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

Tips On Planting Landscape Trees or Shrubs

Posted by Hugh on April 18th, 2017

Newly planted tree (note use of too much mulch)

newly set shrubs

For some senior gardeners, planting a tree or shrub in your landscape may be a difficult task. The loss of a newly planted tree may be expensive as well as heartbreaking. Following proper planting techniques should avoid any mistakes.

Here are a few tips to make the job a lot easier. No need to dig deep holes…. shallow wide holes are better. Planting hole is the same depth as plant grew in the nursery. Avoid planting trees and shrubs too deeply.

Dig the hole three times wider than the root ball. Plant the tree green side up in the hole and back fill with the original soil removed from the hole. The uppermost topsoil should be placed back into the bottom of the hole.

What to plant? Select the desired plant hardy in your area. Determine the plant zone where you live on-line. Plant zone information is listed on the plant tag. Never assume that the local garden center is selling only plants that are hardy in your region. This is not always the case. Know your heat zone rating, soil type and drainage. You also may need to irrigate certain times of the year.

With balled and burlapped (B&B) shrubs and trees, remove wire baskets and twine. Leave trunk wrap on if tree is planted in fall, and remove by summer of the following year. With container grown trees, untangle masses of roots before setting in the planting hole. Don’t buy tightly root bound container plants.

Bare-root trees should be planted in late winter to early spring before they begin to leaf out. Soak the container in water for 8-24 hours and spread out roots prior to planting. Remove circling roots that may girdle the tree many years from now.

Mulch newly planted trees – apply 3-4 inches of an organic mulch and keep it away from the trunk. Bark or wood chips and pine needles are good choices, and new sawdust or wood shavings are a huge mistake as these materials rob the soil of nitrogen.

Watering in your new tree is the last and most important step. A two inch caliper tree may require 5-7 gallons of water. If there is no rainfall after one week, repeat this step. You may need to water again over long dry spells lasting 10 days or more. Your tree(s) should be well established after one year.

ACS SOUTHEAST REGION CONIFER REFERENCE GARDENS*

Posted by Hugh on April 15th, 2017

Taxodium ‘Cascade Falls’

Conifer mix on a property in Waynesboro, VA

I hear people say that conifers won’t grow in the southeastern U.S. Wanta bet!

2016 marks the 8th year of the Reference Garden program sponsored by the American Confer Society (ACS)- Southeast Region. From Kentucky and Virginia south to Florida, 19 public gardens were now participating in the program. Two of the latest additions are Brookgreen Gardens (Murrells Inlet, SC) and Lockerly Arboretum (Milledgeville, GA).

Since 2009, ACS Southeast Region has awarded 21 grants totaling more than $30,000 to the Reference Gardens. The program is funded by the proceeds from regional meetings and auctions. To join the Reference Garden program, a garden must meet certain criteria and agree to submit a short report annually summarizing their conifer related activities.

Despite record heat, drought and excessive rainfall in many areas of the Southeast, Reference Gardens report that more than 600 conifers were planted and a myriad of programs were presented. The ACS Southeast Region Reference Gardens program is helping to spread the word that conifers are a great landscape option in Southern gardens. Here is the latest list of participating gardens:

Gardens of the Big Bend, Quincy, FL

Atlanta Botanical Garden, Atlanta, GA

Armstrong State University Arboretum Conifer Garden, Savannah, GA

Lockerly Arboretum, Milledgeville, GA

Smith-Gilbert Gardens, Kennesaw, GA

The State Botanical Garden of Georgia, Athens, GA

Baker Arboretum, Bowling Green, KY

JC Raulston Arboretum, Raleigh, NC

Brookgreen Gardens, Murrells Inlet, SC

Hatcher Garden-Woodland Preserve, Spartanburg, SC

Moore Farms Botanical Garden, Lake City, SC

East Tennessee State University Arboretum, Johnson City, TN

Memphis Botanic Garden, Memphis, TN

University of Tennessee Gardens, Knoxville, TN

West Tennessee Research and Education Center Gardens, Univ. of TN Jackson, Jackson, TN

Al Gardner Memorial Conifer Garden, Reynolds Community College, Goochland, VA

Lewis Ginter Botanical Garden, Richmond, VA

Norfolk Botanical Garden, Norfolk, VA

State Arboretum of Virginia, Boyce, VA

*excerpted from report appearing in March 2017 ACS Newsletter by Barbie Colvin, SE Reference Garden Committee Chair.

Virginia Sweetspire — A Standout Native Shrub

Posted by Hugh on April 12th, 2017

Virginia sweetspire in May Garden

Fall leaf color of Virginia sweetspire

Virginia sweetspire (Itea virginica) is a native shrub that touts showy white raceme flowers in late spring and brilliant reddish purple foliage in fall (USDA hardiness zones 5-9). Flowers are very fragrant and attracts hundreds of bees and other pollinators.

VA sweetspire excels in moist, humus-rich, mildly acidic soils (pH 5.2-6.5). In its native habitat, this rambling shrub is found growing adjacent to brooks and streams in woodland areas alongside other wildflowers and ferns.

For maximum flowering and intense fall leaf color, grow VA sweetspire in full sunlight and moist soil. It tolerates moderate shade and thrives in average soils. Mulch the ground around the shrub with 3 inches of pine straw, chips, nuggets or other organic material. Once established, usually after one year, this shrub is moderately drought tolerant. Fertilize in spring with a slow release organic fertilizer such as Osmocote™ or Nutrikote™ following package directions.

Hold off pruning until after flowering. Hold this suckering plant to its place and remove old spent flowers to maintain a tidy appearance. Insects and diseases rarely trouble VA sweetspire. If you notice spotting on the leaves, they will likely be harmless. Remove unwanted suckers any time of year. One or two may be dug up and replanted in another location. If suckers are left in place, VA sweetspire will form a wide colony.

Mature plant size is 3 to 6 feet tall and wide, depending on the cultivar. ‘Henry’s Garnet’ is the best-known and is widely grown cultivar at 5-6 feet high and 4-6 feet wide. It thrives in summer heat and winter cold and exhibits excellent flowering and fall color. Put your nose up close to pick up the delightful fragrance. Shorter growing ‘Little Henry’ is 4 – 5 feet tall. ‘Merlot’ grows 4 – 4 ½ feet tall with a deep-red fall leaf color. ‘Saturnalia’ is more upright branched with a standout fall color.

Sweet Potato Vines

Posted by Hugh on April 9th, 2017

Sweet Caroline ‘Light Green’ Sweet Potato Vine at NC Arboretum, Asheville, NC

Illusion ‘Midnight Lace’

Ornamental sweet potato vines (Ipomoea batatas) have been around since the late 1980’s, but their popularity have soared over the past decade. These sweet potatoes aren’t for the table. The colorful vines thrive in the intense heat of U.S. summers from May through September (zones 5-11).

These easily grown plants work well as a low-growing bedding plant, summer ground cover, weepers in hanging baskets and large containers, or vertically climb with trellis support. Older varieties, like Margarita and Blackie, were almost too vigorous and new introductions come in more color choices and grow more compact. Ornamental sweet potato cuttings will root effortlessly in water or soil.

Colorful foliage

Their colorful foliage is the big show. Ornamental sweet potatoes generally do not flower under normal garden conditions. Small, lavender, trumpet-shaped flowers may form in late summer or fall and are mostly hidden under the foliage.

Ornamental sweet potatoes do best and are most colorful in locations that receive 6 hours or more of direct sunlight. They do grow in shadier locations, but vines are not as vigorous or colorful. Average garden soil, fertility and lots of water is all they need.

Insects to watch for

Sweet potato vine is relatively carefree, there are a few problems to watch out for. Pest problems include the sweet potato looper, a caterpillar that chews holes in the leaves, and the sweet potato whitefly.

Control the looper with occasional applications of an insecticide containing BT, spinosad, a pyrethroid (permethrin, bifenthrin, cyfluthrin and others) or carbaryl (Sevin). Wwhitefly can be managed with Summer Light Oil Spray, bifenthrin (Talstar™or Malathion. Disease issues are minimal.

Newer cultivars

New cultivars display various leaf shapes, growth rates and foliage colors. Some feature shorter stem nodes between the leaves, reduced root size, and more compact habit.

Spotlight series (lime, red, black foliage) new for 2017 from Ball FloraPlant

SolarPower series (black, lime, red foliage) new 2016 from Ball FloraPlant

Sweet Caroline Sweetheart series (light green, red, purple with heart-shaped leaves)

New for 2017 -‘Sweet Caroline Sweetheart Jet Black’ and ‘Sweet Caroline Bewitched Green with Envy’

Sidekick series (black and lime with different leaf shapes) from Syngenta.

Desana series – new colors, leaf shapes and compact types.

Illusion series from Proven Winners feature thread-leaf foliage, more compact and less vigorous. Cultivars include Emerald Lace, Midnight Lace and Garnet Lace. ‘Bewitched After Midnight’ (maple-leaf-shaped, purplish-black foliage) also from Proven Winners

According to Dr. Allen Owings, these 6 cultivars grow much less aggressive:

Bewitched Green with Envy (more green)
Solar Power Lime
Spotlight Lime
Sweet Georgia Light Green
Sweet Caroline Light Green
Bright Ideas Lime

Credit: update of current varieties provided by Dr. Allen Owings, Research Horticulturist at the LSU Trial Gardens in Hammonds, LA.

Night Blooming Plants For Temperate Climates

Posted by Hugh on April 6th, 2017

Evening primrose in a late June Garden

Hemerocallis ‘Citrina’

If you are working away from home all day long, you might consider growing a few plants that bloom at night. Here’s a short list of plants whose flowers will add beauty to your evening garden:

Evening Primrose (Oenothera glazioviana) – this biennial grows 1-5 feet tall. Plant(s) are basal growing in year one and produce sturdy floral stems the second year. Bright lemon yellow 1 inch diameter blooms are 4-petalled and flower in June and July (in Tennessee). Previous evening blooms decline in late morning.

Citron Daylilies (Hemerocallis citrina) – an evening blooming daylily species whose large bright yellow blooms unfurl on tall flower scapes. Leaves are dark green and very grass-like. Flowers are also highly scented. Clumps do not require dividing for several years. Daylilies prefer full sun and moist well-drained soil.

Moonflower (Ipomoea alba) – showy night blooming vine with heart shaped leaves (annual; zones 9 – 11). Flowers are lightly fragrant; prefers full sun and moist well-drained soil.

Four O’ Clocks (Mirabilis jalapa) – popular flowering annual (zones 8 – 11). True to its name, blooms open late afternoon in full sun to partial shade; lightly fragrant flowers available in yellow, pink, purple, red and white. Plants grow 1.5 to 2.5 feet high and wide and flower from mid-summer into early fall.

Night-flowering Catchfly (Silene noctiflora) – has perfect flowers (both male and female parts), narrower petal lobes, capsules with 6 teeth, and sticky hairs. While both species bloom at night, Night-flowering Catchfly starts closing up in earlier morning while White Campion (Silene latifolia) flowers stay open until noon, and even later on cloudy days (zones 5-9).

Night Blooming Jasmine (Cestrum nocturnum) – a tropical shrub (zones 9 – 11) with non-distinctive white, star-shaped tubular flowers which are strongly fragrant, at times overpowering. Grow outdoors on a deck or patio in full sun and bring back indoors once evening temps drop below 45°F.

Night Blooming Cereus (Epiphyllum oxypetalum) – this member of the Orchid Cactus family requires a period of dryness and cool nighttime temperatures during winter to insure summer bloom. Pure white flowers, the size of a dinner plate, open soon after the sun goes down, remains open all night, and closes the following morning. Blooms are spectacular and highly fragrant. off and on through the summer months.

Night-blooming Tropical Waterlilies (Nymphaea spp.) are easily distinguished from hardy water lilies in that their leaves are serrated or jagged. Tropical lilies come in day blooming and night blooming varieties. Day blooming varieties open several hours after sunrise and close a few hours before sunset. Night blooming varieties open 1-2 hours before sunset and remain open a few hours after sunrise.

These plants are visited nightly by such pollinators as moths, butterflies, bees, bats, and occasionally hummingbirds.

Tropical waterlily (day blooming)

Late Rising Perennials

Posted by Hugh on April 3rd, 2017

Late rising Asclepias tuberosa

Hardy begonia (Begonia grandis)

As air temperatures rise in the spring, most garden perennials and wildflowers are emerging from the ground. With the sudden appearance of 80°F temperatures, many seem to blast through the still cold soil in 1-2 days, and in full bloom a few weeks later. Yet, through the month of April, some of your prized perennials show no signs of life.

A number of these tardy perennials require both warm air and soil temperatures. They’re not rarely fooled by unseasonable warm-ups. In northerly locations (USDA zones 4 and colder), some may not emerge from the soil until June.

When you first plant them, mark the spot with easy to find label so no harm comes, such as digging in the wrong spot. Follow the same practice for spring flowering bulbs such as daffodils (narcissi), tulips or hyacinths. Mark all areas where springtime wildflowers such as Virginia bluebells (Mertensia), trilliums, Jack in The Pulpit (Arisaema), bloodroot (Sanguinea), twinleaf (Jeffersonia), and many others inhabit.

Some perennials that emerge in mid- to late- spring:

Milkweeds (Asclepias spp.)

False Indigo (Baptisia spp.)

Hardy begonia (Begonia grandis)

Leadwort (Ceratostigma)

Crocosmia (Crocosmia x crocosmiiflora)

Joe Pye Weed (Eupatorium spp.)

Whirling Butterflies (Guara lindheimeri)

Perennial hibiscus (H. moscheutos)

Swamp hibiscus (H. coccineus)

Some deciduous ferns – example: Royal fern (Osmunda regalis)

Red hot poker (Kniphofia uvaria)

Russian sage (Perovskia atriplicifolia)

Balloon Flower (Platycodon)

Black eyed Susan (Rudbeckia ssp.)

Indian pink (Spigelia marilandica)

Lady’s Slipper Orchids (Cypripedium), Solomon’s Seal (Polygonatum) and False Solomon’s Seal (Smilacina) may not poke up above ground their first year after planting.

Tips On Growing Azaleas

Posted by Hugh on March 31st, 2017

'El Freda' hybrid azalea at Bellinggraph Botanical Gardens in Mobile, AL

‘El Freda’ hybrid azalea at Mobile Botanical Gardens in Mobile, AL

Red azalea in a Johnson City, TN garden

Evergreen azaleas (Rhododendron spp.) are actually small-flowered rhododendrons. Depending on where you garden, azaleas enjoy a long bloom period from late March (zone 8) to June (zone 4) in the U.S. Many cultivars bloom for two weeks or more. Fall blooming types like Encore® and Bloom-a thon® series are also available.

Azaleas have shallow root systems and most of their feeder roots are near the surface. Dig shallow wide holes in well-drained soil that are amended with lots of organic matter. Water deeply after planting. Water your newly planted azalea weekly if the weather is dry, at least for the first year.

Fertilize azaleas in the spring or fall. Use a granular, slow-release fertilizer that is acid-forming. Established azaleas often do well with no fertilizer at all. If your soil is alkaline (pH>7), add iron sulfate or ammonium sulfate to lower pH to around 5.0. Mulch azaleas with shredded leaves, leaf mold, pine needles, or pine bark mulch keep the soil cool and moist. Shredded hardwood mulch tends to raise soil pH (less acidic).

Prune azaleas just after they finish flowering. Remove all dead, diseased, or weak branches. New buds for next spring’s flowers form in midsummer.

Azaleas shed some of their evergreen foliage naturally. Leaves may turn yellow, red, or purple before dropping. During unusually cold winters, some cultivars may drop more leaves than in mild winters. Flower buds can also be damaged by cold, dry winds. Deer and rabbits will browse over the winter months.

Common pest and disease problems:

Azalea lace bug appears anytime from spring to fall. Insecticidal soaps, horticultural oils, or systemic insecticides manage outbreaks of lace bugs.

If leaf edges are notched, black vine weevil may be the problem. The nocturnal feeding weevil larvae feed on azalea roots at night. Apply pesticide containing ingredient Imidacloprid to manage black vine weevils.

Azalea petal blight may show up when spring weather is unusually wet. Apply a fungicide labeled for petal blight just as the petals begin to show color.

Phytophthora or Pythium root rots may occur if soils are heavy clay and are poorly drained. Amending the soil to improve drainage may help or plant in raised beds.

Fall Bloom-a-Thon® Lavender azalea

Partridgeberry – Evergreen Groundcover For Deep Shady Areas

Posted by Hugh on March 28th, 2017

Partridgeberry (Michella repens) (photo credit: Mt. Cuba Center)

Partridgeberry (Mitchella repens) is grown for its evergreen foliage, spring flowers and winter berries. This native low-growing groundcover can be found in moist woodlands and along stream banks in the Eastern and Midwest U.S. It is a good choice for planting in deep shaded garden areas (USDA hardiness zones 4–8).

In the spring woodlands, small four-petaled white tubular flowers are arranged in pairs above the foliage. Bright scarlet red berries follow late summer, fall and winter. Partridgeberry may re-bloom lightly in fall.

Partridgeberry is a creeping evergreen perennial up to 2 inches high. Round, 1/2 inch wide, bright green leaves form a dense cover all year. Stems root into the soil where they touch and grows non-aggressively. Bare root plants should be set in very early spring and kept irrigated until the new growth has definitely started. Container plants (plugs) may be set at any time.

Grow partridgeberry in full or partial shade and in compost-rich, acidic, well-drained soil. When first planted, young plants need low to moderate watering. Plants become quite tolerant of dry soils after one season. If you observe leaf wilting, irrigate more frequently or move to a shadier site.

Decorative value: Occasionally, I’ve seen partridgeberry utilized in Christmas greenery for the festive bright red berries and dark evergreen foliage. Fruits are favorites of all kinds of woodland wildlife including deer. However, deer cause little damage to the overall vine.

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.