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

Fall Leaf Gathering Turns Into “Black Gold”

Posted by Hugh on November 7th, 2015

Compost in rose bed at Biltmore Estates, Asheville, NC

Compost on rose bed at Biltmore Estates, Asheville, NC

Leaf pile ready for composting

In autumn the cool crisp air paints the land with a colorful array from tree and shrub foliage. As days turn into weeks, leaves fall away and pile up on rooftops, walkways, lawns and gardens. Instead of just raking and tossing them curbside, gather and put them to good use.

Fallen leaves (and grass clippings) can be easily composted, turned into “black gold” and spread as leaf mulch over garden soils or around trees and shrubs, including roses. Leaf mold enriches the soil, locks in moisture, and protects plant crowns and roots from the frigid winter temperatures. You save money by not buying bagged mulch or compost at garden centers.

To speed the composting process, shred leaves and small twigs and branches with a mulching mower, shredder or leaf blower set on vacuum setting. Start with a thin layer of shredded leaves to compost. It decomposes rapidly, usually within a few months. Small twigs and branches decompose more rapidly. Heaping up thick heavy layers garden debris will block air and water from penetrating the pile.

Leaf mold (sometimes spelled mould) is essentially a soil conditioner. It improves soil water retention and soil structure, and creates a living habitat for beneficial organisms such as earthworms and bacteria that nourish the soil.

Distribute only a few inches of leaf mold. Thick layers of composted mulch locks in too much moisture, and smother plant roots that require well-drained soil. Roots become susceptible to rots and other fungal diseases.

The decomposition process for leaves takes at least 6-12 months. It takes very little work on the gardener’s part. To speed up decomposition, mow over the piled leaves once or twice. A few handfuls of nitrogen-rich fertilizer will speed up the rotting process. Turn the pile with garden fork or heavy rake to aerate. Throw a plastic tarp over the pile to keep leaves warm and moist.

Add leftover leaf mold to a compost bin or store remains in plastic bags for later use.

10 Winter Care Tips For Landscape Plants

Posted by Hugh on October 10th, 2015

Recently pruned roses and winter-protecting mulch

Recently pruned roses and winter-protecting leaf mold compost

Do Not Plant Chaste tree (Vitex) in Autumn in zones 6 and 7

Fall-planted perennials, shrubs and trees need some additional attention. Here are 10 basic tips to help plants get past potential winter woes:

Select balled-and-burlapped (b&b) or container-grown plants rather than bare-rooted stock. Most bare-root plants are planted in late winter or early spring when plants are still dormant.
Evergreens, particularly broad-leaved evergreens, are more susceptible to winter dryness because leaves lose more water than narrow-leaved evergreens and deciduous plants. Roots may not replace moisture loss in frozen ground.
Don’t delay planting landscape plants you found on sale at local garden centers at deep discounted prices. Early fall planting ensures good root development.
To Mulch or Not? A 2-4 inch layer of mulch can prevent wide soil temperature fluctuations. Do not mulch newly set fruit trees which may attract overwintering voles and rabbits that feed on their tender sugary bark.
Plant ground covers and shallow-rooted shrubs earlier in fall to avoid heaving out of the ground by alternate freezing and thawing. A 2-4 inch layer of mulch by late November or early December to reduce wide soil temperature fluctuations.
Particularly in northern areas, insulate rose crowns and roots with 4-6 inches of loose non-packing organic mulch such as straw or oak leaves.
Plant bulbs when there is a chill in the air or after first killing frost. In southern areas (zones 6 – 8), garden centers are lowering prices in November to make room for winter holiday inventory.
Cover the trunk of thin-barked young trees with paper wraps in late November to prevent winter frost cracks, sunscald, and deer and rodent damage; remove all wraps by early May.
In most regions prune on the “downside” of winter in March and early April. Choose a comfortable day so to avoid mistakes made in a hurry. In zone 6 marginally hardy shrubs include roses, bigleaf hydrangeas (H. macrophylla), crape myrtles, and chaste trees (Vitex spp.).
Don’t forget to move semi-tender plants in containers into an unheated garage or greenhouse for winter protection. Minimum day/night temperatures should not drop below 40 °F.

Critter-Resistant Flower Bulbs

Posted by Hugh on September 24th, 2015

“Deer Candy” Tulips

Dependable Daffodils

Who doesn’t love colorful flowering bulbs in the early spring garden? Unfortunately, many gardens are terrorized by flower-devouring deer or bulb-chomping squirrels, voles and other critters. When utilizing smelly sprays, expensive fencing, or firearms are not options, plant a wide choice of flower bulbs that critters don’t like.

Start out with long-lived daffodils, also called narcissus. They come in so many varieties, small or large flowers, and in color choices ranging from yellow, white, orange, pink, or bi-colors. Deer and rodents won’t eat them like tulips and most types of crocuses which are candy to them.

Alliums, snowdrops (Galanthus), snowflakes (Leucojum aestivum), camassia, starflowers (Ipheion), glory-of-the-snow and blue squill are also critter-proof. Deer and rodents usually leave them alone. Hyacinthoides, Scilla, Grecian windflowers (Anemone blanda) are also good bets.

Most bulbs naturalize and return to bloom for many years. Planted them in a sunny location and in well-drained soil. Encourage bulbs to naturalize by allowing the foliage to die back naturally after bloom. Do not cut back or braid foliage immediately after flowering. Leaves will store up food via photosynthesis in the new bulbs. Fertilize spring flowering bulbs in late winter with a slow-release fertilizer (Milorganite™, Osmocote™, or specially labelled bulb products).

Certain bulbs such as snowdrop (Galanthus), scilla, winter aconite (Eranthis), and snowflakes (Leucojum) are highly shade tolerant. Bulbs emerge in late winter in open deciduous shade. They receive adequate sunlight through the open deciduous woodland canopy before new tree foliage emerges by mid-spring.

Special situations: In stressful environments when animals are starving, they’ll eat almost any bulbous plant.

Best of The Critter Proof Bulbous Perennials

Ornamental onion (Allium)

Camassia

Glory of the snow (Chionodoxa).

Colchicum (late summer and fall bloomer)

Crocus tommasinianus – Squirrel-proof only

Fritillaria

Snowdrop (Galanthus nivalis)

Spanish bluebell (Hyacinthoides hispanica)

Starflowers (Ipheion)

Snowflake (Leucojum)

Narcissus (Daffodil)

Scilla

Fall Lawn And Landscape Planting Tips

Posted by Hugh on September 21st, 2015

Fall Chores At Biltmore Estates, Asheville, NC

New pansy planting in fall

The combination of warm soil and cool air makes autumn an ideal time to plant new trees, shrubs, perennials, and cool season annuals. You may want to divide certain perennials such as iris, hostas, daylilies, and lots more. Fall weather favors root growth which aids transplants to recover quickly before winter’s chill arrives.

Autumn planting tips:

1. Give plants room to grow. Don’t plant trees or shrubs too close to one another and surrounding structures (home, garage, storage buildings, utility polls). Tall trees can drop loads of leaves and twigs into roof eaves. Look up! for utility lines. Call the gas (and electric) company to locate underground lines before digging.

2. Dig planting holes that are not deep and extra wide (2 -3 times circumference) to accommodate rootballs either at or slightly above soil grade.

3. Adding soil amendments and fertilizer to the planting hole is usually not necessary. A few specific shrubs and trees are exceptions. Staking trees is usually unnecessary unless planting site is very windy.

4. Add 2-3 inches of organic-based mulches, such as pine straw (needles), wood chips or compost around base of newly planted landscape plants. Never pile mulch up around the trunk. The mulch layer offers insulation value; it traps in soil heat so shrubs and trees quickly acclimate to their new surroundings.

5. Prune off diseased, damaged or broken branches before planting.

6. Provide deer and rabbit protection if appropriate.

7. Water newly set plants the same day of planting. Do not assume that seasonal rainfall will be adequate. In some eastern U.S. states, October and November are usually drier than normal. New evergreen shrubs should be deeply irrigated. Overhead sprinkler may run for 3 hours (or 10 hours of drip irrigation) every 8 to 10 days until late November – if rainfall is not plentiful.

8. Complete new lawn seeding and/or renovating by mid-October.

8. Broadcast weed preventatives against early spring cool season weeds such as henbit, ground ivy, purslane, chickweeds, dandelions, and lots others. These weeds grow over the winter and spring months.

Six Notoriously Weak Wooded Trees

Posted by Hugh on September 18th, 2015

‘Bradford’ Pear (Pyrus calleryana) Blooming in Early Spring

Mimosa tree (Albizia julibrissin)

Almost any time is a good time to plant trees – weather permitting. Sort through many great choices and avoid planting weak wooded species. These six tree species are generally short-lived, messy, and insect and/or disease susceptible. A few may also be designated invasive in your state.

Ornamental or Callery pears (Pyrus x calleryana (‘Bradford’ and other cvs.) are popular medium sized flowering tree. In very early spring its upright branches are blanketed with white flowers. This fast growing tree develops weak branch crotches that self-destruct in stormy or windy weather. Ornamental fruits are eaten by birds that distribute the seeds. Ornamental pears may become invasive (USDA hardiness zones 4 – 8).

Silver maples (Acer saccharinium) have a short life span and a rapid growth rate compared to other large maple species. At maturity, a typical silver maple may reach up to 60-80 feet in height. Seedling types possess weak branches which tend to break in ice storms or high winds. Some improved hybrids and cultivars such as ‘Silver Queen’ exhibit a sturdier framework.

Weeping willows (Salix spp.), including corkscrew willow (S. matsudana ‘Tortuosa’), are weak wooded. During the spring and summer, willows drop lots of twig and leaf debris. Willows are susceptible to numerous disease and insect problems (USDA Plant Hardiness Zones 4b – 8).

Siberian elms (Ulmus pumila) are very large fast growing weak-wooded tree (100 feet not uncommon). They’re exceptionally messy and litter turf and ground areas year-round. As its name hints, species is extremely cold hardy, but is not heat tolerant in Southern U.S. landscapes (USDA Plant Hardiness Zones 4 – 8).

Mimosa trees (Albizia julibrissin) develop into a lovely summer flowering small tree with pink feathery flowers and fine textured foliage. Unfortunately, these summer-flowering trees are short-lived, weak-wooded, and seeds in readily from trees many miles away (USDA hardiness zones 6 – 9).

Poplars and cottonwoods (Populus spp.) grow up to 5 feet to 8 feet a year, some species reaching 40 feet to 60 feet in height. Their weak branches spread 20 feet to 35 feet apart and are dangerous to house and autos. Leaves and branches are highly susceptible to numerous diseases and insects. In rural areas poplars are often planted in rows as windbreaks along perimeters of properties (USDA Plant Hardiness Zones 3 – 9).

In summary, most quick-growing trees are weak wooded, produce lots of seeds and/or messy fruits, root sucker badly, and are disease and insect susceptible.

Rebloomers Need Your Help

Posted by Hugh on August 12th, 2015

Rebloomer daylily (Hemerocallis ‘Stella D’Oro’)

Iris ‘Immortality’ at NC Arboretum in Asheville, NC

Re-bloomers are specific cultivars that bring on a repeat floral show – two and sometimes three in one season. In my garden re-blooming iris and re-blooming daylilies return for another round of bloom in late summer and fall. Also, deadheading some perennials will cause them to flower again.

You, the gardener, must supply needed soil moisture and nutrition (primarily nitrogen) as these plants should not struggle through an environmentally stressful summer. Plant vigor gets recharged by frequent irrigation and adequate fertilizing. In some situations you may need to monitor and treat disease and insect problems.

As plants finish blooming in “prime time”, remove all spent flower heads to prevent seed formation. For iris prune off old flowers in late May, daylilies in late June and July.

Deadheading: some perennials re-bloom a second and third time when old spent flowers are promptly removed, and plants are properly nurtured. Here are a dozen of easy to re-bloomers: yarrow (Achillea), blanket flowers (Gaillardia x grandiflora), perennial salvia (Salvia x nemorosa), tickseed (Coreopsis verticillata), coneflower (Echinacea purpurea), redhot poker (Kniphofia), gayfeather (Liatris spicata), summer phlox (Phlox paniculata), Shasta daisy (Leucanthemum x superbum), blackeyed Susan (Rudbeckia fulgida), Stokes aster (Stokesia) and speedwell (Veronica spp.).

Note: not all daylily and iris varieties are re-bloomers.

Beware! Yellow Jackets

Posted by Hugh on August 6th, 2015

Paper wasp (photo by Dr. Frank Hale, University of Tennessee Entomologist

Most humans fear and hate yellow jackets. They are actually wasps and important predators of several harmful insects. They’re easily identified by their distinctive markings along their abdomen. They tend to dart about rapidly, in a side-to-side flight pattern. Female yellow jackets are the ones capable of stinging.

Wasps (Vespula spp.) are not bees; they’re brightly colored “cousins” of ground bees. In late summer, while most ground nesting bees are storing up food for the winter, wasps begin to emerge. They had constructed their nests in cool spots such as old rodent burrows, ground holes, under roof eaves, and in mortar cracks between bricks of buildings.

Yellow jackets are social insects. They are not pollinators, but do prey on other pollinating insects and nectar. They scavenge on animal wastes and foods high in protein or sugar. Wasps are highly aggressive and are easily provoked by humans. Favorite places to forage include waste receptacles, soda cans, and picnic foods which they carry back to their nest.

The aggressive behavior of yellow jackets, coupled with their tendency to attack as a group, makes them formidable pests to deal with. When outdoors follow these few wasp avoiding tips. Keep all liquids covered. Don’t swat or crush yellow jackets as this may incite other yellow jackets to attack. If you get too near a nest, backoff slowly. Do not wear bright colored clothes or heavy perfumes.

Call a professional exterminator who has the knowledge, safety clothing, and proper pesticides to find and destroy nests close by your home or patio. Otherwise, leave these mostly beneficial insects alone.

List Of Conifer Reference Gardens In Southeastern U.S.

Posted by Hugh on August 1st, 2015

American Conifer Society Reference Gardens in the Southeastern Region

March 2015

Platycladus orientalis ‘Franky Boy’ at UT Gardens, Knoxville, TN

Pinus wallichiana ‘Zebrinus’ on ETSU Campus in Johnson City, TN

Want to learn about which evergreen and deciduous conifers grow well in your area. The American Conifer Society (ACS) has established a reference garden network across the U.S. If you are developing dwarf conifer collection and want to know their growth rates, visit a reference near you. These public arboretums and botanical gardens are also wonderful vacation destinations.

At this writing eleven (11) gardens have been designated in the Southeastern U.S. Here is the current list:

Gardens of the Big BendUniversity of Florida

155 Research Road

Quincy, Florida

University of Tennessee – JacksonWest TN Research and Education Center Gardens

605 Airways Drive

Jackson, Tennessee

Atlanta Botanical Garden1345 Piedmont Avenue NE

Atlanta, Georgia

University of Tennessee GardensUniversity of Tennessee

2431 Joe Johnson Drive

Knoxville, Tennessee

Lockerly Arboretum1534 Irwinton Road

Milledgeville, Georgia

Al Gardner Memorial Conifer GardenJ. Sargeant Reynolds Community College

1851 Dickinson Road

Goochland, Virginia

Smith Gilbert Gardens2382 Pine Mountain Road NW

Kennesaw, Georgia

Lewis Ginter Botanical Garden1800 Lakeside Avenue

Richmond, Virginia

State Botanical Garden of Georgia2450 S. Milledge Avenue

Athens, Georgia

Norfolk Botanic Garden6700 Azalea Garden Road

Norfolk, Virginia

Hatcher Garden and Woodland Preserve820 John B. White, Sr. Blvd.

Spartanburg, South Carolina

State Arboretum of Virginia400 Blandy Farm Lane

Boyce, Virginia

South Carolina Botanical GardenClemson University

150 Discovery Lane

Clemson, South Carolina

Baker Arboretum4801 Morganton Road

Bowling Green, Kentucky

East Tennessee State University ArboretumEast Tennessee State University

Johnson City, Tennessee

JC Raulston Arboretum4415 Beryl Road

Raleigh, North Carolina

Memphis Botanic Garden750 Cherry Road

Memphis, Tennessee

Delightful Dragonflies And Damselflies

Posted by Hugh on June 27th, 2015

Dragonfly (Photo by Dr. Frank Hale, UT Entomologist, Nashville)

Damselfly (Photo from Dr. Frank Hale, UT Entomologist, Nashville, TN)

Watch them flitter… Dragonflies and damselflies, also called “darning needles” and “dining needles”, are common spring/summer inhabitants in many U.S. gardens, particularly around water gardens, streams and other water features, where they reproduce. Adults lay eggs on the plants around the water’s edge; the nymphs hatch from the eggs and live under water for months or years before they mature and fly. These insects are in the order Odonata.

Dragonflies and damselflies are beneficial insects and delightful to watch. Young children enjoy seeing them flit around reeds, lilypads, and flowers; children frequently cause panic when they fly to close. However, they do not sting or bite people. Dragonflies and damselflies are predators of other insects, including mosquitoes and beetles. They have excellent eyesight and are fast nimble fliers.

Both dragonflies and damselflies tend to stay close to where they were born. Key differences between them is that dragonflies rest with their wings held open; damselflies fold their wings back over their abdomens while resting. Some people refer to dragonfly nymphs (immatures) as “skimmers”.

Dragonflies live around water ponds and features, such as a large urn or half whiskey barrel filled with water. Dragonflies are most active on warm spring and summer days. They prefer ponds with plants growing in or around it where the nymphs can hide and hunt. Young fliers will rest (bask) on rocks and twiggy shrubs; tall cattails, reeds and grasses are great places to perch on.

Dragonflies and damselflies are an important food source for various birds. Pond fish or frogs will prey on the nymphs.

Credit: idea for blog originates from writings of Rick Darke and Doug Tallamy whose books on garden ecology should be general reading for children and adults.

Persian Shield Offers Radiant Foliage Color

Posted by Hugh on June 24th, 2015

Persian shield and coleus at Biltmore Estate, Asheville, NC

The iridescent purple foliage of Persian shield (Strobilanthes dyerianus) radiates in a warm summer garden in the U.S. Here it is treated as an annual (USDA hardiness zones 9-11). Persian shield is native to tropical Myanmar (formerly Burma), where it is a 3-4 feet tall soft-stemmed evergreen shrub or subshrub. In temperate regions it grows only 1-3 feet.

Dark green leaves (to 8 inches long) are flushed with silvery-purple variegation above and dark purplish tints beneath. In the tropics, tiny violet 5-lobed flowers appear in short cone-shaped inflorescences. It rarely blooms in non-hardy regions.

Persian shield prefers compost-rich, moist and fertile soil. Two keys to successfully growing Persian shield are light exposure and plentiful soil moisture. Depending where you garden, plant in full sun or partial sun or moderate shade. It thrives in the heat and humidity of the southeastern U.S. In cooler areas (zones 4-6), full day sunlight is ideal. Where summer temperatures sizzle, a few hours of early morning sunlight is adequate. Partial shade brings out the deepest purple in the leaves.

From spring through summer Persian shield plant responds to constant feeding. Fertilize it with a water soluble products such as Miracle-Gro™, Nature’s Source™, or Daniels™ at half rate and twice as often (contrary to package directions) to maximize shoot growth and not to burn the roots.

Pinch stems every few weeks to develop a compact, bushy plant. Use the pinched cuttings to start new plants (see below). Otherwise, Persian shield will develop a 3 feet stem, that will likely need staking to prevent flop over. Persian shield has few, if any diseases and pest problems. Occasionally, spider mites may discolor the leaves.

In the fall, with killing frost pending, take cuttings from garden plants and grow them as house plants over winter. Cuttings easily root within 3 weeks in moist sand and/or vermiculite and held in a plastic tent for high humidity. Provide moderate light, but not direct sunlight, so as not to burn the tender unrooted cuttings. Transplant into good potting soil and keep adequately watered and fertilized until mid to late spring.