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

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.

Parrotia: A Great Medium-sized Landscape Tree

Posted by Hugh on February 16th, 2012

Persian ironwood mottled bark

Parrotia (Parrotia persica), aka “Persian ironwood”, is native to Iran, Turkey, and the Caucasus region. Parrotia forms a lovely carefree medium sized lawn or street tree. Tree framework is vase-shaped, initially narrow at the base and flaring out in the canopy as it ages. Mature tree height varies 25-40 feet, depending on location and the seedling or cultivar planted. Rated hardy in USDA hardiness zone 5, parrotia excels in the Southern Appalachian region (USDA zones 6 and 7).

Tiny flowers appear in early March and are rarely noticed along its branches. Clusters of ruby red stamens emerge with no petals. In early spring its witchhazel-like foliage starts out reddish-purple and develop into 3-5 inch long leaves. Summer’s lustrous dark green foliage transitions to a blend of yellow, orange and red colors in autumn. Foliage colors are effective for almost a month.

After 12 – 15 years parrotia’s smooth gray bark begins to exfoliate. In subsequent year, a patchwork of green, white, tan and cinnamon unfolds. Prune away lower branches to better catch the striking mosaic bark.

Parrotia is long-lived with no serious insect or disease issues. A two-year established parrotia resists heat, drought, wind, and urban air pollutants. Seasonal leaf colors are more vivid in full to partial (6 hours minimum) sunlight and on a well-drained acidic soil site.

‘Biltmore’ is most popular cultivar which exhibits tall and upright branching. ‘Pendula’ is a spreading weeping mound form only 10-12 feet wide with branch tips which tend to curve upward.

Within the witchhazel family (Hamamelidaceae), besides parrotia and witchhazel (Hamamelis spp.), are such landscape favorites as sweetgum (Liquidambar spp.), fothergilla (Fothergilla spp.) and loropetalum (Loropetalum chinense).

Re-Potting Indoor Plants

Posted by Hugh on February 13th, 2012

Sansevieria (snake plant) rarely needs re-potting

The golden rule for house plant care is to repot them once a year. Times of seasonal change signal the best opportunity for repotting most house plants. September starts a slowdown and March (late February) a re-awakening period for your house plants. Most, but not all plants, should be re-potted in one of these periods.

Purchase a good “house plant” mix (soil-less media) from a local garden shop. Brand is unimportant, although a really “cheap” mix under $3.00 a bag is suspicious from a quality standpoint. The good mix should contain sphagnum peat moss, composted bark, and perlite (or styrafoam). Some manufacturers add vermiculite for improved moisture retention. Specialty mixes should be purchased for cacti and for orchids.

Re-pot plant(s) into the next larger-sized container (measured as pot diameter). For example, 4 ” plant would be shifted into a 5″ pot or 10″ plant into a 12″ pot. Pot may be clay, ceramic or plastic. It is easiest to maintain all your house plants in one type of pot. You may choose to root and shoot prune to keep the plant in the same container.

Partially fill the new pot with potting media. Pry the plant out of the old pot with a knife or thin screwdriver. Gently remove loose soil around the roots and place in a new pot. Slowly work in the new potting soil around to edges. Loosely fill soil to almost the top of pot lip. Watering soil eliminates air pockets and settles the media around roots. Add additional soil as needed.

Finally, do not save unused potting soil more than six months. The “wetting agent” additive has lost its activity. Dispose of the soil in a garden bed and purchase a fresh potting mix.

General Tree/Shrub Fertilizer Recommendations

Posted by Hugh on February 9th, 2012

Fertilizer Aisle at Garden Center

Fertilize most landscape shrubs and trees in winter or early spring with a granular 10-10-10 at a rate of 20 lbs. per 1,000 square feet when the ground cover is dry. A 19-19-19 fertilizer is distributed at 10 lbs per 1000 square feet. Distribute within an area 3 feet out from the trunk or shrub crown and 5 feet beyond the end of the branches. Most of us don’t care to haul a 20 or 40 lb bag of fertilizer from one tree to the next. A one pound coffee tin holds about 2 pounds of fertilizer.

Encapsulated slow release fertilizers deliver the nutrients soil temperatures are warm. Each capsule, called a “prill”, is soil moisture and temperature sensitive. The prill meters out a precise amount of the 3 key nutrients (nitrogen, phosphorus and potassium) over a 3, 5 or 9 month time period. In the warmest areas of the U.S., slow-release fertilizers deliver in a shorter time period. Prolonged drought periods also interrupt prill release. Overwatering meters out fertilizer faster and plants often appear nutrient-starved by late summer.

Water soluble fertilizers such as Miracle-Gro™, Miracid™, Jacks®, Peters®, or Hollytone® are great alternatives. These fertilizers are effective for 4-5 weeks and are usually applied bi-monthly from late March thru mid-August on a 6-8 week schedule.

In most areas spring rainfall is adequate to water the fertilizer in and leach it down to the tree/shrub root zone. Otherwise, you should irrigate to carry down whatever product you’ve applied.

Keep in mind that these are general recommendations and some plant exceptions apply.