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

Less Invasive Rose Of Sharons (Altheas)

Posted by Hugh on April 12th, 2015

‘Purple Chiffon’ Althea

‘Diane’ althea

In several states rose of Sharon or altheas (Hibiscus syriacus) are classified as exotic (non-native) invasive shrubs (USDA hardiness zones 5-8). Their seedlings are invading U.S. woodlands. Plant breeders are now developing less invasive cultivars.

The double-flowered altheas produce far fewer fertile seeds; stamens and pollen sacs are mostly embedded within the flower petals. Azurri Blue Satin® is a new seedless form with celestial blue blooms. Sugar Tip® althea is covered with light pink and white double frilly petal blooms; Sugar Tip’s variegated foliage is green with creamy white edges. Both cultivars grow 8-12 feet tall and 4-6 feet wide.

Most double-flowered altheas produce some fertile flowers and are much preferred over open single invasive forms. Among the best are Blue Bird (dark blue double), Blushing Bride (multi-pink shades double), Freedom (purplish-pink), and four cultivars in the Chiffon series (Blue, Lavender, Pink and White).

Over a quarter century ago, the U.S. National Arboretum released four tetraploid cultivars, called the Roman Goddess series. Diana (white), Aphrodite (rose), Helene (white/purple), and Minerva (lavender) are seedless forms.

Altheas grow best in full sun and in average, well-drained, pH neutral soil. Altheas are utilized as single specimen shrubs, or grouped together for hedging, privacy screening or border plantings. They attract butterflies and hummingbirds, plus deer generally leave altheas alone. Prune as needed to size and shape from late fall thru winter. Altheas bloom on current season growth. Apply a slow release fertilizer such as Osmocote™ and Nutrikote™ in early spring as new growth begins to emerge.

‘Sugar Tip’ althea with variegated foliage

Ground Nesting Bees Are Beneficial Pollinators

Posted by Hugh on April 10th, 2015

Ground Bee photo provided by Dr. Frank Hale, Entomologist at the University of Tennessee

Spring signals the return of many species of birds and the bees to yards and gardens. In early spring increased activity by ground nesting bees cause alarm for many people; dirt pile nests start appearing in bare patches in the lawn. They are beneficial pollinators in the garden.

Bees in the families Colletidae and Andrenidae represent the ground nesting solitary bees. They do not form hives. Solitary bees spend much of the life in the pupa stage in shallow underground tunnels or galleries; the queens live individually and raise their young. Ideal location for the nests are warm sunny grassless patches in well-drained soil; the ground should warm up quickly in the morning.

Nest or mound entrances are only a few inches across. Nests (holes) improve soil aeration holes that help in the downward movement of water and nutrients. Each spring ground bees abandon old nests, mate and build new ones. Many females may nest in the same area.

Ground bees pose little or no threat to people. Male bees comprise the majority of above-ground swarmers, and do not have a stinger. The mostly subterranean queens do have stingers, but rarely defend their nesting area. They are very docile and not likely to sting. However, if you are stung, persons with extreme sensitivity should always carry an Epipen to protect against an allergic reaction.

Ground bees are highly beneficial to your lawn and garden. To be rid of ground bees, you do not need to use pesticides. Lots of ground activity, from frequent tillage, mowing, or irrigation, will destroy nests. Simply watering the area will cause bees to move to another area.

Million Bells (Calibrachoa)

Posted by Hugh on April 8th, 2015

Calibrachoa ‘Liberty Hot Pink’

Calibrachoa ‘Double Amethyst’ container

Among gardeners “million bells” or “callies” are common names for calibrachoas (Calibrachoa x), spring-summer-fall flowering annuals; they’re closely relative of petunias (Petunia spp.). Low spreading plants are blanketed with small petunia-like flowers from spring until frost. Blooms hold up well to rain showers and do not need to be deadheaded. Plants are heat-tolerant and disease resistant.

Grow calibrachoas as you would petunias; they excel in containers and hanging baskets. Calibrachoas measure 6 to 12 inches high and 24 to 48 inches spread. Showy flower colors range from lavender, blue, red, pink, salmon, orange, yellow, white; blooms attract hummingbirds, butterflies and bees.

Calibrachoas grow best in full sunlight. In the deep south, a site that favors morning sun and afternoon shade is preferred. After the threat of spring frost has subsided, plant them in containers filled with a well-drained organic-based potting mix. Space plants 12 to 16 inches apart. If grown in garden beds, a moderately acidic soil is best; mid-summer leaf yellowing is a symptom of a high pH or alkaline soil.After planting add 2-3 inches of mulch. Overwatering or a poorly drained soil is the death knell of calibrachoas.

Supplement with a slow release fertilizer such as Osmocote™ or Nutricote™ according to package directions. Calibrachoas in containers may be nurtured with a water-soluble acidic fertilizer such as Miracle-Gro™, Schultz™, Daniels™ biweekly.

Aphids can become major pests on new growth. Freshen plants with a late summer shearing using a scissors or pruning shears. Clipping encourages renewed growth and flowering. Calibrachoas are very cold tolerant and usually survive into late autumn season.

Superbells, Minifamous, Alhoas, and Callies are popular series of calibrachoas.

‘Blizzard’ Pearlbush Is Superior Choice

Posted by Hugh on April 5th, 2015

‘Blizzard’ Pearlbush (photo courtesy of Dr. Tom Ranney)

Large flowered ‘Blizzard’ pearlbush

Once upon a time pearlbush (Exochorda spp.) was a popular old-fashioned spring flowering shrub. Its flurry of white flowers followed forsythia in early spring bloom cycle (USDA hardiness zones 4 to 8, excel in 7 & 8). New on the garden scene is ‘Blizzard’ (E. x Snow Day™) pearlbush. It is blanketed with large white 5- petalled flowers, twice as large as other varieties of pearlbush.

Blizzard pearlbush is an interspecific hybrid (tetraploid) of three Exochorda species and is the creation from Dr. Tom Ranney, plant breeder at the Mountain Crops Research And Extension Center in Fletcher, NC. This 5-6 feet shrub gem displays a distinctive upright branching form compared to taller and rankier varieties. Blizzard pearlbush needs little pruning to maintain its compact nature and may be trained into a diminutive tree. Pruning is best done in spring after flowering is over.

Pearlbush grows in any average soil that is well-drained and mildly acidic. Feed with a slow release fertilizer in late winter such as Osmocote™ or Nutrikote™. Early-spring branches are ideal for forcing inside your home. Pearlbush is highly disease and pest resistant. Spring-summer foliage is medium green and fall changeover is blah.

Pearlbush is native to China. For a great visual look in the spring landscape, set out multiples of Blizzard pearlbushes 5-6 feet apart to develop a short privacy screen or border.

Shop early as the availability of new Blizzard pearlbush may be limited at local garden centers this spring (under the Proven Winners (PW) logo).

‘Cherokee Brave’– Outstanding “Red” Flowering Dogwood

Posted by Hugh on April 3rd, 2015

Cornus florida ‘Cherokee Brave’

Flowering dogwood (Cornus florida) is the most beautiful of U.S. native flowering trees (USDA hardiness zones 5 to 9). It typically grows 15-30 feet tall, but larger forms are known. The tree is broadly-pyramidal at a young age, branching is low, and matures with a rounded canopy. Spring bloom time usually overlaps with redbud (Cercis canadensis) which are finishing up. In 99.99% of the time, seedling dogwoods produce four petal-like white bracted flowers that measure 3-4 inches across.

‘Cherokee Brave’ produces dark pink bracts. Many texts describe the flowers as “dark red”. Pink color tones may not be as vivid if the spring weather is unseasonably hot or the tree is growing in warm southern climes. Cherokee Brave is a vigorous grower and bears flowers at an early age. The oval shaped leaves, 3-6 inch long, emerge with a slight reddish tint, and mature dark green by late spring. Foliage takes on intense shades of red, burgundy and purple in autumn before abscising.

Flowering dogwood is a popular small spring flowering tree in the northeast and mid-South regions of the U.S. Troubles with two fungus diseases, anthracnose and powdery mildew, has caused it to fall out of favor. Cherokee Brave exhibits above average resistance to both diseases, particularly the latter. Flowering dogwood is utilized as a specimen or small grouping on residential, parks, and commercial properties.

Plant flowering dogwood in an average well-drained soil and in full sun to part shade. For long life, it prefers a moist, organically rich, acidic soil in partial sun. The tree benefits from 2 – 4 inches of mulch to keep tree roots cool and moist during the summer. Following a 2- year establishment timeline, flowering dogwood exhibits good drought resistance.

Flowering dogwood’s brightly red drupe fruits are relished by birds and 4-legged creatures in the forest including deer. Their flowers attract numerous early arriving springtime butterflies. Its rugged alligator hide bark and branching silhouette are special winter features.

Building A Wildlife Wall In Your Garden

Posted by Hugh on April 1st, 2015

Wildlife Wall in Bristol, TN Garden

Many beneficial garden insects, such as ladybugs and ground beetles, struggle to find habitats in our manicured gardens. Consider creating an attractive wildlife wall to lure them in. Keep them happy and they will help reduce harmful pest populations.

Dr. Douglas Tallamy, through his thoughtful book “Inviting Nature In” and other writings, have spurred gardeners to invite more beneficial critters into their gardens. One fascinating project is to build a wildlife wall. It is a very simple task to put one together. No two may look alike, so add your own creativity.

A wildlife wall is a shelter full of all kinds of holes and crevices so that any creature (toads, spiders, and any other insects) that needs a hiding place that wants to can move in. Within a short time you may observe mason bees, ants, even a tree frog. Some of nature’s beneficials such as snakes, wasps and hornets will come, but may not be welcome.

Suggested Materials:

Sedum, Sempervivum, or Delasperma plants
cinder blocks and/or bricks (with holes in them)
small blocks of wood, drilled with different sized holes
roof or drainage tiles
sheets of plywood or planks of wood; old wooden pallets
straw, corrugated cardboard, slate chippings, various diameters of bamboo, clumps of moss, twigs
soil and/or sand

Select a quiet (less frequented) area of the garden and establish the base using cinder blocks, bricks, and/or tiles. Leave plenty of gaps where critters will find shelter and move in. Use roof tiles to keep excess moisture out.

Solitary bees may make homes in the bamboo cane holes. Ladybird beetles will create laying sites in rolled up corrugated cardboard. Create a living roof by planting with iceplants, sedums, sempervivums, and other arid-loving plants which attract numerous pollinators.

Once friendly critter inhabitants have moved in, your wildlife wall requires no attention. Expect some organic parts (wood, straw, moss, etc.) to decay over time and need some repair. Straw may be taken away by nest-building birds elsewhere.

The Forsythia Revolution

Posted by Hugh on March 29th, 2015

Standard size forsythia (Forsythia x intermedia)

Forsythia ‘Gold Tide’

In most areas of the U.S., the golden yellow blossoms of forsythia (Forsythia x intermedia) signals that worst of winter weather is almost over (USDA hardiness zones 4 to 8). Over 2-3 weeks bright yellow flowers cover this easy to grow shrub. Priced at under $20, a good-sized forsythia shrub is a bargain, often used to lure customers into the door.

Forsythias are small to medium-sized ornamental shrubs maturing between 4 to 10 feet tall by 5 to 12 feet wide depending on cultivar. It has an upright oval, open, growth habit with long arching growth habit. The shrub can easily take on a straggly appearance unless pruned every 1-2 years. Dwarf and semi-dwarf cultivars are available; the most popular form is Gold Tide™ at 3 to 4 feet tall and 5 to 6 feet wide.

Other popular cultivars include:
‘Sunrise’- compact 5 feet tall habit
‘Golden Nugget’ – grows to 5 feet tall and wide
’Spring Glory’ – 6 to 7 feet tall with pale yellow flowers and an upright habit.
‘Lynwood Gold’ – popular old fashioned cultivar with bright yellow blooms
‘Northern Sun’ – floral buds are hardy to -30°F.

Forsythia is best grown in full to partial sunlight (minimum 6 hours sun for best flowering). The shrub flowers less and branches grow tall and lanky in partial shade. It prefers moist, well-drained soils but adapts to poor soils, is not pH sensitive, and is very drought tolerant. It is rarely troubled by disease or pest troubles.

Vigorous growing forsythias are best pruned within 2-3 months after spring flowering. Most attention should be directed to remove thick (oldest) wood; this greatly will reduce the height of the shrub. Also remove weak basal suckers less than pencil thickness. Flower buds are set in mid- to late-summer. Late summer pruning should be avoided.

The 3 – 4 inch long medium green leaves turn an unexciting off-green, yellow, and purple in autumn before abscising. The olive to yellow-brown wood is covered with raised lenticels. Floral buds are evident by early fall and a few often flower during warm autumn days.

Forsythia is utilized as a specimen shrub or en masse as a deciduous hedge or intermediate privacy screen.

Fruit Gardening In Containers

Posted by Hugh on March 26th, 2015

Great packaging along with exciting breeding has ignited interest in growing small fruits in containers. In recent years the BrazelBerries^™ fruits have become popular at garden centers.

Brazelberries is the creation of the Brazelton family of Fall Creek Farm & Nursery, Inc. in Oregon, who have been propagating and growing berry plants since the 1970’s. Their breeding program is focused on offering tasty and beautiful berry plants for containers and gardens. Fruits are easy to grow and are both delicious and nutritious to eat.

Easy care BrazelBerries make attractive landscape plants in a sunny garden spot as well as in decorative patio and deck containers.

Plants are compact in size and can be grown in #3 or #5 nursery containers or in larger ceramic urns.
Great tasting for your guests snacking or as appetizers at a summer garden party. Try Peach Sorbet® blueberries, Jelly Bean® blueberries, or Raspberry Shortcake® raspberries.
Mix with small shrubs, perennials and annuals along a pathway or group several together for ornamental beauty.
Create an edible landscape whether for snacking or as a wildlife attraction.
Clip of fruiting branches to utilize in floral arrangements.

To maximize fruit production, fertilize with Miracle Gro™ or Peters™ every 2-3 weeks during the growing season and prune plants in late winter before new spring growth begins. Fruit plants are disease resistant but may have occasional problems with aphids.

Better Disease Resistance With Mountain Tomato Series

Posted by Hugh on March 24th, 2015

'Mountain Pride' Tomato (Photoprovided by Dr. Randy Gardner)

‘Mountain Pride’ Tomato (Photo credit: Dr. Randy Gardner, retired NCSU Plant Breeder)

Tomatoes are attacked by several diseases and insects. Most serious diseases are early blight, spotted wilt virus (TSWV), fusarium wilt (FW), Stemphylium Gray Leaf Spot (St), Alternaria leaf spot (A), and root knot nematodes (N).

Major insect problems are aphids, thrips, stink bugs, blister beetles, fruit worms, horn worms, leaf miners, fruit flies, and white flies.

Some problems are nutritionally- or environmentally-caused including blossom end rot (low soil calcium, lack of soil moisture), fruit cracking (excess water and high temperatures), sudden wilting (root damage from cultivation or drowning), blossom drop (drastic temperature changes, poor nutrition), and sunscald to fruit (loss of foliage from disease).

The most impressive series of disease resistant tomato varieties has come from the breeding program of Dr. Randy Gardner at the Mountain Crops Research Station in Western North Carolina. Over a past twenty years, he has released over a dozen very productive, great tasting tomato varieties starting with Mountain Pride. Here are nine in the series:

Mountain Pride – crack resistant large red fruits; VFFASt resistant
Mountain True – indeterminate late blight, resistant to early blight and fruit cracking; sweet tasting 2 oz. campari tomato
Mountain Fresh – determinate, late producing; large 10 oz. fruits with red skin and red flesh color; VFFN resistant
Mountain Majesty – large 3 ½ inch crimson fruit; FW, VW, and TSWV resistant
Mountain Glory – high yielding 12 oz. red globe shaped fruits; VFF and TSWV resistant
Mountain Spring – determinate, bush-type tomato; large 9 oz. fruits; VF resistant
Mountain Magic – indeterminate, highly disease resistant; 2 oz. fruits; VF resistant
Mountain Supreme – determinate, mid-season, red globe; VF, early blight resistant
Mountain Belle – high yielding small bright red cherry tomatoes; crack resistant

Code Symbols meaning:
V Verticillium wilt
F Fusarium wilt
FF Fusarium, races 1 and 2

New Redbuds With Striking Foliage Abound

Posted by Hugh on March 21st, 2015

New Ruby Falls’ redbud

New ‘Rising Sun’ redbud

Over the past decade Eastern redbud (Cercis canadensis) has undergone a real facelift. This native spring flowering tree can no longer be solely identified by its green heart-shaped leaves. New foliage color choices will decidedly catch your eye and win you over. With some reservations most redbud cultivars fall within USDA hardiness zones 5-9.

Purple-leaf ‘Forest Pansy’ redbud, released over 70 years ago, continues to be very popular. Today, two gold-colored foliage cultivars, ‘Rising Sun’ and ‘Hearts of Gold’, are catching on with landscapers. The dark yellow tint holds all spring and summer long. Brand new Solar Eclipse™ flaunts striking peach-orange foliage.

In the white variegated leaf category is new Alley Cat™, selected by Allen Bush of Jelitto Seed. The variegated foliage does not burn or fade like old-timey cultivar ‘Silver Cloud’. Floating Clouds™, a new Don Shadow introduction, boasts green foliage generously splashed in white; it does not scorch in the summer sun.

Gardeners with limited space may opt for low weeping redbud forms. Old-timers like ‘Covey’ (Lavender Twist®) and ‘Traveller’ continue to be popular green leaf weepers. New weepers include Ruby Falls™ and Whitewater™. Ruby Falls is essentially a weeping ‘Forest Pansy’ with striking white and green variegated spring foliage. Whitewater is a tree weeper with green leaves sprinkled with white flecks.