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

Ornamental Peppers Sizzle In Autumn

Posted by Hugh on September 19th, 2011

Ornamental Peppers in mid-September Garden

Some gardeners call them “Christmas peppers”. In the late summer garden all eyes turn away from most flowering annuals and to the colorful fruits of ornamental peppers (Capsicum annuum). Many are dwarf red hot chili peppers. (No!…not the rock band).

Fruits are cylindrical or ball shaped and the brilliant colors range from white, yellow, orange, red and purple (some almost black). Plant foliage may be green, purple, or variegated. Over the years many varieties have been introduced. A popular favorite here in Tennessee, Virginia, and North Carolina is ‘Black Pearl’.

Ornamental peppers are compact growers, 12 -15 inches in height and width. They are planted either in the front of a garden bed or in containers mixed-in among other flowering annuals. Plants display fruits at their spectacular best from late August and thru frost.

Grow ornamental peppers in a sunny garden spot in fertile soils and irrigate plants during long dry spells. Do not over-fertilize (particularly nitrogen) as peppers will produce lots of leaves and few peppers. Disease and insect pests are rarely seen.

Their colorful fruits and foliage make great additions to indoor floral arrangements. Potted plants loaded with showy fruits may also be purchased from Halloween through the winter holiday season. Fruits exhibit a long display life lasting 6-8 weeks.

Caution: keep away from children or pets as the fruit are extremely hot for eating.

Fall Is For Planting

Posted by Hugh on September 15th, 2011

Gardening is part of Outdoor Living

Does your garden need a refresh? Summer’s heat and drought, devastating storms, and disease and pest problems combine to place a pall over your outdoor living space. Perhaps, you desire an entirely new look. Maybe you’re tired of the same old beds of roses, daylilies and other perennials. Maybe your garden saps too much of your time and you seek some low maintenance ideas.

Autumn is a good time to visit a full-service garden center where year- end plant bargains abound. Your first visit should primarily be fact-finding. Do not load up on new plants, but seek out new ideas and solutions. Check out patio furnishings, grills, stonework, or maybe exterior lighting in key areas of your garden.

Shade trees and shrubbery are on sale at 30-50% off, although selection, compared to their spring inventory, is more limited. Spring flowering bulbs are on sale. Bulbs like daffodils, camassias, and crocuses offer many years of floral spring beauty. Tulips and hyacinths are not long-lasting, although 3-4 years is not bad. Mix in bulbs with winter/spring blooming pansies and violas for almost 7-8 months of floral color.

Pinks (Dianthus spp.) are planted in late summer and early fall to take advantage of soil warmth. Plants grow out their rootsystems before winter sets in.

Reminder: guaranteed success with winter blooming pansies and violas sets October 15^thas the key planting deadline. If planted later in the fall, these cold tolerant annuals survive, but their winter flowering is alot less.

Steps in Re-Blooming Last Year’s Poinsettia

Posted by Hugh on September 12th, 2011

'White Winter Rose' poinsettia

Part IV. In mid-September bring plant indoors as outdoor temps start to drop below 50°F to initiate poinsettia flowering. Poinsettia is a “photoperiodic” plant, which means that floral buds and colorful bracts are initiated under short daylengths. A poinsettia requires 6 weeks of 10 hours or less of light per day.

You must be determined to stay with the photoperiodic schedule every day. Exposing a plant to just 1-2 hours more light on any day will keep the plant growing with no flower/bract response.

An alternative way of stating: keep your plant in complete darkness from 5 pm to 7 am for 40 days (6 weeks). Any momentary exposure to light will delay the bloom response. Move into a cardboard box or closet at dusk to block out the room light. Make certain that no direct light seeps in through the cracks.

By mid-November the upper leaves (bracts) should begin to color and flower buds form. Grow the plant at a sunny window and continue to water and fertilize.

Stop fertilizing around mid-December. Continue watering and enjoy your personally grown poinsettia over the holiday season.

Previous Blogs about Care of Poinsettias (dated: Dec. 18, 2010, Dec. 20, 2010, and Jan. 27, 2011)

Re-Bloomers Need Your Help

Posted by Hugh on September 10th, 2011

Encore 'Autumn Carnation' Late Summer Bloom

Re-blooming is an unusual plant trait. Selected cultivars return this time of year for a repeat floral show. In my garden Encore™ azaleas (Rhododendron spp.), re-blooming irises (Iris spp.), and re-blooming daylilies (Hemerocallis spp.) are back for second round of flowering in late summer and early fall.

The gardener/landscaper must supply needed soil moisture and nutrition (primarily nitrogen) so that plants don’t struggle through a stressful summer season. Plants become recharged by frequent irrigation and adequate feeding. In certain situations you may need to monitor and treat a disease and insect problem.

As plants finish blooming in their prime season, remove all spent flower heads to avoid seed formation. For iris prune off old flowers in late May, for daylilies in late June or early July. Encore azaleas bloom in mid-April thru early May and require no deadheading. Timing may vary according to where you garden in the Southern Appalachian region (USDA zones 6 and 7).

In addition, many perennials re-bloom a second and third time after spent flowers are removed and plants are re-nourished. Some easy to grow re-bloomers include: blanket flowers (Gaillardia x grandiflora), perennial salvia (Salvia x nemorosa), tickseed (Coreopsis verticillata), summer phlox (Phlox paniculata), Shasta daisy (Leucanthemum x superbum) and veronica (Veronica spp.).

‘Chocolate’ White Snakeroot Is A Better Choice

Posted by Hugh on September 7th, 2011

Summer foliage (photo courtesy of North Creek Nurseries, Landenburg, PA)

White Snakeroot (Eupatorium rugosum) is native to moist woodland areas in most eastern and midwestern states (U.S.). It grows in average, moist, well-drained soil in full sun to light shade. It is a long-lived and an aggressive perennial. ‘Chocolate’ (E. rugosum ‘Chocolate’) earns its namesake for its chocolaty or burgundy tinted foliage.

‘Chocolate’ white snakeroot grows to a large, shrubby mound with dark bronze leaves and white cottony flowers in early to mid-September. The darkly tinted 4-7 inch long lance-shaped leaves lose most of their chocolaty richness by late summer. The white flower clusters average 6 inches in diameter. Inflorescence sits atop shiny dark purple stems which rise 3-5 feet in height and 1-3 feet in spread.

White snake root spreads by both vigorous rhizomes and reseeding. Deadheading of spent flowers is a must to avoid self-seeding. Self-seeding gives snake root license to become an aggressive garden thug. ‘Chocolate’ does not come true from seed (returns to its wild form).

No serious insect or disease problems. White snakeroot attracts multitudes of butterflies and bees. Flowers are an important source of nectar for transitory butterflies in late summer. White snakeroot should never be planted within reach of milking cows. A poisonous substance in white snakeroot can cause a deathly human milk sickness.

Plant Chocolate white snakeroot where it may be viewed from several angles in border plantings or in naturalized areas.

‘Slender Silhouette’ Sweetgum…Very Few Gumballs!

Posted by Hugh on September 4th, 2011

'Slender Silhouette' sweetgum

Sweetgum (Liquidambar styraciflua) is a medium to large landscape tree, which matures to 65-70 feet in height and 35 feet in spread. To many people it’s called the cursed “gumball” or “ankle twister” tree, not be confused with the fruit balls of the American sycamore or London plane tree (Platanus spp.).

Gumball detractors should look at ‘Slender Silhouette’ sweetgum which produces very few, if any, fruit. ‘Slender Silhouette’ matures to 45-50 feet in height and 12-15 feet in width. Growth rate is rapid at 2-3 feet per year. The cultivar imposes a decidedly vertical architecture to the landscape. The tree’s narrow form makes it a good fit for smaller properties either utilized as a specimen tree or as a tall hedge (green privacy fence).

Foliage is glossy dark green through the spring and summer months. Fall color, which is varies by location and soil pH, ranges from yellow, orange, red, and burgundy. Leaves are 3-5 inches broad with 5, sometimes 7, star-shaped pointed lobes.

Sweetgum is native to USDA zones 5-8, and thrives in the Southern Appalachian region (USDA zones 6 and 7). Bark is light brown and young twigs and branches often form scaly ridges similar to burning bush (Euonymus alata ‘Compacta’).

Landscapers often prefer planting sweetgum over maples (Acer spp.) and ashes (Fraxinus spp.) for its forgiving nature regarding soil type, including on marginally drained clay sites. Sweetgum is not dependable as a street tree where roots may be restricted.

‘Autumn Bride’ Started A Heuchera Evolution

Posted by Hugh on September 1st, 2011

Heuchera villosa 'Autumn Bride'

Autumn Bride heuchera (Heuchera villosa ‘Autumn Bride’) is blooming now. This native ground cover, aka “hairy alumroot”, displays wide lime-green foliage which is not as colorful as many new H. villosa hybrids introduced in recent years. However, the white flowers on Autumn Bride are showier and more numerous.

Heucheras prefer a moist, well-drained, compost-rich soil. Plants are heat and humidity tolerant in the Southern Appalachian region (USDA zones 6 and 7). Grow either in direct morning sunlight in z-6 or in partial shade in z-7. Autumn Bride languishes in deep shade and dry soils and is best grown in a mulched bed.

Autumn Bride and the newer cultivars are not your grandmother’s puny heucheras. Plants are long-lived and vigorous. Leavesappear fairly battered by late autumn and are best cutback along with spent flowers. Feed a handful of 10-10-10 granular fertilizer per plant before growth starts in the early spring. Water soluble fertilizers such as Miracle Gro™, Schultz®, and Espoma® are also good choices. Follow package directions.

Autumn Bride started a heuchera evolution. Planting tips: ‘Autumn Bride’ makes a terrific 1½ to 2 feet tall bedding plant (see photo) when planted en masse. Space plants 2-3 feet apart.

Heuchera villosa are deer resistant.

Gaillardia Survival Depends On Winter Soil Drainage

Posted by Hugh on August 29th, 2011

'Mesa Yellow' gaillardia

In recent years several hybrid cultivars of blanket flowers (Gaillardia x grandflora) have been introduced. Some are annuals and others perennials. This North American prairie native is hardy in USDA zone 5 hardy. Gaillardias should thrive in the Southern Appalachian region (USDA zones 6 and 7), but they don’t! Soggy winter clay soil is their Achilees’ heel.

Gaillardias grow in average well-drained soil under full sunlight. Two-year established gaillardias are heat and drought tolerant. Blanket flowers have a compact mounding habit. Perennial cultivars excel in garden beds or in containers.

Flower colors range from reds, oranges, yellows, and multi-blends, with average bloom sizes between 3 to 4 inches across. Their long flowering period continues from early June through September. Deadheading increases flower numbers.

The cultivar ‘Fanfare’ produces flowers with a dark burgundy center surrounded by red fluted ray petals and flared yellow edges. ‘Fanfare’ is a vigorous grower at 16-24″ in height and 24-28″ in width.

The cultivar ‘Mesa Yellow’ grows 16-18 inches tall and 20-22 inches wide. Their bright yellow flowers form 2-3 weeks earlier than ‘Fanfare’.

Whether the perennial crown survives through the winter is determined by the soil’s drainage capacity. Seedlings from past year’s seed may come back. Plants are deer and rabbit proof, and flowers attract numerous butterflies.

Sunpatiens Worth The Hype

Posted by Hugh on August 26th, 2011

Sunpatiens ‘Compact White’ at Dallas Arboretum

Sunpatiens™ live up to all their hype, with a caveat. They are still impatiens, which means they love (and can’t go without) water. In the Southern Appalachian region (USDA zones 6 and 7), Sunpatiens prosper in direct full day sun to part shade, but can’t go without weekly watering. The flower bed should be mulched and irrigated immediately following planting to shade roots and get transplants off to a vigorous start.

Sunpatiens are best planted immediately after the last spring frost date. This gives them enough time to establish in the landscape before the dog days of summer. Again, the goal is for the foliage to shade roots over the summer. Late plantings in June do not perform as well as late April and May settings.

Plant Sunpatiens in a well-drained, compost-rich soil and feed them with a 5-6 month rated slow release fertilizer at label rates. Established plants grow 36-48 inches tall and 36 inches wide. Setting on 14” to 20” centers will provide an impressive floral display in front of your home or business.

Once planted, it’s critical that Sunpatiens are plugged into a regular irrigation schedule. Extra watering in mid-summer may be necessary when natural rainfall is exceptionally low. Sunpatiens flourish under hot summer heat and tolerate light frost in the autumn. Their thicker flower petals and foliage seem less prone to disease.

Sunpatiens mimic New Guinea impatiens in appearance, but are alot more heat tolerant. At this time color choices for Sunpatiens are limited, with more coming every year.

Kousa Dogwood Not Summer Heat Tolerant

Posted by Hugh on August 23rd, 2011

Kousa dogwood summer foliage

Chinese (Kousa) dogwood (Cornus kousa) rates four stars (out of four) as a beautiful small flowering landscape tree. Since the 1970’s, a deadly anthracnose (Discula spp.) fungus disease has threatened to eradicate our native flowering dogwood (C. florida). Kousa dogwood rates as a highly disease resistant alternative. Its Achilees’ heel is its less than stellar foliar heat tolerance.

In the Southern Appalachian region (USDA zones 6 and 7) most kousa seed-produced cultivars do not handle summer heat issues well. Leaves curl up and reduces photosynthesis. Leaf tips and edges may also scorch. Many of the 100 + kousa cultivars listed in Cappiello and Shadow’s book on dogwoods* are not heat tolerant in the mid-South.

Newly-planted trees are both heat and drought susceptible and should be irrigated the first two years after planting. Cooling the soil by watering helps. Irrigate weekly from mid-June thru early September when summer temps are consistently in the 90’s and natural rainfall is deficient. Drip irrigation keeps kousa foliage dry and disease free while conserving water usage.

A number of U.S. nurseries are currently evaluating several, still unnamed, seedling selections which may be more heat and drought tolerant in the Southeast U.S. landscapes. Expect to see a few at local garden centers in the next 4 – 5 years.

* Cappiello, Paul E. and Don Shadow. 2005. Dogwoods. Timber Press. Portland, OR