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

Fall Trimming Of Perennials

Posted by Hugh on October 23rd, 2017

Christmas fern -winter evergreen

Miscanthus ‘Morning Light’-late winter

You do not need to cut perennials back in the fall, but many gardeners do so as part of the garden cleanup. Don’t rush the job. Leaves of many perennial plants continue to produce and store carbohydrates in crowns and roots until they go fully dormant. Wait until after the first hard frost or until leaves have turned yellow or brown before cutting back plants back. The old growth may also carry over diseases, particularly mildews and botrytis and re-infect new spring growth.

There is no hard fast rule how far to cut back plants. For most perennials, prune them back to about 2 to 3 inches from the ground. Cutting off at ground level may damage the plant crowns where the new shoots emerge in the spring.

Do not cut back evergreen perennials such as assorted ferns, coral bells (Heuchera spp.), and lenten roses (Helleborus spp.) in the fall. You may trim off spent flower stems and any tattered and dead basal leaves. For most vines, wait until they are completely dormant before trimming them back. Trim them high, leaving at least 6 inches and more.

For some perennials which grow shrub-like, it is best to wait until late winter. However, the following perennials may be injured: silver mound (Artemisia), butterfly shrub (Buddleia), Blue mist shrub (Caryopteris), lavender (Lavandula), and Russian sage (Perovskia). With these perennials, wait until new spring growth starts to emerge before clipping off the old growth.

Again, it is not necessary to cut perennials back in the fall. Many perennials also provide winter interest to an otherwise drab landscape. Examples include ornamental grasses, coneflowers, goldenrods, and evergreen ferns. Ornamental grasses are architectural wonders. Lastly, seeds from coneflowers (Echinacea), blackeyed Susans (Rudbeckia), globe thistles (Echinops), goldenrods (Solidago), and yarrows (Achillea) are important food sources for overwintering birds.

Plant American Beautyberry For A Fall Show

Posted by Hugh on October 20th, 2017

American beautyberry at NC Arboretum in Asheville, NC

Colorful fall fruits

American Beautyberry (Callicarpa americana) is a loose open growing shrub valued for its spectacular fruits in the fall (USDA hardiness zones 6-10). The growth rate of this native shrub is rapid, eventually reaching 4-7 feet in height and 4-6 feet in spread within 5 years after planting.

Beautyberry thrives in a moist, humus-rich, mildly acidic, well-drained soil and in a mostly sunny spot in the garden. It will grow well in partial sun, although fruits are not as showy in shady areas. Group several plants together for better fruit numbers.

Small clusters of pink flowers are born in the axils of the leaves from late June thru August and mostly go unnoticed. Flowers lead to a showy display of brightly colored fruit clusters that will catch your eye and those of friends and neighbors. The magenta to violet berries are 1/5” in diameter. Leaves may turn faint pink or yellowish in fall before dropping.

Beautyberry requires little annual care (other than pruning) after its first year in your garden. Feed annually with 10-10-10 granular fertilizer (or equivalent). Lay down a fresh 2-3″ layer of mulch as a weed preventative and to conserve soil moisture. It is not troubled by any significant disease or insect problems. Beautyberry is propagate by vegetative cuttings or from seed.

Every 2-3 years, in late winter or early spring, this vigorous growing shrub should be pruned to control its size and shape. A multi-year unpruned shrub may also be severely cut back to within 6 inches from the ground. It should flower and bear lots of fruits by fall.

No question that beautyberry is most valued for its spectacular fruits. Berries are important food source for many species of birds and other wildlife. Summer flowers attract butterflies.

Native beautyberries are not frequently found at garden centers that prefer selling the Asian cultivars.

Planting A Rock

Posted by Hugh on October 17th, 2017

“Planted” Landscape Rock with Fall Pansies

Boulder for sale at local garden center

A well placed landscape rock or boulder is a perfect garden feature. Planted properly, the boulder appears to emerge naturally from the bowels of the earth. The crowning achievement is when mosses and lichens find a home in its crevices or when vines crawl over them.

Boulders may exhibit seams of color(s), deep crevices, and/or have jagged or rounded edges. Is the rock, stone , or boulder best displayed from a vertical or horizontal position? Boulder may provide multiple landscape uses from a child climbing over it or the gardener looking for a comfortable sitting stool.

A recent addition to our garden is a 250 pound rock (photo on left). Our stone has a broad muscular base and a flat gray/blue face (side facing the street). On rainy day the darker blue color comes forth. A couple of strong friends help move, orient, and set the rock in its permanent spot. We “posed” our rock, turning it to catch its showiest side(s) from inside the home and curbside. Neighbors, joggers and and dog walkers get to view the muscular side from curbside.

A wide shallow hole was dug around the base to “root” and support the boulder firmly. Plant your rock shallow! Its mass (bulk) and weight, along with gravity, will eventually settle a heavier boulder deep. On soft ground, add 2-4 inches of gravel or sand and tamp it down for firmer base. Be absolutely certain that the rock is firmly anchored and will not tip or roll and hurt a young child climbing over it.

Around the rock you may wish to plant low growing plants such as pansies, flowering bulbs, sedums, coral bells, cranesbills, astilbes, or ferns.

Restful sitting place at Biltmore Estate in Asheville, NC

‘Youngii’ White Bark Birch A Novelty Tree For Small Spaces

Posted by Hugh on October 13th, 2017

‘Youngi’ birch at NC Arboretum in Asheville

Newly planted ‘Youngi’ birch

Young’s Weeping European Birch (Betula pendula ‘Youngii’) is small graceful tree with willowy pendulous branches (USDA hardiness zones 3-6). Nurseries often train the very pliable branches and trunk of grafted seedlings into unique novelty shapes.

Plant this miniature 12 to 20 feet tree specimen near a deck or patio where it should receive mostly morning sunlight. Fall foliage turns bright yellow. In late winter 3-inch male catkins, hanging from its slender branches swell, a sure signal that spring is close at hand.

The key to growing Youngi (or any white bark birch) successfully is to maintain a stress-free growing setting. This noveltry tree requires more care and pesticide spraying than most landscape plants. Unfortunately, twigs and branches are highly susceptible to bronze birch borers and leaf miners which turn leaves brown by late summer unless sprayed every few weeks. Apply the proper insecticidal controls and cultural conditions for best growth.

When planted in cool temperate areas of the U.S., particularly in northern tier of New England and Midwestern states, European birches live several decades. The tree’s leaf canopy is not dense and surface roots tend to dry out rapidly. Irrigate deeply the first growing season to develop an extensive root system. Maintain a 2-3 inch mulch depth around the root zone to cool surface roots. Weekly summer irrigation also aids in cooling the ground. Feed with slow release fertilizer in early spring.

Pruning, if needed, should be performed in summer to early fall and do not prune excessively. Spring pruning should be avoided as sap will bleed profusively from pruning cuts; sooty mold disease frequently follows, growing over sweet sap and blackening the beautiful white sap. Avoid excessive pruning, e.g. removing more than 20% of total branching. Pruning at the wrong time also can lead to borer infestations.

Nuts About Acorns

Posted by Hugh on October 10th, 2017

Acorn germinating into soil

Acorns are nuts that form on mature oak trees (Quercus spp.). Acorns come in many shapes, sizes and colors, depending on the species. An acorn is a single nut encased in a hard shell by a cap (used to identify what oak species it is). For example, Northern Red Oak (Q. rubra) tree produces egg-shaped acorns and are supported by shallow, saucer-shaped cup. White oak (Q. alba) produce acorns that are stubby and covered with warty cups.

Some oak species produce acorns almost every year, while on others acorns two years to mature. Older mature oaks, usually past 20 years old, produce many more acorns, and 70 or 80 year old trees can potentially produce thousands of nuts.

Many animal species rely on acorns as a food staple, such as squirrels, woodpeckers and deer (termed “mast”). Humans consume roasted acorns; right off the tree acorns are full of tannins, which can be toxic if eaten in high amounts. Acorns from the white oak group are low in tannin and have a nutty flavor when lightly roasted before grinding. Many acorns, cached away by squirrels and bluejays, will eventually germinate and become the next generation of oak forest.

Within its hard shell, an acorn contains one seed. The oak seed must not dry out or it will not germinate. To prevent drying, tree growers will collect and store acorns in plastic bags in the refrigerator for planting late next spring. Acorns need 1,000 hours of dormancy in low temperatures (33-37 º F). The larvae of some moths and weevils also live in acorns, consuming the kernel as it develops. These pests may consume more than 95% of all acorns in some years.

Acorns are rich in large amounts of proteins, carbohydrates, fats, vitamins, as well as the minerals such as calcium, magnesium, phosphorus, and potassium. Do not permit grazing animals to eat large amounts of acorns from specific Quercus species, especially red oak group and English oak (Q. robur).

Acorns of the white oak group typically start rooting as soon as they come in contact with the soil (in the fall). For example, bur oak (Q. macrocarpa) acorns fall from the tree from August to November. Germination usually occurs rapidly after seed fall, and favors root growth first. The taproot penetrates deeply into the soil. Contrarily, acorns from the northern red oak group drop in late fall, remain dormant through winter, and germinate in the spring.

These oaks are designated as “State Trees”:

White oak (Q. alba) – state tree of Connecticut, Illinois, and Maryland

Live oak (Q. virginiana) – Georgia state tree

Northern Red oak (Q. rubra) – New Jersey state tree

Bur oak (Q. macrocarpa) – Iowa state tree

Scarlet oak (Q. coccinea) – District of Columbia tree

Comparing Heritage® Vs Duraheat® River Birch

Posted by Hugh on October 6th, 2017

‘Duraheat’ at the NC Arboretum in Asheville, NC

Summer chlorosis caused by high soil pH

In general, most species of our native birches (Betula spp.) grow best in cool, northern areas of the U.S. They are found growing along the sides of rivers, lakes, streams, and mountainous areas (USDA Zones 4-9). Most birches (not all) are recognized for their distinctive gray to white bark. Birch species with the whitest of bark are not heat tolerant, insect and disease prone, and usually are short-lived in zone 6 and points south.

Compared to other species of birch, river birch (B. nigra) is more heat tolerant and is highly insect- and disease-free (USDA hardiness zones 3-9). Heritage® and Duraheat® are two exceptional cultivars of river birch that have changed our overall view of the species. Both grow almost identically at 40 feet high and 30 feet wide. Catkin-like flowers swell over the winter months and open in early spring.

Both cultivars are mostly purchased multi-trunk with a broad pyramidal architecture. Summer foliage is medium green and glossy and turn bright yellow in the fall. Heritage and Duraheat were selected for their lighter colored bark and medium green glossy leaves. To date, Heritage is the more popular, but Duraheat is preferred in southern climes. The mottled peeling bark exposes patches of cream, orange and pinkish tan colors within. Both are highly resistant to bronze birch borer.

River birch prefers a moist slightly acidic soil, and once established, it adapts to moderately dry ground. Mulch with pine needles or pine bark to favor an acidic soil. Otherwise, leaves may turn chlorotic (yellow) in summer if soil pH runs slightly alkaline. Feed with a slow release fertilizer such as Osmocote™ or Nutrikote™ in early spring. If soil pH becomes alkaline, apply elemental sulfur or chelated iron (follow precise package directions). Birches are bleeder species and are best pruned in summer.

River birch trees grow rapidly and require minimal annual care. Tree exhibits 4-season landscape interest. They are often planted in parks, golf courses and other public areas. Homeowners plant clump-growing river birches around deck and patio areas. Fall leaves decay rapidly and are an easy clean-up.

Halloween Pumpkins And Gourds

Posted by Hugh on October 3rd, 2017

Swan Gourds

American Tondo gourd

It’s Pumpkin Time!…celebration of Halloween across America. A local pumpkin farm had over 60 kinds of pumpkins to choose from.

According to the Missouri Botanical Gardens website: “the term pumpkin really has no botanical meaning”. Pumpkins and gourds are classified as squashes in the Cucurbitaceae family along with cucumbers and melons.

If you want to grow pumpkins and gourds, they require fertile soil and lots of fertilizer to support the vines and fruits. Apply 2-3 lbs. of 19-19-19 (N-P-K) per 1000 square feet at planting time followed by an additional 1-2 lbs. per 1000 sq. ft of bed of actual nitrogen (N) or ammonium nitrate at 3 – 6 lb. per 1000 sq. ft. rate in mid-summer. Irrigate as needed and keep vines mulched.

Pumpkins and gourds are threatened by several potentially serious diseases (anthracnose, downy mildew, powdery mildew, and alternaria) and insects (striped and spotted cucumber beetles, vine borer, and aphids). Crop rotation is very important. Grow on new ground each year. Consult your local Extension office or state university for the latest Pesticide Recommendations to manage pests and diseases on gourds. Luffa types are generally tolerant to insects and diseases. Be “Bee Aware” and other important pollinators of vegetable crops.

Wagon full of ‘Casperita’

Proper harvesting is just as important as growing pumpkins and gourds. Fruit skins are sensitive to injury. Luffa gourds are thick skinned and are harvested when the fruits turn brown. Cut gourds with a sharp knife or pruning shear. Leave some of the stem remaining, as stemless gourds are not as ornamental for decoration.

Wash fruits with a mild non-bleaching detergent and with a soft brush. Space gourds apart (not touching) in a dry place with good ventilation and out of the sun. Once thoroughly dry and hardened, gourds can be waxed and/or decoratively painted.

Saving Seeds – this is a common practice. However, many types freely inter-pollinate and their progeny may not look the same. The saved seeds are collected, dried, and stored in a cool, dry spot for 3 to 4 years.

First Days Of Fall…. Bring In Your House Plants

Posted by Hugh on September 30th, 2017

Schefflera

Norfolk Island Pine

The final days are summer are over. It’s time to move your tropical plants indoors before night temps in the low 40°F arrive. These plants thrive outdoors in summer temperatures and high humidity, but cannot survive being left outdoors. Container plants such as Ficus (rubber) trees, orchids, Norfolk Island pines, scheffleras, bromeliads, gardenias, palms, and lots more should be brought indoors. Cacti and succulents have probably doubled in size in the humid summer air and may need to be repotted.

Inspect and eliminate all bugs and diseased leaves before bringing plants into your home. Apply an insecticide labeled for houseplants. Insecticidal soaps are quite effective both inside and outside the home. Do not spray pesticides like malathion and diazinon indoors. Target aphids, mites, mealy bugs, and scales. Also inspect for freeloaders or nuisance pests such as earwigs, boxelder bugs, sowbugs, ants, and squash bugs which often hide on the bottom of pots. Some of these bugs multiply like crazy once they get inside your home.

If you have a garage or breezeway that receives filtered sunlight, move the plants into this halfway shelter for a week or two to acclimated to the lower light conditions indoors. Once inside, a room with a south- or east-facing window is ideal for most tropicals, although desert plants like cacti are best set in a west-facing window.

Put your plants on a diet, e.g. from fertilizer and water. Light levels are reduced and room temperatures are cool (65 to 72°F) through fall and winter seasons. Water plants every 7-10 days and mist tropicals every day to raise room humidity.

Winter Planting –Why Not!

Posted by Hugh on September 27th, 2017

Needle scorched Arborvitae after cold dry winter

Healthy Mix of Evergreens

For those who live in northern regions where winters are cold and snowy (USDA hardiness zones 3-6), many (not all) gardeners can still plant many kinds of trees, shrubs and perennials in late fall and winter if the ground is not frozen. Deciduous plants are in their natural period of rest or dormancy. This does not include evergreen trees and shrubs.

Deciduous vs Evergreens

Fall planting of deciduous trees works better because their need for water is a lot less in winter. Evergreens retain their leaves/needles all winter. Leaf metabolism is a lot less than in summer. Once the ground freezes, roots have trouble foraging for water, and by late winter, leaves/needles may become scorched along the edges, turn brown or die. Fall planting can be more difficult for broad-leaved evergreens like rhododendrons or hollies (Ilex). Mulch around evergreens before the ground freezes to trap in soil warmth and stimulate root growth.

Soil -Water Availability

Across the U.S., winter weather is very different. In the upper Midwest, the fall season is short, and winter is usually long and frigidly cold. The ground freezes early and stays through early spring in most years. Here, spring planting is more reliable with plentiful rainfall.

Along the Pacific coast (Washington, Oregon, and California), fall-winter planting makes sense. Summers are hot and very dry. Fall and winter are long cool periods with lots of rainfall that is ideal for root growth. The ground rarely freezes along the coastal areas.

Plant availability is a significant concern. Generally, garden centers and nurseries do not holdover huge inventories of trees and shrubs. Finally, in regions where winters are cold, magnolia, dogwood, tulip tree, sweet gum, red maple, birch, hawthorn, tulip poplars, cherries, plum and many oak species are more susceptible to winter injury (Purdue University study).

Sizing Up Crape Myrtles (Including Most Recent Introductions)

Posted by Hugh on September 24th, 2017

Delta™ Jazz crape myrtle at UNiv. of Tennessee Gardens, Knoxville

Delta™ Flame crape myrtle

Hybrid crape myrtles (Lagerstroemia fauriei x indica) have undergone significant makeovers over the past quarter century. Several new cultivar series continue to arrive garden centers, including: Black Diamond™ series, Enduring Summer™, Delta™ series, and Magic™ series.

In landscape terms size is very important and gardeners often make a serious error when not calculating the size of crape myrtle for the planting space. Crape myrtles fall into four size categories. Included here are a sampling of the major cultivars based on popularity in the mid-South region (Northern Atlanta thru Eastern Maryland):

Four Height Groups and Flower Color

Dwarf (less than 5 feet)
‘Pocomoke’ – rose pink
‘Berry Dazzle’ – fuchsia
‘Cherry Dazzle’ – vibrant red

Semi-dwarf (5 to 12 feet)
‘Acoma’ – pure white
‘Dwarf Centennial’ – lavender
‘Hopi’ – light pink
‘Tonto’ – fuchsia (red)
‘Zuni’ – medium lavender

Intermediate (13 to 20 feet)
‘Apalachee’ – light lavender
‘Dynamite’ – cherry red
‘Lipan’ – medium lavender
‘Osage’ – light pink
‘Sioux’ – dark pink

Tree type (23 feet and higher)
‘Carolina Beauty’ – dark pink
‘Muskogee’ – light lavender
‘Natchez’ – white
‘Tuscarora’ – dark coral pink
‘Tuskegee’ – dark pink, almost red

New crape myrtle series:

Black Diamond™ Series – 10 to 12 feet high and 8 feet spread with almost black foliage. Currently there are 9 cultivars ranging from red shades, pink shades, white, purple, and lavender.

Magic Series™ from First Editions® is a selection of intermediate size crape myrtles with glossy disease-free foliage; they bloom all summer into fall and hold their leaves until late. Currently there are 8 cultivars in the series of various sizes and color range.

Delta Series™ are part of the Southern Living Plant Collection (USDA hardiness zones 7-9); there are currently four cultivars in four colors: white, red, lavender, and light pink; foliage- unique burgundy, cupped leaves; grow between 6-10 foot tall.

Enduring Summer™ are part of the Garden Debut Plant Collection (USDA hardiness zones 7-9); there are 6 cultivars and grow 4-5 feet tall and wide