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

Keep Your Eye on Red Buckeye

Posted by Hugh on March 25th, 2017

Red buckeye (Aesculus pavia)

Red buckeye (Aesculus pavia) is shrubby or low branching tree maturing to a 15 – 20 feet in height and spread. This southeastern U. S. native is becoming more recognizable as a good choice as a landscape tree for a small urban garden. Plant the tree in either full to partial sunlight and in average well-drained soil.

A tree may develop flowers when it is young in late April and May. Numerous 5 to 9 inches long floral heads sit at branch tips like decorative candles. Bloom count is highest in full day sun. Flowers open slightly before leaf emergence. Flower color on individual trees varies from dark pink to scarlet red. A yellow flowering form is known to exist. Hummingbirds arrive in time to pollinate the individual tubular blossoms.

Lovely palmate compound dark green leaves clothe the branches in spring thru early summer. In late September the broad seed pods split open exposing polished dark buckeye seeds; they drop from the tree, and are quickly grabbed up by squirrels and other garden critters. Don’t be surprised to find a young seedling or two germinating somewhere in the landscape in the years ahead.

Several disease and insect problems riddle the foliage; dry and hot summer weather will often scorch leaf edges unless irrigated weekly. Leaves succumb to the disease and weather onslaught resulting in premature leaf loss beginning in mid-August. Count on no autumn foliage color as branches are typically bare. Spraying pesticides to prevent diseases and insects is unnecessary. New flowers and foliage emerge unharmed the following spring. Deer and rabbits do not trouble this tree.

Pruning, if needed, is performed in mid-spring, right after flowering. Feed the tree lightly with 10-10-10 fertilizer (or equivalent) either before or following spring bloom.

Basic Care Tips In The Spring Perennial Garden

Posted by Hugh on March 22nd, 2017

Coreopsis, Shasta daisy and Beebalm Summer Display

Echinacea x ‘Cheyenne Spirit’

In late winter – early spring, after the snow has melted and daytime temperatures are steadily above freezing, let’s get busy with the cleanup in the perennial garden. First, if you garden in a severe winter region such as zones 4 or colder, remove all winter protection such as evergreen boughs or protective mulches. Many perennials need sunlight as they peak through the ground.

All leaf and twig debris, dead flowers, stems and seed heads should be pruned off. Perennials, such as tickseed (Coreopsis), shasta daisy, garden phlox, asters, and coneflowers (Echinacea), form green rosettes; new flowering shoots will sprout up as sun and warm temperatures reach them.

Weeding garden beds should be your next chore. It may be difficult not to confuse weeds from newly emerging perennials. Follow-up with fertilizing and mulching garden beds. Organic-based slow release fertilizers are preferred as nutrients are metered out over the growing season. Avoid fertilizing plants if the foliage is wet so as not to burn the tender spring growth.

Apply 2-3 inches of pine bark or pine straw mulch near plant but don’t pile mulch around the plant base. Using compost as mulch supplies nutrition for early spring wildflowers such as bloodroot, primula, Virginia bluebells, trilliums and many others.

If needed, divide or transplant newly emerging perennials in the early spring. It’s best to divide most perennials when they are about 2 to 4 inches tall. Never move or divide perennials when they’re flowering. A certain number of perennials are best divided after they bloom. That list includes hostas, oriental poppies (Papaver), Siberian iris, bearded iris, lilies (Lilium) and daylilies (Hemerocallis). Peonies are best divided in the fall.

You may need to stake tall growing perennials using cages or hoops for peonies, Joe Pyes (Eupatorium spp), and baptisias (false indigo). Remove spent flowers from tulips, daffodils, and other spring-flowering bulbs, but let the foliage to die down naturally. Think of bulb leaves as solar collectors to replenish food energy in the bulb for next spring. Do not braid the leaves.

Winter Daphnes Can Be A Rewarding Challenge

Posted by Hugh on March 20th, 2017

Daphne odora ‘Aureo-marginata’

D. odora ‘Aureo-marginata’

Native to China and Japan, winter or fragrant daphnes (Daphne odora) open to light pink or white flowers in winter and early spring in the southeastern U.S. and Pacific Northwest (USDA hardiness zones 7-9). Their welcome floral fragrance will pervade through your garden for nearly two weeks starting in late winter.

Winter daphnes grow 3 to 4 feet high and spread. Flowers, mostly available in white and pink, are produced in small clusters on stem tips. When possible, place daphnes near a patio, deck or walkway where its floral fragrance can be enjoyed.

Glossy dark green leaves are leathery, evergreen, and vary from 1.5 to 3.5 inches in length. Variegated cultivars are edged either white or gold. On a rare occasion, plants bear fleshy non-edible red fruits which are few and far between.

Planting site must be exceptionally well-drained, be generously amended with compost, mildly acidic soil (pH 6.0-7.2), and kept adequately watered. Daphnes are notoriously finicky shrubs and don’t tolerate dry or poorly drained sites. Overwatering leads to their rapid demise. Plants also flourish in containers when properly cared for.

Set in one-half day, preferably in the early morning hours or in dappled shade. Daphne leaves will sun scorch when not adequately shaded. In warm climate zones, the further south you live, the plant should see less afternoon sunlight. Daphnes require only minimal pruning and spring is a good time, anytime after flowering.

Aphids and scale insects are occasional pests. Root rot, crown rot, and leaf-spots are fungal diseases, mostly caused by poor environmental growing conditions.

Leading varieties:

‘Aureo-marginata’ – rosy-pink flower buds that open to white with slight cream-colored edge leaves.

‘Alba’ – white flowering form.

‘Zuiko Nishiki’ – green leaves, heavier bloomer than species, more fragrant, and reportedly is hardier.

Annual Flowering Vines

Posted by Hugh on March 17th, 2017

Exotic love vine (Mina lobata)

Thunbergia ‘Sunrise Surprise’

This spring try vertical gardening. There are a number of annual flowering vines that grow in either the ground or in a large container. Some offer cooling shade on a deck or patio. Vines are highly ornamental with attractive flowers, foliage, and/or fruits.

Annual vines grow quickly after planting. Plant seeds of these vines at the base of the trellis as soon as soil has warmed in April and May. For a dense cover, space seedlings 6 to 12 inches apart. In northern areas, where growing season is short, some vines like morning glory and hyacinth bean vine should be started from seed indoors and transplanted outside when threat of spring frost has waned.

Most annual vines climb by twisting around a support. Some attach themselves by means of wrap-around tendrils. Trellises come in many shapes and sizes, constructed of wood or metal. Supports can be simple from a single length of wire or sturdy twine (jute) cord. How about construct a support that mimics a spider’s web.

Annual vines have specific growing needs. For example, sweet pea vines bear clusters of flowers in late spring and early summer (depending on region of the country). Flowers come in a wide choice of colors (red, pink, blue, white and purple), are highly scented, and make excellent cut flowers. Sweet peas stop blooming and vines wither in hot dry weather.

For most vines full sun and an organically rich soil (or potting medium) are perfect. In hot weather climates, provide partial shade in the afternoon. Mature size will depend on plant species; some vines may reach to 15 to 20 feet by autumn. Pinching off the terminal tips will encourage branching. In the first 4 to 6 weeks train the direction of growing shoots with ties. Most vines benefit from monthly feeding with a water soluble fertilizer such as Miracle-Gro™, Schultz™, Daniels™.

Cup and Saucer Vine, Cathedral Bells (Cobaea scandens)

Hyacinth bean vine (Dolichos lablab)

Hyacinth Bean Vine (Dolichos lablab)

Moon Vine (Ipomoea alba)

Cypress Vine, Hummingbird Vine (Ipomoea quamoclit)

Morning Glory (Ipomoea tricolor)

Sweet Pea Vine (Lathyrus odoratus)

Spanish flag, exotic love vine (Mina lobata)

Scarlet Runner Vine (Phaseolus coccinea)

Black-eyed Susan Vine (Thunbergia elata)

Galax- Popular Mountain Plant For Your Woodland Garden

Posted by Hugh on March 13th, 2017

Galax in Western North Carolina Woods (photo by Bob Hale)

Galax (Galax urceolata) is an under planted perennial wildflower native to the southern Appalachian mountains and eastern U.S. (USDA hardiness zone 5). Galax foliage is frequently collected from the wild for use in the winter floral decorations. Unfortunately, over-harvesting on public lands has jeopardized wild populations.

Galax grows 6 to 12 inches tall and is recognized for its dark evergreen glossy leaves which are round to heart shaped. The glossy round leaves of galax often turn a beautiful burgundy color in winter, particularly if weather is extremely cold and lacking in snowfall.

Galax is sometimes called “wandflower”. In late spring (June in SW Virginia, Western NC and East Tennessee) white flower spikelets emerge through the foliage on leafless stalks or “wands”.
The flower spikes, adorned with tiny white flowers, rise 9-12 inches above the dark glossy green foliage.

Galax grows best in cool, moist, well-drained, mildly acidic woodland soil. Allow galax 2 – 3 years to establish. Vigorous plants will slowly colonize and eventually form a dense carpet in your woodland garden. Long term success is built on soil moisture and not on how much you fertilize it. Mulching with pine needles helps to acidify soils over the years. Do not allow fallen leaves to smother the planting

Galax is a wonderful woodland ground cover and deserves greater landscape use. Deer will occasionally browse planting(s). Mt. Cuba Center in Greenville, Delaware recommends planting with Eastern teaberry (Gaultheria procumbens), Rosebay rhododendron (Rhododendron maximum), Mountain laurel (Kalmia latifolia), bellwort (Uvularia spp.) and crested iris (Iris cristata).

Cool Plant Combos For Containers

Posted by Hugh on March 10th, 2017

Phormium, 'Phantom' etunia and An Aggressive Sweet Potato Vine

Phormium, ‘Phantom’ petunia, and too aggressive Sweet Potato Vine

Mix of Begonia, Calibrachoa, Pennisetum, Bracteantha

As more and more urban gardeners are growing in small spaces, including decks and patio of condos and town houses, container gardens are becoming more significant. They’re creating large mixed containers that include miniature trees and shrubs rather than their big cousins.

For design containers may include thrillers (tall or spiky), fillers, and spillers (weepers). They contain splashes of color or many color contrasts.

Here is a few design ideas that blend shrubs/trees, perennials, and annuals together for great effect:

Container size is of key important. Large, wide (broad base) containers are the best to avoid tipover from high winds. Halved wine barrels or large concrete planters are good choices for a permanent fixture, as their weight ensures that they won’t get blown over easily. Containers must have one or more drainage holes or a 3-4 inch reservoir containing coarse pea gravel.
Use a miniature tree or shrub as the tallest feature in the planter. Include woody landscape trees and shrubs such as: dwarf columnar conifers, Japanese maple (Acer), camellias, buddleia, hydrangeas, or crapemytle (Lagerstroemia).
Use annuals to add bold color(s) to the display. Great selections to handle the summer heat include: begonias, calibrachoas, impatiens, annual vincas (Catharanthus roseus), scaevolas, and Mexican heather (Cuphea hyssopifolia).
Include perennials to fill in spaces and that add their own lovely color and contrast. Some of the best perennials for this role are: coral bells (Heuchera), miniature and small leaved hostas, sedges (Carex), sweet flag (Acorus), monkeygrass (Liriope), and assorted ferns.
Use plants with similar growing conditions, e.g. in partial to full sun or shade or moist or dry potting soil.
Use a mixture of early-, mid-, and late-season blooming plants to ensure a colorful display all season long.
Check plant hardiness of woody plants in your area to add to container.

Growing Tips: woody landscape trees and shrubs and some perennials need to be transplanted every 2-3 years in late winter. Replace the soil (media) and root and shoot old plants before adding new soil (media). Feed with a slow release fertilizer such as Osmocote™, Scotts™, and Nutricote™.

‘Crippsi’ False Cypress, petunia, and dichondra

Autumn Ferns Offer Lush Tropical Touch

Posted by Hugh on March 7th, 2017

Autumn fern in mid-spring

‘Brilliance’ in a June Garden

Ferns are fine textured lacey-leaf groundcovers. Many kinds of ferns add a tropical accent to the shade garden. Autumn fern (Dryopteris erythrosora), aka Japanese wood fern, has evergreen or semi-evergreen arching foliage, depending how cold winter is (USDA hardiness zones 5 to 8).

Its common name is misleading. Best fronds color is in spring; fronds unfurl with a coppery-red tint and gradually fade to medium to dark green after 4-6 weeks. In late summer, bright-red spore clusters (sori) appear on the frond’s underside. In fall, fronds develop more of a russet tone.

Once established, autumn ferns grow happily beneath large shade trees or in dry soils. Initially, start them off with plenty of water, compost, and mulch to get root system established. They prefer an evenly moist soil, and mildly acidic soil pH between 5.5 and 7.0. Established plants are moderately drought tolerant.

In early spring emerging fiddleheads (fronds) unfurl to form a vase-shaped clump, 18-30 inches tall and wide depending on age. Clumps spread slowly by underground roots. At planting, space 16-18 inches apart for dense coverage. Indifferent to heat, humidity, and cold, this moderate shade lover excels in full morning sun in zone 5 and 6, but wants more shade in southerly climes.

From then on, autumn fern performs season after season with little additional care. It has no serious pest or disease problems and soil nutritional needs are minimal. Applying 2-3 inches of leaf mold is almost equivalent to feeding with slow release fertilizer.

The cultivar ‘Brilliance’ grows 2 feet high and wide and offers long seasonal impact. Its frond’s color is exceptional, that is, the upper surface has a deep coppery tint and high gloss, rich green color through most of the summer, and returns to a russet color in autumn.

Enjoy The Double Soft Pink Flowers of Kwanzan Cherry

Posted by Hugh on March 4th, 2017

‘Kwanzan’ Cherry Tree

Soft pink double flowers

Kwanzan cherry (Prunus serrulata ‘Kwanzan’) is a commonly planted Oriental cherry in the U.S. (USDA hardiness zones 5 – 8). It’s most often utilized as a small 25 to 35 foot tall flowering deciduous tree in an open lawn, patio. and deck setting for its cool summer shade. It is a 4-season specimen and should be located where it can be viewed year-round.

Kwanzan cherry is in glorious flower in mid-spring and is frequently planted along with Yoshino Cherry (P. x yedoense) in Washington, D.C. and Macon, Georgia for their annual Cherry Blossom Festivals. Yoshino cherry produces abundant single pale pink cherry blossoms a full week or two before Kwanzan. The later blooming Kwanzan is less prone to late spring frosts, which is so important to festival planners.

The 2-inch diameter powder-puff pink flowers are comprised of 24 – 28 petals, with no sexual floral parts. Therefore tree will rarely produce fruits. Flower clusters of 3-5 blossoms develop at each node. New spring leaves are bronze colored at the start and turn to a medium green within a few days. In autumn leaves turn yellow, orange, or copper colored. A unique way to identify Kwanzan is the pair of large distinctive glands at the base of each leaf blade.

Site selection is very important in growing Kwanzan cherry. It performs best in full sun and in a well-drained fertile soil. Hot, dry summers can shorten a tree’s life span. Annual pruning is absolutely essential and should be performed immediately after flowering. Remove dead, weak, or sickly branches, including those that may be infested with scales and other serious insect pests.

Kwanzan cherries are prone to a long list of insect and disease problems, including cankers, black knot, leaf spot, die back, leaf curl, powdery mildew, root rot and fireblight. Potential insects include aphids, scales, borers, leaf hoppers, caterpillars, tent caterpillars, Japanese beetles and spider mites. Canker, borers and virus can be particularly troublesome under high stress environmental conditions such as hot droughty sites.

Native Red Buckeye Tree Delights in Landscape

Posted by Hugh on March 1st, 2017

Red buckeye at Biltmore Estates, Asheville, NC

Red tubular flowers and palmate foliage

Red buckeye (Aesculus pavia) is a southeastern U. S. native that has become more recognized as a wonderful small landscape tree (USDA hardiness zones 4-8). In its native habitat it is an understory large shrub or small tree frequently surrounded by taller trees or structures. A mature specimen may grow 20-25 feet high and wide in 30 years.

Showy, erect, 4-10 inch long panicles of red to orange-red flowers appear in spring. Many 5- to 9- inch long tubular flowers stand erect on branch tips as decorative candles in late April and May in zone 6. Flowers open at the same time the palmate leaves emerge. Flower tint may vary from dark pink to deep red on individual buckeyes growing next to one another. A rare yellow flower form, listed as A. pavia var. flavescens, is offered by a few specialty plant nurseries. Hummingbirds and butterflies pollinate individual flowers.

Red buckeye grows in average, moist, well-drained soil, and in full morning/afternoon shade or in all-day partial sunlight. The tree holds up to lots of shade although flower numbers are less. Spring feeding with granular 10-10-10 or equivalent fertilizer plus the addition of 2-3 inches of a fresh organic mulch are highly recommended. Soil moisture is of key importance. Summer foliage tends to scorch and declines sooner in dry warm conditions. In southern climes all-afternoon shade is the rule!

Attractive glossy, dark green, palmately compound leaves are attractive in spring and early summer. Disease and pest problems prove to be of little consequence, except that scorched and disease spotted foliage have dropped by September 1st and branches are mostly bare.

Smooth orange-brown seed husks contain 1-3 shiny seeds (1-2 inch long nutlets). Seeds are called “buckeyes” and ripen by early fall. New plants can be grown from seeds. They should be planted immediately and not allow to dry out prior to sowing. Seedlings often flower 3-4 years later. Seeds are poisonous and are rejected by most wildlife.

Getting A Sourwood Tree Going

Posted by Hugh on February 26th, 2017

Wild tree at NC Arboretum in Asheville, NC in October

Young Sourwood Tree

Sourwood (Oxydendrum arboreum) is one of our most beautiful U.S. native trees. Trees often grow multi-stemmed or shrub-like to 20-30 feet or in tree form to 35-40 feet high and narrow in spread. Trying to establish a new tree can be challenging.

In the wild sourwoods are often found growing in shallow soils on steep craggy mountainsides. They are a pioneering species. Tiny dehiscent seeds are dispersed into the wind and blown, like dust, from established trees over many acres of land. Tens of thousands of seedlings may germinate but few may survive. In Tennessee I have seen new seedlings prospering on cleared reclamation sites where soils are poor.

For a home gardener the challenge is to get this finicky species to survive its initial two years. Site them in the type of soil and environmental conditions which rhododendrons and mountain laurels enjoy. Newly-planted sourwoods tend to prioritize by establishing its root system first. New shoot growth may be slow.

Sourwood should be planted in late winter to early spring before leaf out. Plant in a well-drained moderately acidic (5.5 to 6.5 pH) soil. Prune back the new tree to 1 – 2 feet from the ground at planting. Essentially, you are starting over with 100% root system and 10-15% top growth. Within 2 months one or more root suckers may sprout and this will be your new sourwood. Select 1-3 of the most vigorous shhots and eliminate all others. Feed with 10-10-10 or equivalent granular fertilizer and irrigate during long dry periods.

In nature sourwoods seem to prefer the eastern facing slope in an open woodland area where they receive midday sun. Young transplants respond to fertilizing; older well-established trees do not. Sourwoods need some pruning, mostly to develop the tree’s framework. They have few serious insect or disease problems. Purple spotting on leaves is common in early autumn, but causes little injury.

Finding a nursery grown tree for sale is rare and many sellers will not guarantee them. Some on-line nurseries do list them.