evergreen

Posted by Hugh on October 21st, 2011

Alaska Cedar at Kingwood Center, Mansfield, Ohio

Over the past decade, gardeners have been planting different evergreen trees in their Southern Appalachian landscapes (USDA zones 6 and 7). One of the newbies is Alaska cedar (Chamaecyparis nootkatensis), a wonderful medium-sized evergreen tree from the west coast of North America.

Alaska cedar matures into a graceful pyramidal tree form. Long pendulous flattened sprays of bluish green needles drape from the mostly horizontal branches. Needles turn grayish green in winter. Tall (40-50 feet) and narrow (15-25 feet) in stature, Alaska cedar is long-lived and a slow grower until established. It grows best in full to partial sunlight (6 hours minimum) in a compost rich, well-drained soil. A newly planted tree benefits from weekly irrigation over a hot, dry summer until fully established in three years.

Dense evergreen foliage conceals the reddish brown shredding bark within. Bark on an older trunk and branches appears ragged and gray colored. Flowers and ½- inch diameter seed cones are insignificant and require little cleanup. Alaska cedar has no serious disease or pest problems.

There are over 15 selections of Alaska cedar in nursery commerce. ‘Pendula’ (more weeping form), ‘Green Arrow’ (narrow) and ‘Van den Akker’(very narrow) are popular cultivars. Plant any one of these fabulous Alaska cedar cultivars nearby a deck or patio where it likely will become a major focal point in your landscape.

Alaska cedar has recently been reclassified as Cupressus nootkatensis.

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.