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

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.

Pest Update – More Pesticide Options for Hemlock Adelgid Control

Posted by Hugh on January 3rd, 2013

Canadian hemlock short needle foliage

Twenty years ago predictions of the demise of our native Canadian (Tsuga canadensis) and Carolina hemlocks (T. carolina) from home and commercial landscapes turned out to be incorrect. The key reason was the effectiveness of the insecticide Imidacloprid®. This product is licensed by Bayer AG, and is found in a number of lawn and garden products, including Bayer Advance Garden Tree and Shrub Insect Control™ and Merit 75 WP.

Imidacloprid is a systemic insecticide. When properly applied to the soil near the hemlock trunks, it must be carried down into the soil and absorbed through the hemlock roots. The pesticide is applied to the soil Read and understand the easy package directions and watered in chemical within 24-36 hours. Do not expect rainfall to carry it down to roots.

There is even better news. Yearly applications is generally unnecessary. Imidacloprid appears to be more effective than the manufacturer’s recommendations. Hemlock adelgids do not destroy a hemlock tree or shrub hedge in 1-2 years. It may take 2-3 years before serious visual damage is observed.

Other insecticides labeled for use in the landscape may be sprayed to kill the crawler that hatches from the insect egg. Labeled products include Merit (imidacloprid), Talstar (bifenthrin), Onyx (bifenthrin), Astro (permethrin) and Safari (dinotefuran). Talstar is most widely used, providing excellent control any time through the growing season. Control from spraying Talstar has given two and sometimes three years of control. Do not spray trees if the material will drift into open water or other property.

Lastly, Safari 20 SG has slightly faster uptake by the tree as a soil drench or bark spray than products containing imidacloprid. Currently, it is sold only to state certified licensed landscape professionals.

All products are available at garden centers and farm supply stores.

Long-Lived Cedar of Lebanon – A Record Of Human History

Posted by Hugh on January 1st, 2013

Lovely Tufted Needles of Cedar of Lebanon at Arnold Arboretum In Boston, MA

Cedar of Lebanon (Cedrus libani) is a tree aristocrat among conifers. Among the true evergreen cedars it is rated the cold hardiest (USDA zone 5). Its broad horizontal branching and dark green needles defines this tree. The bright green tufted needles are less than 1 inch long and not as showy as the more popular Atlas cedar (C. atlantica) from Morocco.

In its first 25-40 years, cedar of Lebanon takes on a predominantly vertical form. As the tree ages, branching widens and develops its distinctive, flat-topped canopy. Its tufts of 30 to 40 short evergreen needles are borne on short spurs. The 4-inch barrel-shaped cones lie upright on the branches. The cones take two years to mature and disperse seed in late autumn.

Cedar of Lebanon grows slowly, less than one foot per year. The long-lived cedar becomes grander with age. At full maturity, it may reach 60-70 feet in height and spread. Starting out, give it lots of room and a full day of sunlight. The soil should be moist, loamy and well-drained. A large specimen tree demonstrates good heat and drought tolerance, but is susceptible to urban air pollutants.

Cedar of Lebanon is the tree that seems a part of recorded human history from the Phoenician, Egyptian and Roman Empires. Traveling through England, you can’t miss seeing hundreds of lovely tall specimens planted almost 200 years ago, commemorating Napoleon’s defeat at Waterloo in 1815. Efforts are in progress to reforest trees in the geographic area between Lebanon and Turkey where it is indigenous.

Cedar of Lebanon is best planted on park grounds, golf courses, and other large properties. A few dwarf forms are available for purchase from on-line specialty conifer nurseries.

Add A Little Muscle To Your Landscape

Posted by Hugh on December 28th, 2012

American hornbeam at NC Arboretum in Asheville, NC

Underutilized and underappreciated. That’s American hornbeam (Carpinus caroliniana), aka ironwood or muscle wood. It grows primarily in moist, slightly acid soils along woodland rivers and streams. Our native hornbeam possesses the ability to adapt to a range of landscape situations. It grows equally well in full sun or partial shade.

Its dark green summer foliage is rarely troubled by disease or pest problems. Its autumn foliage turns intense shades of yellow, orange and scarlet, depending on soil pH and the provenance of the species. It tolerates either wet or dry soils, but should provide adequate drainage. Hornbeam copes with urban conditions better than most. It survives in tough environs such as non-irrigated planting islands in parking lots. Contrarily, it’s an ideal choice for planting in rain gardens.

Ironwood blooms in spring, with separate male and female catkins. While the male catkins are not particularly showy, the female catkins form unique clusters of winged nutlets that are clearly visible in the fall. The nutlets provide mast for numerous forest fauna. Its grayish fluted bark gives the trunk and branches a muscular feature which is easily identifiable in the winter woods.

Hornbeam grows 20 to 35 feet tall and nearly as wide. The tree often grow multi-stemmed. With clean summer foliage, interesting fruits, good fall color and attractive winter bark, hornbeam makes an excellent specimen or patio tree. It also works as a deciduous green privacy screen.

Triggering Flowering Response In Bromeliads

Posted by Hugh on December 21st, 2012

Brightly Colored Bromeliad at Daniel Stowe Botanical Garden, Gastonia, NC

Bromeliads flower only once. Their brightly colored flowers are mostly “bracts” or modified leaves. Small flowers are nestled within these attractive bracts. Once a bromeliad has flowered it no longer produces new leaves. The colorful bracts (flowers) may last 3 or more months and are cut off once it looks unsightly. Several months later, new young plants, called offshoots or “pups”, form at the base of the mother plant.

The mother plant will form one or several pups at the base. When each pup grows and is big enough, generally 3-5 inches wide, carefully cut off each one with clean razor sharp utility knife or pruners. Plant eachin a separate pot. The pup may require support until few roots have formed. Within 4-6 weeks pups should become better anchored and form the central cup or basin characteristic to bromeliads.

Individual pups may take 2 years or more to reach flowering stage.
In a home environment a young bromeliad may be artificially forced to flower by exposure to natural ethylene gas. An apple or banana gives off ethylene gas as it decomposes. Make certain that the bromeliad’s central cup is dry before starting. The forcing procedure is quite simple: place the plant inside a transparent, airtight plastic bag with a ripe apple for nearly 10 days. Depending on the type of bromeliad you are growing, flowering will be initiated within 6-12 weeks.

Buy This Poinsettia, Perhaps Not That One!

Posted by Hugh on December 19th, 2012

'Ice Crystal' poinsettia

'Jubilee Pink' Poinsettia with New Center Flowers

There are so many colorful poinsettia varieties in stores this holiday season. Some plants will not make it to the first of the year. What attracts you into buying the plant is the colorful bracts (modified leaves).

The “true” poinsettia flowers lie in the center of the bracts. If the yellow stamens are immature or bright yellow, the plant will look lovely through December and most of January. If the stamens appear brown or withered, the bract color(s) will soon fade and show symptoms of decline.

To preserve poinsettia life, give the plant a thorough watering weekly or sooner. Do not leave the plant roots sitting in a saucer or basin of water more than two hours. If the plant is wrapped in foil, it may trap the excess water at the bottom of the plant causing root rot. Punch holes through the foil for better pot drainage.

Set the plant in a well-lighted window in the room. For short term care, fertilizing your poinsettia is unnecessary. Unless you wish to save and grow your poinsettia outdoors next spring and summer, plan to discard it around Superbowl Sunday.

For additional information, review previously written articles on poinsettia care on this website.

Select The Perfect Christmas Tree

Posted by Hugh on December 18th, 2012

Fraser Fir Production in Southwest VA

Decorating a live Christmas tree is traditional in many homes. Many different species of evergreen trees are sold at tree lots near you. Frazier Fir (Abies fraseri) is the most popular Christmas tree in the southeastern U.S.

Named for Scottish botanist John Fraser (1750-1811), it makes its home in the higher mountainous elevations of Tennessee, North Carolina and southwest Virginia. Fraser fir is now produced in northern areas of the U.S. and Canada. Growers ship trees hundreds of miles to tree lots where you live.

Fraser Fir offers a nearly perfect pyramidal tree form, glossy dark green needles, and exceptionally good needle retention. Needles are soft and emit a pleasant evergreen aroma inside the home. Fraser fir is the only fir species endemic to the Southern Appalachian mountain range and grows best above 3000 feet elevation. The mountain climate, soil, and rainfall nurture it for 7-8 years before it is harvested and shipped to a tree lot where you live.

Other tree species grown for holiday trees include balsam fir, Douglas fir, noble fir, Norway spruce, white pine, and white spruce. Leyland cypress is catching on in the deep South. In very traditional homes the red cedar (Juniperus virginiana) is harvested from farmland and woodlots (occasionally from roadsides).

Whatever the tree species you choose, the cut tree should have long needle retention, so that needles don’t wind up all over the carpet before New Year’s Day. Buy a fresh tree, re-cut the butt end another 4-6 inches, set in the tree stand, and water with warm tap water. Check the water level daily and add more as needed.

Happy Holidays!

Growing Bromeliads For Lifelong Enjoyment

Posted by Hugh on December 17th, 2012

Bromeliads at Daniel Stowe Botanical Garden in Gastonia, NC

The bromeliad plant family (Bromeliaceae) includes over 2000 species which live in tropical areas. This includes the pineapple. Bromeliads make great indoor plants. Leaves and flowers come in a wide variety of colors. They are easy to care for and will live for several years. They have very few pest problems.

Some bromeliads are epiphytes which live in trees and not soil. In the home epiphytic species grow on a piece of trunk bark or rough wood boards. Epiphytes have a weak rootsystem and grow poorly in soil. Epiphytes benefit from frequent misting. Terrestrial forms should be potted into a porous potting soil designated for house plants.

Plants thrive in high humid environment such as a greenhouse. Inside the home you should run a small room air humidifier near the plants or set them on a tray filled with gravel or pebbles. Keep gravel moist and do not submerge the base of the pot in water. Group plants together but do not crowd them to increase room humidity. Mist plants 1-2 times daily to raise the humidity around them.

Bromeliads prefer a well-lighted room or bright windowsill, away from direct sunlight. A south or east window is perfect. From late spring until early autumn, bromeliads flourish outdoors in a humid garden environment beneath a large shade tree, away from direct sunlight.

Bromeliads grow well in containers on shady porches and patios over the summer. Exposure to direct sunlight for an extended period of time may result in pale or chlorotic leaves. Poorly lighted plants appear weak or stretched.

They prefer temperatures between 55º F and 80º F, and should be brought indoors when temperatures dip below 40º F. You may water a bromeliad at the central cup, and never pour water soluble fertilizer in the cup. Bromeliads are low feeders, deriving some nitrogen from the air around them.

Water bromeliads once or twice weekly during the active spring, summer and early fall period and reduce watering frequency over winter when plants are mostly dormant. Overwatering is a common mistake.

Bromeliads flower only once and stop producing new leaves. Their brightly colored “flowers” are mostly bracts or modified leaves. Tiny flowers grow within these attractive bracts. The mother plant soon begins to die, but not before developing new young plants called “pups”. Pups grow at the base of the mother plant. Pups are detached from the mother plant, potted, and grown as an individual plant. Individual pups may take 2 years or more to reach flowering stage.