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

‘Vanderwolf Pyramid’– Reliable Mid-sized Limber Pine

Posted by Hugh on February 6th, 2013

Winter silver green foliage color of 'Vanderwolf Pyramid'

Limber pine (Pinus flexilis), native to the Rocky Mountain region, has proven to be a reliable landscape evergreen tree in the Midwest and is gaining new fans in mid-South gardens (USDA hardiness zone 7-a). ‘Vanderwolf Pyramid’(VP) is a beautiful dwarf pine being planted by conifer collectors. It is hardy in USDA zone 5, and displays poor heat tolerance in 7-b and further south.

Vanderwolf Pyramid was introduced by New Jersey nurseryman Peter Vermeulen in 1967 and is a real eye catcher. Bluish-green needles are 4-6 inches long, bundled in fives, and are distinctively twisted. VP has an unusually long needle life of 5-7 years. Spring candle growths flaunt electric bluish-green needles which gradually turn a silvery green during winter.

VP has a fastigiate (upright) branching tree form, which tends to open up as the tree ages. VP is a medium-sized pine which matures 30 to 35 feet in height and 15 to 20 feet in width. Young trees transplant reliably, but older trees are less dependable because of a deep tap root system.

In general, limber pine thrives in a moist, well-drained soil in full sun and is tolerant of high pH soils. It has few serious diseases and pests problems, and deer don’t seem to bother it.

VP typically grows slowly at the start and eventually 1 to 2 feet per year. Its common name refers to its flexible (“limber”) branches which bend (give way) under heavy snow loads. The cultivar is commonly grafted onto P. flexilis understock. Utilize as a single landscape specimen or as a privacy or wind screen.

Bright Clivia Flowers Bring Cheer Over A Dreary Winter

Posted by Hugh on February 3rd, 2013

Clivia's Large Orange Flowers In Your Home or Greenhouse

If you’re suffering from the winter blahs, colorful orange clivia (Clivia miniata) flowers will brighten your home. This sub-tropical house plant is native to South Africa, a member of the lily family (Liliaceae), is easy to grow and re-blooms every year as amaryllis or Christmas cactus do. Its wide, strap-like dark evergreen leaves remain blemish free and attractive when not in bloom. The older bottom leaves eventually age and should be removed over time.

Start by purchasing a plant already budded or in flower. Clivia lives a long time as a potted house plant. An older plant will grow 2 to 3 feet tall and wide, and can get large and heavy. Grow in a large, wide-based clay pot that won’t tip over.

Outdoors, clivia grows best in bright daylight, and not in direct sun. It thrives outdoors from late May thru mid-September under a shade tree (USDA zones 6 and 7). Bring tender clivia back indoors when nighttime temps dip below 40 °F. Once indoors, water the plant very little for the next 8-10 weeks. If the leaves start to wilt during “dry period”, supply just enough water to perk them up. If possible, keep in a cool 50 to 55 °F room.

Your good care will reward you with a bouquet of orange lily-like flowers borne in a tall sturdy stem. By early January a thick flower stalk will emerge near the plant base, through the thick foliage.

The orange colored flower variety is most common, but the rare yellow-flowering variety is becoming more available for purchase. Remove the old floral stalk at the base when the flowers fade and wilt.

During the winter months, clivia prefers direct light from a bright north or eastern exposure window. Inside a grow room or greenhouse, do not expose to long periods of direct sunlight. During the spring and summer, clivia needs regular watering, but allow partial dry down between waterings. Do not mist the foliage or keep the potting medium constantly wet, as this may cause rot and promote leaf diseases.

In the spring and summer, regular watering and feeding are the rules. Once clivia has bloomed, fertilize monthly with a water-soluble fertilizer (20-20-20 or equivalent) mixed at 1/2 the rate recommended on the package. Do not fertilize in the fall and winter.

Clivia seem to prefer a near potbound condition. Plant should be divided and repotted every 3-5 years. Repotting can be performed any time after flowering. Set each division in a new 10 inch or larger diameter pot. Use an organically-based potting medium that drains well.

Leatherleaf Mahonia – Love It Or Don’t Plant It

Posted by Hugh on January 30th, 2013

Large Leatherleaf Mahonias at Biltmore Estates, Asheville, NC during Unseasonably Warm Winter

Leatherleaf mahonia (Mahonia bealei), aka Beale’s barberry, is a holly-like evergreen shrub which appears in your garden uninvited. It is a member of the barberry family (Berberidaceae) (USDA hardiness zones 6-9). It has no sharp thorns on the stems, but leaf tips are sharply pointed.

Leatherleaf mahonia is a princely evergreen shrub which blooms in late winter, some years earlier. Clusters of sulfur yellow flowers open above the foliage in terminal racemes starting in late February over a 3-4 weeks period. Lush blue green foliage emerges rapidly after flowering. By late summer the mature leaves feel leathery to the touch.

Leatherleaf mahonia prefers a moist, organically rich, well-drained, acidic soil. It is best planted in partial sun to full shade. Spring’s blue-green foliage often turns pale yellow and leaf margins burn following a dry summer.

This native of China often re-seeds prolifically and has earned an invasive reputation in the South. Grape-like clusters of green fruits adorn this plant from April to July. Fruits ripen to a rich powdery blue color, and birds disperse the seeds around the neighborhood.

Leatherleaf mahonia grows 5 to 6 feet in height. It grows mostly vase shape form, 4-5 feet wide of foliage on top and an open narrow base. Utilize leatherleaf mahonia either alone as a specimen or grouped several as a low hedge, privacy screen, or mound.

Leatherleaf mahonia has no serious disease or pest problems. In my opinion, every 4-5 years, cut this shrub back to the ground immediately after flowering to re-invigorate the planting. Otherwise, it often becomes too crowded in its space. The spine-tipped leaves can be devilish to prune and body protection is advised.

Add Some Gold to Your Landscape

Posted by Hugh on January 30th, 2013

'All Gold' Hakone Grass Planted in Container

Is your garden awash in green foliage? A few well placed bright gold-leaf shrubs or perennials can awaken almost any dull green landscape spot. Here are two shrubs, Mellow Yellow® spirea and Gold Nugget barberry, plus one perennial (‘All Gold’ hakone grass) that may add some flair.

Mellow Yellow® Spirea (Spiraea thunbergii ‘Ogon’) forms small white flowers which cover the branches in mid-spring, and bright yellow narrow leaved foliage soon to follow. Branches take on a drooping habit. The yellow leaves fade to green in the summer, and all leaves turn burnt orange in the fall. It grows 4-5 feet in height and spread in full to partial sunlight. Mellow Yellow tolerates dry soils in summer with little leaf burn.

Golden Nugget barberry (Berberis thunbergii ‘Golden Nugget’) offers bright colored foliage which does not burn in the summer heat. Grow in full sun to sharpen its golden hue. Barberry grows well in average soil as long as it is well drained. The foliage develops an orange cast in the cool autumn air. Golden Nugget is a low slow growing plant for the front border.

All Gold hakone grass (Hakonechloa macra ‘All Gold’) shimmers in a partially shaded spot. Foliage holds its spectacular color all summer, especially when sited in morning sunlight. All Gold grows as a neat, cascading mound, 12 inches high and 18 inches wide. It prospers in compost rich soil with regular watering. Just tuck one or more among green leafy plants and see what happens.

Pruning shrubs shortly after spring flowering as spirea and barberry bloom on last year’s wood. Hakone grass is mowed down in late fall to three inches in height. Bees and butterflies visit spirea and barberry flowers in the spring.

Vernal Witchhazel and New Cultivar ‘Quasimodo’

Posted by Hugh on January 24th, 2013

'Quasimodo' Dwarf Vernal Witchhazel (photo by Highland Creek Nursery, Fletcher, NC)

Vernal witchhazel (H. vernalis) is a dense growing 8 to 12 foot native shrub which blooms in mid-winter in the Southern Appalachian region (USDA hardiness zones 6 and 7). It is winter hardy to zone 4. Small ½ inch wide yellow flowers, flushed red at the base, emit a pleasant witchhazel aroma in the February garden. Often, it’s the fragrance that attracts gardeners to the small strap-like flowers blooming in the winter garden.

New leaves flaunt a reddish purple tint in early spring. The 2 – 5 inch long by 2 – 3 inch wide leaves are medium green and remain pest free throughout the growing season. Fall leaf colors gradually change from green to yellow to gold. Unfortunately, many dead leaves often hang on through the winter, concealing many of the winter flowers. Vernal witchhazel’s root system tends to sucker prolifically. The branch wood displays a pale gray color.

‘Quasimodo’ is a compact 3 – 4 foot high shrub, slightly taller than wide. This diminutive cultivar is an excellent choice for a small garden. Quasimodo was hybridized and introduced by Pieter Zwijnenburg in the Netherlands. Quasimodo drops most leaves in late fall so that its burnt orange flowers are in plain sight in the mid-winter landscape. Winter flowering period may last 3-4 weeks.

Vernal witchhazel grows in full sun to moderate shade and requires little extra care. The soil should be adequately drained and mildly acidic.

Fragrant Honeysuckle Is Long-Lived Heirloom Shrub

Posted by Hugh on January 21st, 2013

Fragrant Honeysuckle on Mid-January Day at Biltmore Estates, Asheville, NC

Old Pruned Shrub at Biltmore Estates, Asheville, NC

Fragrant honeysuckle (Lonicera fragrantissima) has creamy white flowers which open in January during a brief warm-ups and continues, off and on, through February and March in the Southern Appalachian region (USDA hardiness zones 6 and 7). It is an old heirloom shrub indigenous of China. It’s hardy in USDA hardiness zones 4-8.

Fragrant honeysuckle is beloved for its lemony floral scent in the winter. Gardeners cooped up in their homes may force cut boughs indoors. It typically grows 8-10 feet tall and wide, although taller unkempt shrubs are easy to find in old landscapes in the South.

Rounded shaped leaves are 1-3 inches long and tend to hang into late fall with little significant color change. The 1/4 inch green berries ripen dark red in late May and the dark bluish-green spring foliage hide most of them. The bark sheds off in narrow strips.

Fragrant honeysuckle asks for little care and grows in adequately drained average soil. This shrub should be pruned annually from late winter or spring after most flowering is completed. Disease and pest problems are rarely an issue.

Fragrant honeysuckle can be utilized as a low cost deciduous privacy screen. Old plants may be cutback to a few inches above ground with a chainsaw, (called “renewal pruning”), and fed 2-3 handfuls of 10-10-10 granular fertilizer broadcast at least 6-12 inches away from the shrub base.

Information from Mr. John Elsley, South Carolina plantsman: ‘Winter Beauty’ (L. purpusii ‘Winter Beauty’) is a showier winter flowering selection of fragrant honeysuckle. It is a hybrid cross between L. fragrantissima x L. standishii, and has been listed in Hillier Nursery catalog in England. Its winter blooming creamy white flowers are slightly larger and highly fragrant.

Regarding possible invasive issues, fragrant honeysuckle blooms very early when most insect pollinators are not active. Seedlings are rarely found growing around shrubs.

‘Otto Lukyen’ Cherry Laurel Exhibits Better Winter Hardiness

Posted by Hugh on January 17th, 2013

'Otto Luyken' cherry laurel (photo credit- Michael Valk, Evergreen Garden Center, Johnson City, TN)

Otto Luyken (Prunus laurocerasus ‘Otto Luyken’) is a very compact form of cherry laurel. It produces showy, fragrant, erect white spike flowers primarily in the spring, and repeats with light blooming thru the summer months.

Its fragrant white flowers are showy racemes which rise several inches above the foliage in mid-spring. Its glossy pointed tip leaves are steadfast green all four seasons long and exhibit better pest resistance than other cherry laurels in that size class. Presence of shot-hole disease, powdery mildew, and root rot, is mostly the result of poor planting site or exceptionally dry summer weather.

Otto Luyken forms a low foundation specimen or group several into a low hedge. It has a moderate growth rate, 3 to 4 feet high and 5 to 6 feet spread in first 5 years. Utilized it as an evergreen substitute for hollies and boxwoods. Its foliage tends to remain full right to the ground.

Otto Luyken is a relatively low maintenance shrub. It is best pruned immediately after flowering. The black drupes fruits ripen in mid-summer and attract many kinds of birds to your landscape.

Otto Luyken grows best in full sun to partial shade and in a moist well-drained moist soil. Cherry laurel does not tolerate standing water around its base. It copes with an alkaline soil pH, although best in an acidic soil. Its foliage is both salt tolerant and inner city urban pollution.

Skip (Schipka) Laurel Creates Dense Evergreen Privacy Screen

Posted by Hugh on January 14th, 2013

Schip Laurel Screen or Hedge in Johnson City, TN

Schipka laurel (Prunus laurocerasus ‘Schipkaensis’) is a dense growing evergreen shrub with lustrous evergreen foliage and clusters of small white flowers in the spring. It is rated as one of the cold hardiest of cherry laurels (USDA hardiness zone 6-8). In the garden center it is often labeled ‘skip laurel”.

Skip laurel grows 10 to 12 feet tall, and is often utilized as a medium 6 to 10 foot tall privacy screen or hedge through judicious pruning one to two times annually. It grows best in full sun to partial shade and in a moist well-drained soil. Good soil drainage and proper air movement are crucial to avoid outbreaks of potentially serious disease and pest problems.

The handsome evergreen leaves are 2 to 6 inches long and one-half that in width. Foliage is both salt tolerant and holds up to urban pollutants. Skip laurel is tolerant of alkaline soils, but leaf color is darker green in an acidic soil.

Large, upright clusters of small creamy white blossoms lay on 2 to 5 inch long racemes which originate off the leaf axils in late April into May. Many flowers are hidden amid the thick mass of foliage. Flowers often emit an over-powering odor. Small purplish black drupe fruits ripen in late summer and are quickly consumed by birds.

Cherry laurels are indigenous to southeastern Europe and southwestern Asia; schip laurel originates near the Shipka Pass in Bulgaria.

Will The Best Cherry Laurel Please Come Forward?

Posted by Hugh on January 10th, 2013

Cherry Laurel at Bartlett Tree Lab, Charlotte, NC

Not all cherry laurels (Prunus laurocerasus) are created equal. “Skip” laurel (var. Schipkaensis) and Zabel (var. ‘Zabeliana’) are large size shrubs at 9 to 10 feet in height and 6 to 8 feet in width. Both cultivars are rated the cold hardiest of the tall growing types . ‘Otto Luyken’ is the hardiness small leaf form at 4 to 5 feet in height and 6 to 8 feet in width (USDA hardiness zone 6).

Disease and pest maladies abound, primarily when they’re planted in a poor landscape environment and the site problems are allowed to mount up before proper action is taken. Good soil drainage is a must for cherry laurels. Many varieties become riddled with scale insects, stem cankers, and bacterial shothole disease. Extreme summer drought brings on canker and shot hole diseases. Shoddy irrigation practices often worsen the problems.

Diseased black cherry trees (P. serotina), growing wild in fence rows, contribute to the spread of fungal shot hole on cherry laurel cultivars. Defoliation may not always occur even though spotting is visible.

Pruning off diseased branches and spraying pesticide help to reduce or eliminate disease infections. Banner MAXX® or Captan® fungicides at spring bud break protect healthy foliage from fungal shot hole.
Bacterial shot hole is also common in skip and Otto Luyken cherry laurels. Avoid using any one pesticide more than twice in a year to reduce the risk of building resistance.

Witchhazels Invent Their Own Season

Posted by Hugh on January 7th, 2013

Hamamelis x intermedia 'Gingerbread' blooming in February

Witchhazels (Hamamelis spp.) are medium to large shrubs which can be shaped into small trees by judicious pruning. In general, all witchhazels grow in full sun but can prosper with moderate amounts of shade. Other than pruning, they require little extra care. Plant in any soil type as long as it is adequately drained and mildly acidic.

Species native to the Eastern United States include American witchhazel (H. virginiana) and vernal witchhazel (H. vernalis). Asian species include Chinese witchhazel (H. mollis), Japanese witchhazel (H. japonica), and hybrid forms (H. x intermedia). The witchhazel flower color palette ranges from pale yellow, deep gold, copper, and purplish red.

In calendar order, first to flower is Vernal witchhazel (USDA hardiness zone 4). Vernal is a densely branched 8 to 12 foot shrub which blooms from early to mid-winter. Usually, flowering follows a short warm period. Small ½ inch wide yellow flowers, flushed red at the base, emit a pleasant witchhazel aroma.

The Asian witchhazels follow from mid-February thru most of March. Flowers of many new cultivars are larger and brighter colored. Among witchhazels the Asian forms present the widest flower color palette and have increased in popularity as a group

American witchhazel is the last to bloom in October and November in Southern Appalachian region (USDA hardiness zones 6 and 7). This witchhazel grows tall and is frequently pruned into an 18-25 foot tree.

All witchhazels turn pale yellow to dark golden foliage colors in autumn.