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

Floral Fragrance Of Native Fringetree Fills The Spring Air

Posted by Hugh on May 10th, 2013

Native Fringetree Flowering in East Tennessee in mid-May

Fringetree (Chionanthus virginicus) is treasured for its billowy masses of fragrant white flowers in the spring. It commonly grows as a large 15-20 foot tall shrub, but can be easily trained into a 20-25 foot multi-stemmed small tree.

Most gardeners call this native “fringe tree” or fringetree. Regionally, it goes by a number of colloquial names, including “grancy graybeard” (or grandpa’s graybeard) and “flowering ash”. The latter name refers to its close kinship with ash trees (Fraxinus spp.) and lilacs (Syringa spp.) which belong to the same plant family Oleaceae.

Fringetree blooms for nearly 3 weeks, from May into early June in the Southern Appalachian region (USDA hardiness zones 6 and 7). White fragrant flowers spring forth, just days ahead of its large bold textured foliage. The dark green leaves are 3 to 8 inches long and 3 to 4 inches wide, and remain blemish free all summer long.

Most fringetrees are seed propagated which leads to wide variation in fall color. Fall color can be an exceptional bright yellow in some years on particular plants. Others nearby may finish a plain yellowish green color before abcising.

Fringetree is dioecious, meaning flowers are mostly either male or female on the plant. Male flowering trees are said to produce larger showier flowers. The cultivar ‘Emerald’ is a male grafted clone. Female fringetrees bear powder blue fruits in late August. The seeds inside the fruits require 2 years to germinate. It is rare to find lots of seedlings growing in the wild.

Tight clay soils should be avoided and optimal growth occurs in slightly acidic soils. Fringetree grows best in full sunlight with plentiful flowers. In partial shade, the shrub gets tall and leggy, and produces fewer flowers.

‘Thailand Giant’ Elephant Ears A Tropical Wonder

Posted by Hugh on May 7th, 2013

Enormous Leaves of Thailand Giant (photo courtesy of Plant Delights Nursery)

In many areas of the U.S.’Thailand Giant’ elephant ears (Colocasia gigantea) is classified as an annual (USDA hardiness zone 8-10). It grows best in full to partial sunlight (6-hours minimum) and planted in a compost-rich well-drained garden soil or good container potting media. A young plant should be moved outdoors and brought back indoors when night temps fall below 40°F. Thailand Giant may be permanently moved outdoors when night temps are above 45°F.

Thailand Giant grows into a massive 8 to 9 foot tall plant with shiny grayish green foliage. In the garden individual leaves grow in excess of 4 to 5 feet in length and 3 to 4 feet wide if luxuriantly watered and fertilized. Feed with a water-soluble fertilizer such as Miracle-Gro™ or Daniels™ Plant Food, applied bi-monthly from spring planting time until September 1.

Clusters of large fragrant white flowers form at an early age, but are mostly hidden among the enormous sized leaves. The gigantic,tropical looking leaves is the major reason for growing Thailand Giant. Keep the garden soil moist, but not sopping wet. During hot dry summer periods, it should be watered frequently, as much as 2 inches per week.

A few days before first autumn frost, cut back the foliage, dig up the plant, and transplant into a large wide-based container. Store in a cool place (40-45 °F) over the winter and keep soil (potting media) relatively dry. The crown should remain dormant until watering starts up growth in early spring.

Chenille Plant Hot For The Summer Garden

Posted by Hugh on May 4th, 2013

Chenille plant (Acalypha) at Dallas Arboretum)

Chenille plant (Acalypha hispida), aka firetails and redhot cattail, is a hot tropical plant which has jumped from house plant to garden plant use. Their pendulous vibrant red (other colors are available) tassel-like flowers mimic the furry tails of pets. Its lush dark green foliage is heart-shaped. Stems arch downward under the weight of the enormous catkin flowers which may be 4-10 inches in length. In a public garden it is common to watch children walk up and touch them.

Under ideal moisture and tropical warmth, chenille may grow to 8-10 feet in height with a 4 to 6 feet spread. Dwarf and trailing forms of chenille (A. pendula or A. repens or A. reptans) are available. Put these in hanging baskets or let them spill over the edge of a large container. Chenille grows to less than half their garden size in containers.

Add chenille to the middle or back of a sunny perennial border to fill in an empty spot over the summer. It starts blooming in the heat of the summer and continues through the warm days of autumn. Mix chenille with other plants with red hues, such as Red Abyssinian banana, coleus, ‘Strawberry Fields’ gomphrena, among other options.

Chenille grows vigorously. It prefers a moist, well-drained soil with adequate watering through the normally dry summer. Pruning plant(s) back by half in early July develops a compact, more floriferous habit. Occasionally remove spent flowers to keep chenille tidy.

Chenille plant may be grown as a house plant. Cuttings root easily, gathered from plants in the garden. Be vigilant not to invite garden pests indoors in the fall, an easy thing to do. Tropical chenille thrives in a warm humid room with a temperature minimum of 60 °F and full day sunlight. These environmental conditions are best found in a sun room or greenhouse.

Warning: chenille plant belongs to the Euphorbia family; its sap is mildly toxic to people and pets, and may cause eye irritation and dermatitis. Young children are particularly attracted to the bright fuzzy pendulous flowers.

Snow Fountains® Weeping Cherry Fits Small Gardens

Posted by Hugh on April 30th, 2013

Closeup of Snow Fountain Cherry Blooms

Snow Fountains® (Prunus x ‘Snofozam’) is a slow-growing, weeping ornamental cherry that grows compact. It develops into a 8 to 15 feet tall and 5 to 12 feet wide tree. This cultivar is also listed as ‘White Fountains’ in some nursery catalogs. The cascading branches flow downward or may take on a green mound form. This dimunitive weeping cherry is covered with hundreds of pure white flowers in early spring.

The small 5-petalled white flowers attract numerous butterflies and pollinating bees, along with early arriving hummingbirds. A few small black, inedible fruits may develop 4-5 weeks after bloom, and are of no ornamental value. Summer foliage is dark green, and the 3-inch and longer leaves develop autumn blends of golden or orange before falling.

Grow in a medium moist, slightly acidic, well-drained soil. Plant Snow Fountains (or any cherry cultivar) in full sun and do not overcrowded for good air circulation to insure disease free growth. Prune when necessary after spring flowering to shape and to remove diseased and pest-ridden twigs and branches. Borers and stem cankers can be significant problems when the tree is environmentally stressed.

Aphids, caterpillars, Japanese beetles, and scales continue a possible litany of pest problems. Fungal and bacterial leaf spot diseases may lead to holes in the summer foliage. Utilize appropriate pesticides as needed.

Most varieties of weeping cherries grow very tall and wide for small landscapes. Snow Fountain grows a lot more compact and is an excellent planting option for small urban sites.

‘King Tut’ Papyrus Adds Texture To The Summer Garden

Posted by Hugh on April 27th, 2013

: Standard sized Papyrus in Flower Bed at Kingwood Center in Mansfield, Ohio

Over thousands of years papyrus (Cyperus papyrus), aka Egyptian paper plant, was essential for food, medicine, fiber and shelter in ancient Egypt. Today, we utilize papyrus, as many other aquatic and bog-like plants, to add texture to the garden. Papyrus is classified as a non-hardy sedge (winter hardiness to USDA zone 9).

Invite this lovely exotic from the African continent into the summer garden or into a container on your patio or deck. It’s perfectly happy growing with its feet in water, and will prosper in garden soil under frequent drip irrigation. Papyrus grows at the edge of a water garden or ponds, in boggy soils, or in standing water in containers. Optimum growth is in full sun, but it tolerates partial shade. This incredibly fast grower will add 5 to 8 feet in a single season.

‘King Tut’ is a dwarf 4-5 feet tall cultivar. Its leafless green triangular stems stand tall and rigid at 2 to 3 feet high. Inadequate sunlight may compromise stem sturdiness. Roots are woody rhizomes which anchor the plant in a garden soil or container gravel medium. Papyrus does not suffer from serious insect or disease problems.

In the Southern Appalachian region (USDA zones 6 and 7), plants must be potted up and brought indoors before frost for winter care. Maintain at 40° F minimum temperatures and high humidity in a mostly sunny window, a sunroom, or a greenhouse.

Invite this beautiful Egyptian water plant into your garden. Garden centers often sell papyrus in their aquatic supply department or purchase from an e-commerce nursery on-line.

‘Shaina’ Japanese Maple

Posted by Hugh on April 23rd, 2013

'Shaina' Japanese Maple at Atlanta Botanical Garden in April

The foliage of ‘Shaina’ Japanese maple (Acer palmatum ‘Shaina’) starts out hot red in early spring. The deeply cut leaves are bunched together for a tufted or layered look. From mid-spring thru summer, the foliage, now maroon red, holds its color.

Shaina grows naturally as a shrub, 8 feet high and 4 to 5 feet wide in 10-12 years. Some nurseries sell it in tree form, but it must be judiciously pruned to maintain this shape. Non-showy reddish flowers appear in May and contribute little in ornamental value.

Japanese maples should be plant in the right location, protected from high winds, and irrigated as needed. They grow in compost-rich, well-drained soil in full sun to partial shade. In more southerly locales, plant them in a full-day, partially shaded garden spot (USDA hardiness zones 6-9).

In general, Japanese maples contract few serious disease or pest problems. Stem canker maladies may arise if improperly sited or environmentally stressed. In northern areas spring foliage may pop out early and be injured by late night frosts. Covering with a cloth tarp is advised when frost warnings are posted in your area.

Shaina is a lovely understory shrub with attractive red foliage and plant form. Plant it as a specimen or a container accent plant near your home patio where guests can take notice.

Why Peonies Do Not Bloom

Posted by Hugh on April 20th, 2013

Herbaceous Peonies In May Garden

Herbaceous peonies (Paeonia x lactiflora) are among the easy to care for and long-lived garden perennials. If you plant them correctly in compost rich, well-drained soil and a minimum of 6 hours of sunlight, they will bloom for the next 30+ years. If peonies fail to bloom, here are 8 probable causes:

1. Planting crowns too shallow or too deeply. Proper soil depth from the top of the crown is 2 inches.

2. Proper planting date – plant anytime from late August thru November in the Southern Appalachian region (USDA hardiness zones 6 and 7). Container plants may be planted anytime and do not to disturb the tender fibrous roots unless badly potbound.

3. Buy strong 3-eyed or more peony crowns from a reliable peony source on-line or local garden shop.

4. Inadequate sunlight – plants full sunlight or at least 6 hours daily (USDA hardiness zones 4-7a). Shade from harsh afternoon sun in zone 7b).

5. Overcrowded plants – Space 3-4 feet apart to prevent plants from competing for light and soil nutrition. Overcrowding increases disease pressure, particularly leaf spot diseases such as Botrytis blight and Phytophthora stem blight. Flower buds do not open, turn black and drop off weeks later.

6. Too much nitrogen fertilizer – Peonies tend to feed constantly through the growing season. A slow release fertilizer applied in late winter is more than adequate.

7. Deficient Phosphorus (P) and/or potassium (K) in the soil. Both nutrients initiate flowering in peonies.

8. Late spring killing frost injure unopened floral buds. Protect tender flower buds by placing a cloth, not plastic, tarp or blanket over plants.

Summer Flowering Heleniums Should Not Make You Sneeze

Posted by Hugh on April 18th, 2013

Helenium 'Moerheim Beauty'

Helenium, named for Helen of Troy from Greek mythology, is U.S. prairie perennial. In times past powdered disk flowers and leaves of some heleniums were used as snuff, hence the common name. It’s difficult to sell ‘sneezeweed” and many garden catalogs now list it as “helenium”. A number of good hybrid selections have been introduced including Moerheim Beauty (Helenium ‘Moerheim Beauty’) and Mardi Gras (H. x ‘Mardi Gras’).

Moerheim Beauty stands 2 ½ to 3 feet tall and 1 to 1½ feet wide on sturdy stems. It develops deep roots, and rarely needs staking as many seed varieties do. The showy 2-inch wide coppery red ray flowers surround a dark dome-like center. Flowers gradually fade to burnt orange.

Mardi Gras grows slightly shorter and bears bright fiesta-like yellow petals, splashed with orange-red over 6-8 weeks from mid- to late- summer. Petals age to clear red with a gold edge, all surrounding a dark brown button center.

Heleniums grow in full sun and in an average moist, well drained soil. They tolerate wet, sometimes flooded soils, and are great choices for rain gardens. Long summer dry spells can devastate the foliage and flower count, and they should be watered regularly. Flowers may sometimes be nipped by an early autumn frost in USDA hardiness zone 5 and colder.

Fertilize sparingly to prevent weak stems and crowns, and the need for staking. Plants may benefit from being cut back in late spring to encourage branching and more flower formation. Deadhead old blooms to encourage additional ones. Crowns should be dug up and divided every 2-3 years.

Flowers attract many kinds of butterflies; deer and rabbits stay away from toxic heleniums. Plant heleniums in flower borders and meadow gardens. They look great growing in containers and their sturdy long stems and a long vase life make them great cut flowers. Above recommended cultivars exhibit exceptional disease resistance.

A Marigold Revival

Posted by Hugh on April 14th, 2013

Marigolds and Ageratums at Kingwood Center, Mansfield, Ohio

Over the past 2-3 years marigolds are regaining their popularity. Marigolds are easy to grow and come in vibrant shades of yellows and oranges. Tall African type marigolds grow 24-42 inches tall and belong in garden beds. Intermediate (15-24 inch height) and dwarf French types (10-12 inch height) are suited for both bedding and container plantings.

Plant marigolds in full open sunlight and do not crowd or overwater plants. They require very little maintenance if planted in compost-rich garden soil that is well drained. Marigolds handle summer heat and short dry intervals if they have been properly cared for the first six weeks after planting. A well established bed of marigolds will bloom non-stop through the summer into autumn.

Marigolds are best planted in early to mid-May in the Southern Appalachian region (USDA hardiness zones 6 and 7) after the spring frost period has passed in your gardening area. Marigolds are great as late garden fillers where other flowers may have fizzled out. You may plant marigolds up to mid-August and they will bloom up to the first hard freeze in October or November.

Feed with a granular 10-10-10 fertilizer or a water soluble products such as Miracle-Gro®, Jack’s Classic®, or Daniels® fertilizer at package directions.

Their principal nemesis is spider mites which are easily eradicated with environmentally mild pesticides. Botrytis is a flower disease best prevented by selecting varieties that shed water and by not watering overhead. Short French type marigolds are known to repel insects in vegetable gardens with their strong fragrance. You must plant large numbers of marigolds which will cut down space veggie beds.

Recommended cultivars:

‘Perfection’ series @ 30 -36 inch tall and 15 inches wide.

‘Marvel’ series @ 18 inch tall by 10 inches wide.

‘Moonsong Deep Orange’ @ 15 inches tall by 10 inches wide.

Moonstruck Series @ 12-15 inches tall

Bonanza series (French type) @ 10-12 inch tall

Cool Blooming Osteospermums

Posted by Hugh on April 11th, 2013

Osteos at UGA Gardens in Athens, GA

Osteospermums (Osteospermum x hybrida ) are members of the daisy (Asteraceae) family, commonly called African Daisy, Blue-eyed Daisy, or Cape Daisy. Osteos are cool season annuals that excel in northern and less so in southern U.S. gardens. Osteos bloom more profusely in full sun, but want some cooling relief during the summers.

Osteos have always been a popular cutflower, but are now becoming a annual bedding plant. They should be planted early with petunias and million bells (Calibrachoa). The heat of summer knocks osteos out of bloom, but they often recover to bloom again in late summer. Keep them adequately watered the first month after planting.

Flat daisy-like petals radiate out in a tubular or spoon shape. Every year new color choices continue to win over gardeners. Plant breeders are improving summer heat-tolerance and introducing more compact growing cultivars. Color choices abound from lavender, pink, white, yellow and bi-color, with more introduced every year. Their dark green foliage may vary with the cultivar from lance- , ovate, and/or lobed- shaped.

They prefer an acidic soil, but perform well between 5.5 to 6.5 pH. Feed osteos on a bi-weekly basis with a water soluble fertilizer such as Miracle-Gro™, Jack’s™, or Schultz™ according to package directions. Although drought tolerant once established, osteos need one inch of water weekly to look their best.

During periods of intense heat and drought, growth slows or plants go dormant. Cut osteos back in late summer to stimulate new stems and leaves. Remove wilted flowers and old worn foliage to induce new flowering.

Osteos are super performers in hanging baskets and window boxes. Cultivar series vary from 12 – 36 inches in height by 12 – 24 inches in spread. Among the popular osteos are the Voltage®, 3D®, and Margarita® series.