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

Native Partridgeberry

Posted by Hugh on February 28th, 2016

Partridge berry at Mt Cuba Center, Greenville, DE

Partridge berry (Mitchella repens) is cherished for its evergreen foliage, spring flowers and fall-winter colorful berries (USDA Zones 4–8). This native groundcover is frequently spotted in moist woodlands along banks of streams and on dry slopes in the eastern and central North America as far west as Minnesota and south to northern Texas and Florida. This ground hugger is a good addition to shade gardens.

Small, four-petalled, tubular white flowers are formed in pairs and are seen spotted above the foliage in mid-spring. Up close, flowers are fragrant; they may re-bloom lightly in fall. Broad rounded half-inch bright green leaves form a dense cover year round on the woodland floor. The leaves are paired oppositely on stems and have a distinctive pale yellow midrib.

Bright red berries that color and ripen in early autumn (in Tennessee) and remain thru winter. Set plants 6-8 inches apart and plan on 1-2 years for this evergreen woody vine to fill in. This non-climbing vine grows barely 2 inches high and creeps tightly along the ground. Stems grab into soil and stone crevices by adventitious roots.

Grow partridge berry in full or part shade and well-drained, acid soil. A soil pH range between 4.5 – 5.5 is ideal. It thrives in moist environs and falters in dry woodland soils. Disease and pest problems are rare.

It is usually propagated by cuttings or seed collected. Vines are collected for Christmas decorating. Partridge berry is frequently seen growing in a cool humid terrarium. Red berries are edible, rather tasteless, but eaten by birds and other fauna. Partridge berry grows abundantly in Newfoundland and Nova Scotia where the berries are used to make jam.

Broadleaved Sedges- Colorful Alternatives To Liriope

Posted by Hugh on February 26th, 2016

3 year old planting of Carex siderostica 'Variegata'

3- year old planting of Carex siderosticha ‘Variegata’

Variegated Broadleaf Sedge

The broadleaved sedges (Carex siderosticha) make terrific alternatives to monkey grass (Liriope muscari) (USDA hardiness zones 6-9). This species of sedges is a clump growing perennial and is starting to become more used as a ground cover. Clumps spread very slowly via rhizomes.

Foliage goes dormant in late November (zone 6) and is semi-evergreen in zones 8-9. New leaves emerge in mid-spring. Utilize it as a groundcover in a rock or woodland garden or edge along a partly shaded pathway. Over time plants grow 8-10 inches high and spread to 15 -18 inches wide.

Sedges grow best in moist well-drained soil and prosper in shade or partial shade in moist, compost- rich, well-drained soil. Broadleaved sedges fail in full sun unless frequently irrigated. A new planting should be kept adequately watered until 1-year established. A densely planted bed will crowd out most weeds. Mow off leaf litter in late winter as new shoots begin to emerge in mid- to late-April.

In early spring feed a slow release fertilizer at the low to medium rate. Avoid excess fertilizing as sedges are not salt tolerant. Sedges have very few disease and pest problems, occasionally aphids, spider mites, and leaf spots.

Green flower spikes appear in late spring and have little ornamental significance. Broadleaf sedges tolerate light foot traffic. They mix well with taller growing hostas, astilbes and many flowering annuals.

3 Cultivars To Try:

‘Lemon Zest’ will brighten a woodland garden. It grows 6 inches tall with 6-8 inch long gold colored leaves in spring, then change to chartreuse in summer.

‘Island Brocade’ displays cream-streaked lime green centers and gold edged. It develops into a dense 6-8 inches tall ground cover.

‘Variegata’ – has distinctive broad leaf sedge 1 ¼ inches wide with pointed tips with white margins and narrow striping and bright white border.

Timing Critical For Applying Crabgrass Preventive

Posted by Hugh on February 24th, 2016

A Weed-free Lawn Is Possible

Crabgrass in lawn before mowing

To control crabgrass and other lawn weeds, 1. maintain a vigorous healthy turf so weeds can’t get established, and 2. apply the proper pre-emergent herbicide at the right time. Pre-emergent herbicides do not kill weeds; they prevent weed seeds from germinating. It’s that simple.

Timing is important! In many states (USDA hardiness zone 5), apply pre-emergent herbicides to lawns against summer weeds by March 15 or winter weeds by September 15. If you live south of the Mason-Dixon line (Delaware and Maryland is south), this means a week earlier. In Atlanta and further south, subtract another week or March 1 on your calendar

Crabgrass seeds germinate when spring soil temperatures warm to 50 °F and higher. What! don’t have a calendar hanging up? If forsythia starts blooming where you live, rush to apply any of following products listed below. All give excellent control of summer crabgrass; fall applications control annual bluegrass in winter:

benefin (Balan, many products labelled “Crabgrass Preventer”)
bensulide (Betasan)
oryzalin (Surflan, Weed Impede)
pendimethalin (Halts, Pendulum)
prodiamine (Barricade, Prodiamine 65 WDG)
Surflan + Balan (XL 2g)

The key is timing of application. Pre-emergent herbicides must be applied before crabgrass seeds germinate. Early fall application should reduce numbers of most winter annual weeds. Lawn and grounds should be irrigated for a minimum of 2 hours within 48 hours after herbicide application.

Date of second application (in Tennessee, southwest VA and Western NC) is usually September 15 for annual bluegrass, henbit or chickweed; these nasty weeds germinate in your lawn and garden in fall and winter months.

Caution: Always read all herbicide labels thoroughly before applying the product. Know what grass species (bluegrass, fescues, ryegrasses, burmuda, zoysia, St. Augustine, centipede) makes up your lawn and what weed(s) you are trying to suppress.

Attracting Monarchs To Your Garden

Posted by Hugh on February 21st, 2016

Monarch on zinnia flower

Monarch on ‘Purple Dome’ aster

From Canada to Mexico, gardeners are being recruited to halt the decline of the Monarch butterfly populations across North America. One way you can help is to fill your garden with Monarch’s favorite flowering nectar plants and milkweeds (Asclepias spp.). Plants should be sited in open full sun and in moist well-drained soil. Avoid spraying pesticides within several hundred square feet of the designated “landing zone” for butterflies.

Nectar plants are the food source that nourishes the adult butterflies. Butterflies feed on their sweet nectar and also aid in pollinating flowers. Select brightly colored flowers which are native to your area. Common nectar plants for monarchs include blackeyed Susan (Rudbeckia spp.), beebalm (Monarda spp.), anise hyssop (Agastache spp.), cosmos (Cosmos spp.), aster (Symphyotrichum spp.), purple coneflower (Echinacea purpurea), lantana, Mexican sunflower (Tithonia), ironweed (Vernonia lettermannia), marigold (Tagetes spp.), tall growing sedums (Sedum spectabile), Joe-Pye (Eupatorium spp.), blazing star (Liatris spp.), salvias (Salvia spp.), and zinnia (Zinnia spp.).

Add specific larval-host feeding plants to attract more butterflies to your garden. Butterfly (adults) lay their eggs on specific larval-host plant species. In the case of Monarch caterpillars, the favorite host plants are the milkweeds (Asclepias spp.) to include common milkweed (A. syriaca), swamp milkweed (A. incarnata), showy milkweed (A. speciosa), tropical milkweed or “bloodflower” (A. curassavica), and butterfly milkweed (A. tuberosa). As its common name indicates, bloodflower is a tender perennial or an annual in zones 9-11.

For maximum visitations, add several kinds of flowering plants with staggered bloom times to keep butterflies coming back to your garden spring thru autumn. The local garden center may offer additional kinds of plants not listed here. On-line nurseries offer species of plants that are rarely found at retail garden centers.

Do your part to help rebuild the monarch population by planting colorful milkweeds and native nectar plants in your garden this coming spring.

Little Girl Hybrid Magnolias

Posted by Hugh on February 18th, 2016

Magnolia x ‘Ann’

Magnolia x ‘Susan’

Star (Magnolia stellata) and tulip (M. soulangeana) magnolias are early flowering magnolias. Early spring frosts destroy open flowers. In the mid-1980’s the U.S. National Arboretum released 8 shrub-type cultivars as a series called the “Little Girl Magnolias”. They are hybrid crosses between M. liliiflora and M. stellata. Four cultivars- ‘Ann’, ‘Betty’, ‘Susan’, and ‘Jane’ – became the popular choices in the series (USDA hardiness zones 4-8).

These hybrid magnolias turned out to be great leaps forward in developing a late flowering magnolias that avoided frost injury. Each Little Girl cultivar blooms in early spring (some places in late spring). Large goblet-shaped flowers are comprised of 6 to 9 inches long strap-like tepals (petals and sepals) and are real eye-catchers.

Flower colors vary by cultivar, in pink to purple shades: Ann (pinkish-red), Betty (reddish-purple), Jane (dark purple), Susan (purplish red). They often surprise with occasional blooms in the summer and early fall. Plants are commonly multi-stemmed large shrubs, but can be trained as small trees. Over ten years these deciduous shrubs will measure 10- 15 feet height and spread.

Little Girl magnolias grow in moist, well-drained soil, preferably an acidic pH, and in full to partial sun (4 – 5 hours minimum sunlight). Roots will not tolerate soppy wet ground. Prune spring flowering magnolias soon after the spring flowering flush is over. Prune to remove basal suckers and to maintain the desired form of the shrub or tree magnolia.

The deciduous leaves are thick and leathery and cope summer heat and drought. With proper care and in the right planting site, these hybrid magnolias are generally long-lived and disease and pest problems are rare.

Changing Bigleaf Hydrangea Flower Color

Posted by Hugh on February 14th, 2016

‘Endless Summer’ Hydrangea

Bigleaf Hydrangea at pH 6.4 or higher

Bigleaf hydrangeas (Hydrangea macrophylla), aka “hortensia” hydrangeas, bear pink flowers in low acidic and alkaline soil and blue flowers in mildly acidic soil. Some tips about regulating soil pH and flower color in bigleaf hydrangeas follows.

First, a short review about soil pH. Soil pH measures soil acidity/alkalinity on a scale of 0-14, with 7.0 being neutral. Numbers above 7.0 indicate alkaline soil while numbers below 7.0 indicate acidic soil. Bigleaf hydrangeas flower blue if the pH is between 5.0 and 6.2. Flowers are pink if soil pH rises to 6.4 and higher.

Flower color is an expression of the amount of aluminum ions (Al+++) in the soil. Aluminum is most available to the plant in acidic soil, and less available in alkaline soil. Gardeners typically purchase aluminum sulfate to lower soil pH. Unfortunately, aluminum toxicity to plants is a big concern because hydrangeas need only small amounts of Al+++.

Garden and shrub beds near cement or concrete foundation walls, sidewalks and driveways, often exhibit low acidic or slightly alkaline soil pH. Over many years limestone leaches from the cement or concrete. While limestone is ideal for most vegetables, flowers or lawn grasses, bigleaf hydrangeas will bloom pink instead of blue.

Pink Flowered Hydrangeas: Gradually add hydrated or dolomitic lime to raise soil pH above 6.2. Be careful on the amount of lime that you add. Above pH 6.4, the quantity of available iron in the soil may become deficient or unavailable to the plant. The hydrangeas take up aluminum best at lower (more acid) pH levels. By raising soil pH, Al+++ is less available to the plant.

Blue Flowered Hydrangeas: For bigleaf hydrangea to flower blue, add aluminum sulfate to garden soil or garden container. Distribute even amounts of aluminum sulfate into soil around the drip line of each shrub. Use of pine needle or bark mulch aids to keep soil slightly more acidic.

Directions: Apply 1/2 oz (1 Tbsp) aluminum sulfate per gallon of water be applied to plants monthly. Irrigate plants immediately following application to prevent burning roots.

Caution: using high amounts of phosphorus fertilizer may result in pink flowered hydrangeas. Soils low in phosphorus and high in potassium bloom more.

Distyliums As Cherry Laurel Or Holly Substitute

Posted by Hugh on February 11th, 2016

Distylium Emerald Heights at Atlanta Botanical Garden

Boxwood like foliage of Emerald Heights Distylium

Hybrid distyliums (Distylium myricoides × racemosum) are compact evergreen shrubs for full sun to partial shade USDA hardiness zones 7 to 9. They are heat and drought tolerant, and are not fussy, growing in average soil with subpar drainage.

Distyliums are members of the witchhazel family (Hamamelidaceae). Their tiny reddish-maroon flowers appear in late January through March, but offer little ornamental value in the winter landscape. Current hybrid selections are favored for their compact growth habit, burgundy new foliage color. Annual growth rate averages 8-10 inches. Distyliums serve as alternatives for time-honored evergreen foundation shrubs such as cherry laurels (Prunus laurocerasus), junipers (Juniperus spp.), hollies (Ilex spp.), and boxwoods (Buxus spp.).

Space plants 2 to 4 feet apart (depending on cultivar and intended use in the landscape) as a specimen, low hedge or a groundcover. In early spring feed distyliums with water soluble (Miracle Gro, Peters, Jacks, or Daniels brand names) or granular fertilizers such as generic 10-10-10 or Holly Tone™ are applied according to package recommendations for evergreen shrubs. Distyliums possess exceptional disease and pest resistances.

These four patented cultivars are now offered:

Blue Cascade® features a matte blue-green foliage with a cascading, layered branching; shrub grows 3 feet wide and 4 feet wide.

Emerald Heights® offers dark green, dense glossy foliage on a compact shrub with upright branching; shrub grows 5 feet tall and 5 feet wide.

Vintage Jade® is a compact, low-spreading mounding shrub with an arched branching habit and dark green foliage; shrub grows 2 feet high and 5 feet wide.

Coppertone® is a medium spreading selection with coppery new spring foliage; shrub grows 3-4 feet high and 4-5 feet wide.

Peace Lily And Anthurium Plants Around Home Or Office

Posted by Hugh on February 8th, 2016

Peace lily (Spathiphyllum)

Red Spathe Anthurium

Peace Lily (Spathiphyllum) and anthurium are near perfect foliage plants in poorly lit areas around your home or office. They’re native to the tropical rainforests of Central and South America. Both plants are shade-lovers in their native habitats. Direct sunlight for more than one hour will likely burn leaves. They’re members of the aroid (Araceae) family, as are many tropical foliage species.

Leaves are glossy, pointed, and oval or arrowhead-shaped. Their spathe-like flowers are unique and beautiful. White (peace lily) or red (anthurium) flowers emerge from the leaf stalk that gradually fade to green or yellow over many weeks.

Peace lily and anthurium are comfortable at temperatures between 60 – 85 °F. In spring and summer, plant(s) can be moved outdoors provided temperature is above 60 °F. Both thrive in high humidity. Locate near a room humidifier during the dry winter months. Another alternative is to set pots on a tray filled with moist pea gravel and spray plants once or twice daily. Never set a pot directly in water or keep soil (potting media) constantly we as this will promote root rot.

Both species prefer a moist well-drained soil and should be watered weekly with room temperature water. Allow tap water, usually from city fluorinated sources, to stand and dissipate away fluorine or chlorine gas over a 24 hour period before watering. Fertilize monthly during the spring, summer and fall with a water-soluble fertilizer such as Schultz®, Miracle-Gro®, Daniels® or Jacks®. Mix at only one-half the label rate.

Repot plants annually. Remove from pot and divide clumps with a sharp knife. Carefully cut apart plant divisions to include healthy roots and leaves. Clip off spent flowers and old leaves. Pot into a sterile well-drained potting soil.

Monthly inspect the underside of leaves for mites or mealybugs. Problem pests are usually found on the underside of leaves where they’re feeding. Prune off heavily infested leaves and spray insecticidal soap to be rid of insects.

Growing Orchids Is A Great Hobby

Posted by Hugh on February 6th, 2016

Lady Slipper Orchid (Paphiopedilum)

Phalaenopsis orchid at Biltmore Estate in Asheville, NC

At one time growing orchids was an elitist hobby for the very rich in our society. Orchids were expensive to purchase. Today, local greenhouses and garden centers sell orchids at affordable prices. Moth (Phalaenopsis) and lady slipper orchids (Paphiopedilum) are the simplest to grow. Here are some easy tips to make home orchid growing a rewarding year-round hobby.

Many orchid species are difficult to grow inside modern homes; not so for the moth and lady slipper orchids. In their natural habitat, orchids are plant epiphytes which grow on tree trunks and branches in the humid tropics. Their thick fleshy roots draw moisture from the air and various surfaces around the roots.

Most important, in northern temperate regions, orchids may spend most of the spring and summer months outdoors beneath the dense leafy canopy of a shade tree in your landscape. In early fall before cold night temperatures arrive (below 40 ºF), plants come back indoors. Orchids are comfortable in home temperatures between 60 and 80 °F.

Low room humidity between 10-40 % during the winter may challenge orchids. Bathrooms and the kitchen are the most humid rooms in a typical home. Group several plants together and set on a tray filled with moist pea gravel. Spray or mist plants daily in winter.

Across the Northern hemisphere outdoor light peering through windows in the winter months is generally lacking. Sunlight intensity is weak and day length is short between November through February. Moth and ladyslipper orchids need only bright light and not direct sunlight.

Orchids should be planted in special potting mix containing coarse bark, sphagnum peat moss and perlite. Some medias add charcoal to improve drainage and filter out impurities. A good orchid potting mix retains moisture only a few days. Otherwise, the fleshy orchid roots begin to rot if growing media stays too wet over many days. Never leave an orchid standing in water over many hours. Annually, repot your orchids after flowering, usually in the spring or in late summer.

Fertilize orchids “weakly” and “weekly” from spring thru fall with a high phosphorus-based soluble house plant fertilizer. Package directions for most house plant fertilizers are too strong for orchids. Use only half the recommended rate and feed weekly. Orchids are fertilized once monthly from December thru February. After repotting, do not fertilize for 2-3 weeks.

Coleus Thrive In Summer Heat And Humidity

Posted by Hugh on February 1st, 2016

Coleus ‘Campfire’ on Ohio State Campus

Coleus flowering in October

Coleus (Plectranthus scutellariodes) is a summer annual treasured for its colorful foliage. Plants thrive in summer’s heat and humidity (USDA hardiness zone 11). Coleus is a member of the nettle family Lamiaceae. You can create dazzling beds of color using coleus alone or mixed with flowering annuals.

Modern day coleus grow more compact and better branched. Trailing forms add another option. Every year new varieties surpass previous color barriers. The color array includes green, pink, yellow, orange, red, purple (almost black), cream, and white. Choose from solids, blended colors, or color-veined foliage.

Most varieties perform best in morning sun and afternoon shade, although shade only types are available. Cultivar series such as the ColorBlaze®, Wizard Sun®, Main Street®, and Ducksfoot® prefer partial to full sun, while the Mosaic® and Kong® series excel in moderate shade. ‘Fish Net Stockings’ struts lime green leaves with dark purple venation.

In northern climes (zones 7 and north), coleus prefers moist, compost-rich soil. Excesses or deficits in soil moisture should be avoided. Plant coleus after the spring frost threat has passed and soil temperatures have warmed above 50 ºF. Light feeding with a water soluble fertilizer such as Miracle-Gro™, Peters™, or Schultz™ every 6 -8 weeks is recommended. For containers incorporate a slow release fertilizer or feed with water soluble fertilizer.

Spacing between plants differs with cultivar size and vigor and this information is usually printed on the plant tag. In general midsize and trailing cultivars should be 16-18 inches apart. Large shade types cultivars should be spaced 24 inches apart unless they’re routinely pinched back.

Over the first 4-5 weeks newly set plants benefit by pinching (light tip pruning) to increase branching and plant density. New coleus cuttings may be quickly rooted from pinched shoots. After 3-4 weeks you can plant rooted cuttings into new garden areas.

Many gardeners opt to pinch off the small flowers to channel energy into plant growth and enhance leaf color and size. Some new cultivars exhibit delayed flower formation.

Scale, spider mites, mealybugs, whiteflies and aphids are occasional pests on coleus.