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

Light a Candle in Your Garden

Posted by Hugh on May 1st, 2011

'Giles van Hees' veronica

Speedwells (Veronica spp.) are long-blooming, easy-care perennials. Speedwells are outstanding for their color rich floral candles (spikes). The candle-like flowers rise like sentinels in the late spring-summer garden and attract lots of butterflies and bees.

The small individual 5- pedaled blossoms range in colors from white, pink, blue, and several shades of purple. The floral spikes open at the base and continue upward. Cultivar sizes vary, making veronicas a great choice as the front, middle or back border in any flower bed. Personal picks include V. ‘Giles Van Hees’ (6- inch bright pink spikes) and V. ‘Royal Candles’ (15-inch blue-purple spikes).

Speedwells belong in full sun, planted in a moist, well-drained soil. Soggy soils may lead to a root rot and foliar mildew diseases. Summer irrigation and mulching aids to conserve soil moisture and suppress weed competition.

Quick removal of the old flower spikes (deadheading) encourages growth of new basal foliage and almost continuous flowering through the summer months. Pruning back taller cultivars by one-third reduces the need for staking plants. Dividing perennial crowns every 2-3 years in early spring maintains overall plant vigor.

Take Flight With The Unique Dove Tree

Posted by Hugh on April 27th, 2011

Dove tree

Up for a challenge. Dove tree (Davidia involucrata) is a medium-size tree from China. Mature dove trees are 30-40 feet in height and 20-30 feet in width. A young tree exhibits a pyramidal form and forms a rounded canopy at maturity. The coarsely textured 4 – 5 inch circular leaves are bright green with no significant fall color, dropping either pale green to brown.

In early May dove tree in bloom is an awesome sight to behold. All attention is focused on the two uneven white bracts, one 7- inches long and 4- inches wide and a second shorter 4- inches long anf 2- inches wide bract. A slight breeze rustling past the two white bracts creates an illusion of dove wings aflutter, earning such pseudonyms like “handkerchief tree” and “ghost tree”. The true ¾- inch wide dome flowers are insignificant.

Ordinarily, you must wait ten or more years for dove tree to bloom the first time (and not every year). ‘Sonoma’ is a new cultivar which flowers reliably within 2 – 3 years after planting and does so annually. As the tree ages, its scaly orange- brown bark offers minor winter interest.

Dove tree need to be properly sited in a moist well-drained loamy soil in the Southern Appalachian region (USDA hardiness zones 6 and 7). Guard against extreme summer heat and winter cold blasts and irrigate during summer dry spells. Disease and pest problems are as rare as dove trees.

Dove tree may be purchased from specialty plant nurseries on the internet or from mail order.

Enjoy a Mite-free Alberta Spruce This Summer

Posted by Hugh on April 23rd, 2011

Mite free Alberta Spruce

A popular saying among gardeners is “the right plant in the right location”. They must be thinking of Alberta Spruce (Picea glauca ‘Conica’). Within a few years after planting, this popular dwarf conifer becomes devastated by spider mite infestations. The rule is to plant Alberta spruce where it receives good air circulation on all sides.

A common mistake is to plant Alberta spruce close to a building foundation. Here, the needle foliage on the backside of the shrub facing a wall or foundation remains wet. Often, the bottom one-third of the plant is covered with morning dew after a rain or from overhead irrigation.

Initial mite feeding damage frequently starts on the sheltered, warmer side of the shrub. Repeated mite infestations lead to localized stem and needle death which causes Alberta spruce to look unsightly. Similar symptoms are observed in other shrub species, including junipers (Juniperus spp.), hollies (Ilex spp.), and hemlock (Tsuga spp.).

A backup plan is to spray susceptible shrubs with a timely pesticide (miticide). A timely coarse pressure spray of tap water in early spring and again in early fall will wash most eriophyid and spruce spider mites off the foliage.

* Thanks to Dr. Donald Booth, Research Entomologist at the Bartlett Tree Laboratory in Charlotte, NC for his assistance.

Wolfeyes Chinese Dogwood

Posted by Hugh on April 20th, 2011

Chinese dogwood (Cornus kousa), a favored spring-flowering tree, reaches 20-25 feet in height and blooms two weeks subsequent to our native flowering dogwood (C. florida). The ‘Wolf Eyes’ cultivar forms a compact tree or large shrub, standing 8–10 feet tall and nearly twice as wide. lowly reaches 10 to 20 ft. tall and wide; largest in ideal conditions. (USDA Hardiness zones 5-8).

Wolf Eyes displays an awesome leaf variegation which makes it a focal point in any garden or patio container. Its wide white wavy leaf margin is prominently edged on its olive-green foliage. Leaf variegation is very stable, rarely reverting to all green. Summer foliage is also burn or scorch resistant, best was planted in partial sun in Showy, creamy white flower-like bracts are followed by bright red ornamental fruit.

The off-white four-pointed bracted flowers contribute very little, the small bracts muted by a standout variegated foliage. The green raspberry-like fruit size up and ripen reddish orange color beginning in late summer, attracting lots of famished birds to your property. Showy, creamy white flower-like bracts are followed by bright red ornamental fruit.

Chinese (kousa) dogwood prefers a deep, well-drained, slightly acidic soil. While moderately drought tolerant, mulching and summer irrigation during prolonged dry periods is encouraged. Kousa dogwood is highly disease resistant.

Gordlinia- Nothing Like it Before!

Posted by Hugh on April 17th, 2011

(x Gordlinia grandiflora 'Sweet Tea')

‘Sweet Tea’ resulted from crossing franklinia (F. alatamaha) and loblolly bay or gordonia (G. lasianthus). Sweet Tea is still abit finicky like franklinia, but is more resistant to Phytophthora disease (soil pathogen). This new intergeneric cross possesses huge (5 inch diameter), showy flowers that look like big fried eggs. Sweet tea exhibits semi-evergreen foliage with large, single, camellia-like flowers from July through September.

Why name it ‘Sweet Tea’? It’s a member of the tea family (Theaceae). The flowers have a light sweet fragrance. Both parent species originate from the South where sweet tea runs in our veins. Sweet tea must be planted a good well-drained soil with even moisture year-round. It grows best in full sun or a little afternoon shade. Irrigation during summer dry spells is a must. Roots readily from stem cuttings, then takes off growing. Mature height is estimated to be 20-30 feet. Winter hardiness is likely in USDA zones 7 thru 10. The plant is not patented or trademarked.

Photo credit and article info. from Dr. Tom Ranney, NCSU Plant Breeder, Mountain Crops Research and Extension Center, Fletcher, NC.

Three Mid-sized Ornamental Grasses for Small Gardens

Posted by Hugh on April 14th, 2011

Calamogrostis 'Karl Foerster'

For their sheer architecture alone, ornamental grasses provide 4- seasons of landscape excitement. Within a small garden space three mid-sized (4 – 6 feet tall) ornamental grasses with awesome vertical stature excel. All are highly rated for long garden life and low annual maintenance.

‘Karl Foerster’ Feather Reed Grass (Calamagrostis x acutiflora ) forms silvery bronze inflorescences (plumes) in mid- summer above its green foliage. The feathery inflorescences start out creamy white with a pinkish tinge. Against brisk winter winds the narrow golden straw plumes stand tall. Seed heads are sterile and not invasive.

‘Morning Light’ Eualia grass (Miscanthus sinensis) has very narrow green leaf blades with a well-defined white midrib line. Pinkish brown plumes appear in mid to late August and stand 12 – 18 inches above the soft textured foliage. Morning Light is not invasive as some Miscanthus species as the seed heads are mostly infertile.

‘Northwind’ Switchgrass (Panicum virgatum) exhibits the tightest vertical form of any switchgrass cultivar. Northwind‘s blue-green foliage is wide and its attractive pink to reddish plumes appear in early September. Northwind grows 4 – 5 feet tall and a narrow 2 – 3 feet wide. Plants remain tall and erect throughout the winter. Switchgrass is a North American prairie species.

All three grasses adapt to a variety of soils, sand, silt or clay loam, and prefer an open area in full to partial sun. Once established, they tolerate dry slopes and boggy areas for a short time. All three grasses may be planted as single specimens or group several planted en mass. Medium sized grasses serve as rear accents or backdrops for smaller plants in front. They grow equally well in containers either alone or mixed among other perennials.

Plant them near water gardens or along stream banks and at the edge of a pond. In coastal areas, Panicum and Miscanthus grasses tolerate salt spray. Foliage and flowers of ornamental grasses are effective in fresh and dried flower arrangements.

In early spring lop them back to within 6 – 8 inches above the plant crown. Grasses are best divided as clumps begin signs of life.

A Perfect Small Garden Tree– ‘Ace of Hearts’ Redbud

Posted by Hugh on April 11th, 2011

'Ace of Hearts' redbud

'Ace of Hearts' summer foliage

Ace of Hearts redbud (Cercis canadensis ‘Ace of Hearts’) is an arboreal treasure, a compact form of our native redbud. Heavy clusters of light purple pea-like flowers cover twigs and branches from late March into early April, depending on your locality. Ace of Hearts grows 12 by 15 feet in height and spread, roughly one-third smaller than standard seedling redbuds. It makes an ideal fit in small and suburban gardens.

Its small semi-glossy heart-shaped leaves are less than half the size of other redbuds. Leaves are spaced close together, each one overlapping another like shingles on a roof. Its dark green summer foliage turns yellow in autumn before falling. Few, if any, unsightly seed pods are produced.

The overall tree holds its dense dome- shaped canopy over several years. Established (2 years planted) trees are exceptionally heat and drought tolerant. Ace of Hearts is susceptible to very few serious disease and insect problems.

Grow this redbud in any well-drained garden soil in full or partial sun, providing a minimum of 6 hours of sunlight to insure good flowering. This compact grower requires very little annual pruning, which is best performed after flowering.

Double Take™ Flowering Quinces

Posted by Hugh on April 8th, 2011

‘Scarlet Storm’ Flowering Quince

Photo credit: Dr. Tom Ranney, NCSU Research Horticulturist

Flowering quince (Chaenomeles spp) is an early spring flowering shrub, treasured for its brightly colored blooms (USDA hardiness zones 5-9). Old fashioned quince shrubs produced small amounts of fruits which were gathered and prepared into yummy jelly in the autumn kitchen. These often large 10-12 foot tall shrubs produced small sharp thorns which made picking the fruit a challenge.

Now appearing in a garden center near you are three new compact quince cultivars: ‘Orange Storm’, ‘Scarlet Storm’ and ‘Pink Storm’. Dr. Tom Ranney and his team at the Mountain Crops Research & Extension Center near Asheville, North Carolina developed the three “Storm” quinces, marketed as the Double Take™ series. Plants grow 3-4 feet in height and average 4-5 feet in width.

The big, vibrant colored, double flowers provide a stunning early spring display. The camellia-like blossoms measure 1 ½ – 2 inches across and open in early spring before the leaves. Flowering branches make good cut displays. Once quinces become established after two years, shrubs are very drought tolerant. Branches are thornless and deer resistant. Double- flowered quinces do not produce fruit and are easy to care for.

After flowering, quinces may be pruned as specimen shrubs, espaliers or hedges. Feed with a slow release fertilizer such a Osmocote™ or Nutrikote™ in late winter.

Wild Onion or Wild Garlic?

Posted by Hugh on April 5th, 2011

Wild Garlic weed patch

Often called “wild onion”, many gardens (including mine) from late winter into spring in eastern Tennessee, western NC and southwest VA are instead plagued by wild garlic (Allium vineale).

Wild garlic forms a rounded blade (stem) while wild onion (A. canadense) has a flattened blade. When freshly cut, the hollow stem of wild garlic is easily visible. Both lawn weeds are edible in a chemical-free lawn and garden. However, chemical herbicides may be your primary option to eliminating both of these noxious weed pests.

Wild garlic forms patches of perennial bulblets which multiply and return each year in greater numbers. Hand pulling is rarely a viable option because the bulblet root system breaks off and sends up a new plant, often within a week. You need to dig and lift beneath the bulbs.

Frequent mowing cuts off flowers to prevent seed head formation. Maintaining a dense stand of lawn grass crowds out wild garlic (and other weeds).

Effective chemical herbicide products include: 2,4-D, Dicamba, Clopyralid, and Triclopyr. Combination herbicides containing two or more of the above products are most effective. Adding a few drops of a spreader/sticker provides better herbicidal action.

This post-emergent treatment also controls white clover, dandelions, ground ivy, thistles, chickweeds, henbits, red sorrel, and wild violets.

No Excuse for Tree Topping

Posted by Hugh on April 1st, 2011

Maple tree "hat rack"

Why do people top trees? Often, it is because “their neighbor(s) did it”. When asked whether they believe their neighbor to be a wise person, the typical response is “NO”.

The Negatives About Tree Topping: 1. A topped tree reduces property values in a community. Topping adds a blight look to a neighborhood or over an entire city; 2. A topped tree is more threatening. Re-growth branches are weak and dangerous to park cars, people, and particularly children playing beneath them; 3. A topped tree costs you more in future expenses; and 4. The tree may not survive topping.

If you feel threatened by a large tree, either have the tree pruned by a certified tree arborist or remove the tree. Select a new replacement tree based on its height at maturity. A properly pruned tree has limbs cutback to their point of attachment to a larger branch or trunk.

What’s wrong with tree topping:

Removal of too much tree top reduces numbers of leaves, starving tree roots
Opening tree center causes sunscald, injuring bark and burning wood which leads to disease
Large pruning cuts don’t heal, causing tree infections
New growths are weak and snap off in wind and ice storms making tree more hazardous
Disfigures the overall look of the tree