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

Don’t Let’em Sucker

Posted by Hugh on March 18th, 2012

Crabapple suckering

Some grafted and budded shrubs and trees develop a bad habit to sending up shoots (suckering) from its rootsystem. This creates an untidy appearance around the base of shrubs and trees. Far worse, the root suckers may compete for domination over the cultivar graft. They may rob photosynthate, water and nutrients from the grafted plant. Eventually, the grafted portion may die.

Gardeners select grafted plants for a number of reasons. The grafted cultivar may exhibit more attractive foliage (e.g. Japanese maples, European beech, or purple leaf plum) or better disease resistance (e.g. crabapples, callery pears).

Rootsystems also may have desirable features. Dwarf rootstocks reduce the size of apple trees. Hybrid tea roses are mostly grafted on a rootsystem capable of growing in most soil types.

Sucker growth above ground may be susceptible to fire blight disease, a serious bacterial pathogen which is difficult to control. Aphids, lacebugs, leafhoppers and borers may contaminate wood with serious virus pathogens.

Don’t attempt to spray the sucker growth with a translocated contact herbicide such as Glyphosate ( Roundup™ and other trade names) or Phenoxy herbicides such as 2,4-D, dicamba and MCPP). These chemicals likely will move to the rootsystem to injure or kill the tree.

Powis Castle Artemisia Is Exceptional

Posted by Hugh on March 16th, 2012

'Powis Castle' Artemisia

Most artemisias (aka “wormwood”) can not cope with the summer heat and humidity in the mid-South. Their silvery foliage tends to burn out (some say “melt out”) in mid to late summer. ‘Powis Castle’ artemisia is truly the exception. Powis Castle is likely a hybrid (Artemisia arborescens x A. absinthium

Powis Castle is a bushy, woody-based perennial or subshrub which forms a 2-3 foot high and wide mound. Powis Castle rarely flowers. Its finely divided foliage is evergreen in most gardens in the Southern Appalachian region (USDA hardiness zones 6 and 7). The silvery foliage creates an excellent contrast with green and other colorful leafy plants in the garden.

Artemisias are best planted in well drained soil and in full sun. They tend to grow poorly in soggy winter soils. No soil fertilizing is generally necessary. Diseases and insect problems are of little consequence.

Older plants tend to run randomly because of their rhizomatous root system. Do not cutback artemisias in the fall. Instead, treat them as hardy mums or asters and wait until new spring growth appears before pruning back. Tidy up the garden bed to recapture a fresh new foliage look.

Its aromatic foliage is cut and utilized in creating fresh herbal wreaths and in potpourri. During medieval times wormwood was a popular remedy for whatever ailed you from gout, kidney stones, scurvy and liver problems.

‘Goshiki’ Osmanthus Brightens Up Any Garden Spot

Posted by Hugh on March 13th, 2012

Holly-like foliage of 'Goshiki' Osmanthus

Holly Tea Olive (Osmanthus spp.) comprises a number of evergreen shrubs from Japan which are winter hardy in USDA zone 7- 9. ‘Goshiki’ (O. heterophyllus ‘Goshiki’) is a hardier compact evergreen shrub, which grows very slowly at 3-4 inches per year. It is long-lived, maturing to 5- 6 feet in height and 5 to 7 feet in width after many years.

The Japanese name “Goshiki” translates to “five colors”. Its spiny juvenile foliage mimics American holly (Ilex opaca). New leaves start out with a rosy pink tint, shortly becoming pale yellow and gold flecked over a dark green background. Tiny white flowers in late October are mostly inconspicuous, hidden within the leaf axils. Flower fragrance is very pleasant from several feet away. Tiny bluish black fruit are rarely seen in most years.

Goshiki prefers a moist, well drained and acidic soil. It grows in almost any garden spot from full sun to light shade. Utilize Goshiki in a low front or medium border, a low screen, and a short hedge. Its spiny foliage forms a sharp barrier deterrent.

Goshiki is winter hardy in the Southern Appalachian region (USDA Zones 6 and 7). Osmanthus is mostly pest-free and deer resistant.

Efforts To Solve Japanese Barberry Invasive Problem

Posted by Hugh on March 11th, 2012

'Crimson Pygmy' Japanese Barberry

Japanese barberry (Berberis thunbergii) is a very popular landscape shrub. Japanese barberry is indigenous to Eastern Europe and Asia and is commonly planted in USDA hardiness zones 4-8.

There is justified concern over the invasive nature of Japanese barberry. A number of states have declared most barberry species (Berberis spp.) to be invasive and have banned its future use. Invasive plants may displace and overtake native species, thereby reducing biological diversity. Native fauna populations, which depend on native species for food and shelter, also suffer.

Cultivar selections are very numerous. Shrub sizes may vary from 5 to 8 feet in height and 6 to 9 feet in spread. Foliage colors range from green, yellow, gold, purple, red and variegated types. Dark yellow flowers bloom in early spring, and many set few to large crops of small bright red berries which may persist into the winter.

Japanese barberry thrives in full sun and in any soil that is well-drained. It tolerates urban air pollution, moderate shade, and drought. Japanese barberry is effective as a living fence or hedge in yards and parking areas. It also makes a thorny deterrent against deer.

Current research on Japanese barberry centers on evaluating the seed viability of current cultivars and to breed new sterile (seedless) cultivars. ‘Aurea Nana’, ‘Aurea’, ‘Bagatelle’, ‘Golden Devine’, and Mentor barberry (B. x mentorensis) have a low seed count. ‘Aurea Nana’, ‘Aurea’, and ‘Golden Devine’ sport vibrant yellow leaves, while Bagatelle has red leaves and Mentor has green leaves.

All About Crabgrass

Posted by Hugh on March 8th, 2012

Young crabgrass seedling

Crabgrass is an annual grassy weed which dies out around the first autumn frost. Seeds dropped last summer germinate when the soil warms up from early spring through summer. When spring soil temperatures reach 55-60 degrees (the forsythia shrub is blooming), apply a pre-emergent crabgrass preventative. These herbicides are very effective applied in late winter and again in early July in the Southern Appalachian region (USDA zones 6 and 7).

Some additional lawn care tips to reduce crabgrass infestations:

1.) Spring lawn fertilizing. A thick lawn keeps out crabgrass by making it harder for the crabgrass seeds to sprout. Split apply a slow release lawn fertilizer in late winter and again in mid-spring at the equivalent rate of 2 lbs of actual nitrogen per 1000 sq. ft.

2.) Mow high. A thick, tall lawn grass keeps the soil temperatures cooler and prevents sunlight from lighting the soil. Short mowing weakens the grass, and warms up the soil, making crabgrass seed easy to germinate. Seeds don’t germinate well over shaded ground.

3.) Delay lawn renovation (reseeding bare spots) until fall. In the spring lawn seed germinates in a few weeks, but crabgrass seed comes up faster. Fall seeding is better because crabgrass is dying and new lawn seeding germinates and grows rapidly without crabgrass competition.

4.) Dethatch and aerify lawns in early fall. Crabgrass loves compacted soils. Soil aerification, if needed, is best delayed until fall because you are opening the ground, favoring crabgrass seed germination.

5.) Lime, if needed, in the late fall. Lime raises the soil pH. The proper soil pH allows more nutrient uptake to the lawn grass which means a healthier growing turf.

Outdoor Greenery for Interior Winter Decoration

Posted by Hugh on March 5th, 2012

If you are a new property or home owner, perhaps you’re planning some landscaping this year. Likely, you have several objectives in mind. You might include a few evergreen and deciduous shrubs and trees which, in later years, can be cut for holiday wreaths, garlands, swags and indoor ornamentation. Here is a short list to consider:

American holly (Ilex opaca) — yellow-fruited cultivar pictured)

Winterberry holly (Ilex verticillata)

Canadian hemlock (Tsuga canadensis)

Southern magnolia (Magnolia grandiflora)

Annabelle hydrangea (Hydrangea arborescens ‘Annabelle’)

Limelight hydrangea (Hydrangea paniculata ‘Limelight’)

Boxwood (Buxus spp.)- select from many great cultivars

Summersweet shrub (Clethra alnifolia)

Harry Lauder’s Walking Stick’, contorted filbert (Corylus avellana ‘Contorta’)

Pussy willow (Salix discolor)

There are several other hollies from China and Korea that may substitute. While hydrangea and clethra are not evergreens, the dried spent blooms are very decorative in holiday arrangements. The twisted branches of ‘Harry Lauder’s Walking Stick’ filbert or the furry buds of pussy willow adds any table floral decor over the late fall and winter seasons.

Awaken Overwintering Tropical Plants

Posted by Hugh on March 5th, 2012

Alocasia and Ensete Banana

If you live in USDA zones 6 and 7, early March is usually the proper time to re-awaken containers of tender tropicals stored in your garage or moved in to join your house plants last fall. Likely, they’ve already begun to sprout. Specifically, angel trumpets (Brugmansia spp.), elephant ears (Colocasia spp. and Alocasia spp.), cannas (Canna spp.), and non-hardy bananas (Musa ensete), revive the dormant plant now. Replant into new potting soil, prune off old or dead leaves, and begin a regular watering and feeding program.

Purchase a good porous potting soil (media) from a local garden center. Replace most of the growing media in the old pot or shift up into a larger container. Try not to break many roots if they’ve already sprouted. Tender water garden plants such a tropical water lilies (Nymphaea spp.) and tropical lotuses (Nelumbo spp.) are better planted into drain-free pots containing ordinary garden soil. Soil-less media tends to float out the top when the container is submerged into the water pond.

Feed pots with an 8-9 month rated slow release fertilizer. Rate and directions should be listed on the package. Cover the soil (media) surface with 2-3 inches of large pea gravel to prevent any soil leaving the container and contaminating the pond. When all danger of frost has passed, moved plants outdoors.

Angel trumpets and cannas generally do not flower in the winter months. Replant into fresh soil-less media before moving the container(s) outdoors, about the time you transplant tomatoes in the garden.

The Right Rhododendron for the Right Location

Posted by Hugh on March 2nd, 2012

Rhododendron 'Chinoides'

Rhododendrons (Rhododendron catawbiense) were born in the cool of the North Carolina and Tennessee mountains. Hundreds of lovely hybrids have been bred by dedicated plantsmen. Winter hardiness is rarely an issue, but rhododendrons are challenged by summer heat and disease problems in the Southern Appalachian region (USDA hardiness zones 6 and 7).

Your most important decision is pedigree. So many varieties to try, and the “H-1 ironclad”cultivar class is a good starting point. Here are five: rose pink (cv. ‘English Roseum’), lavender pink (cv. ‘Roseum Elegans’), light pink (cv. ‘Janet Blair’), white (cv. ‘Chionoides’) and dark purple lavender (cv. ‘Lee’s Dark Purple’).

Success with rhododendrons follows three planting rules: sunlight exposure, soil amending, and watering needs. The cultivar must be heat and drought tolerant in summer and pleased with its soil conditions year-round. Direct morning sunlight and mostly afternoon shade are winning combinations year-round. The northeast or southeast corner of a home, garage or large tree serves as an ideal planting site.

The soil must be well-drained, acidic and high in humus. At planting time amend the soil, adding lots of organic matter such as peat moss and compost. Organic amendments tend to lower the soil pH, preferably to 5.5 or lower. After planting fertilize rhododendron(s) bimonthly with an acidic fertilizer such as Miracle Gro™, Miracid™ or an equivalent. Do not feed after mid- August.

Any hint of poor soil drainage generally results in root disease problems like phytophthora and pythium. These fungal pathogens thrive in poorly drained soils. The pesticide treatment costs to attempt to save a pathogen infected rhododendron is high.

Redbuds With Very Few Messy Seed Pods

Posted by Hugh on February 27th, 2012

Ugly Seed Pods on Redbud (C. canadensis)

A few years back my church pastor complained about the ugly load of seed pods covering the redbud branches (Cercis canadensis) on the property in the fall. My suggestion to avoid messy seed pods is to plant seedless redbud cultivars.

A number of native redbud (C. canadensis) cultivars produce few to no seed pods. Let’s start with the cultivars ‘Ace of Hearts’ and sister seedling ‘Little Woody’ which may set fewer than a dozen per tree per year. ‘Hearts of Gold’ (with chartreuse foliage) often sets low pod numbers one year and produces heavy amounts the next. ‘Forest Pansy’ (with dark purple foliage) sets a small scattering of pods annually.

‘Merlot’ is a new glossy wine red foliage redbud from the North Carolina State Redbud Breeding program, and it produces few pods. The pods which form after flowering rarely set viable seeds and the pods abort early. ‘Flame’ is a rare double flowering form, most of which are sterile and the tree sets very few pods.

‘Don Egolf’ Chinese redbud (C. chinensis ‘Don Egolf’) is female sterile and develops no seed pods.

‘Traveller’ (C. texensis) is a weeping redbud hardy to Zone 6 and its flowers are sterile and podless. “I have seen only one pod on ‘Traveller’ in 20 years”, says Dr. Dennis Werner, NCSU Ornamental Plant Breeder.

Start Up A Sleeping Amaryllis

Posted by Hugh on February 20th, 2012

Glorious Potted Amaryllis

Back in the fall, your amaryllis bulb was pushed into dormancy by withholding all watering. In the weeks that followed, the foliage turned yellow and withered. You cleaned off the dried leaves and stored the potted bulb at 34 to 42 °F for the winter, not allowing it to freeze.

After a minimum of eight weeks, preferably longer, has passed, re-start the dormant potted amaryllis by simply adding water. Soak the pot in a trough of warm water for 2-3 hours. For large pots the bathroom tub or kitchen sink will suffice. If several dormant amaryllis bulbs have been stored away, start up one or more weekly to stagger the blooming period. Set the plant in a grow room or a sunny window and water as needed. Rotate the plant every 5-6 days so the emerging amaryllis does not lean (grow) toward the window.

After 6-8 weeks, the flower stalks and some leaves have emerged and stand tall. Usually 3-4 flower buds form on each floral stalk. Several stalks may shoot up, depending on the bulb size and vigor. Fertilize bi-weekly with a water soluble plant food such as Schultz®, Miracle-Gro®, or Daniels® according to package directions (for house plants).

The glorious trumpet shaped flowers bloom for 2-3 weeks and several flower colors are available. After the danger of spring frost has passed in your area, put the plant(s) outdoors on a sunny deck or patio for the summer.

Repeat the dormancy cycle again in the fall when the plant is scheduled to be brought indoors.