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

Are Your Trees Hazardous?

Posted by Hugh on October 28th, 2014

Mature Tree Removed By Certified Arborist

Silver Maple tree rotted at base

Is a hazardous tree lurking in your yard, ready to fall on your house or car? Take a few minutes to inspect trees on your property. Peek over the fence at your neighbor’s trees as well.

Some property owners have an unnatural fear of trees. Well-shaped landscape trees with no dead wood, good growth rate, and a full canopy (top) are rarely a risk. Yes, it’s true that the healthiest of trees are likely to be injured in a “category” hurricane or tornado.

Tree care goes along with tree ownership. Tree health, like people health, changes as they age. Middle-aged trees are less hazardous than mature trees. Age plus a category storm may inflict enough damage to render a tree hazardous.

Location is another factor. A tree deemed hazardous, but not growing near people, houses, and autos, is unlikely to inflict serious injury when it falls. Your insurance company may never hear from you. Trees in a public park, along streets, or in residential zones should be inspected, then pruned or removed.

Trees may show decay or cavities along the main trunk(s) and branches, and timely pruning usually cures most ills. It’s like going to a dentist. A cavity represents wood decay and branch weakness. Decay can be slowed by cleaning out the wound and spraying a pesticide to prevent wood boring insects from habitating.

Different tree species possess different mechanical strengths and decay mechanisms. Weak wooded species considered potentially hazardous include silver maple (Acer saccharinum), cottonwood and hybrid poplars (Populus spp.), willows (Salix spp.), boxelder (Acer negundo), ornamental pears (Pyrus calleryana), and tree-of-heaven (Ailanthus altissima).

A certified arborist can measure the extent of the tree decay using a Resistograph®. A hollow tree cavity is not always hazardous. Tree cavities that are surrounded by at least one inch of solid wood per six inches of tree diameter are unlikely to fail.

Hire only a certified, licensed and insured arborist. Certification is awarded through the International Society of Arboriculture (ISA) following extensive study and testing.

Rebuilding A Storm Damaged Young Tree

Posted by Hugh on October 25th, 2014

Same Sweetbay Magnolia 4 years later

Magnolia virginiana cutback

An enormous 60 foot white pine toppled over several smaller trees. The aftermath was a severely damaged 3- year old sweetbay magnolia (Magnolia virginiana). Replacing the 3 1/2 inch diameter tree would have cost the homeowner over $300. My recommendation to the homeowner was to cut back the magnolia trunk to approximately 12 inches from the ground in late winter or 6 inches above the graft union. While not much remained above ground, the grafted tree still retained 100% of its root system. Nearly 4 years later and after considerable timely pruning, the tree has completely regrown.

A few tree facts: Inside the trunk wood are several latent (adventitious) buds. Survival is what the tree is trying to do. Several multiple shoots pushed out in the spring from above and below ground. All growth below the graft union is from its seedling rootsystem and must be promptly removed, as to not compete with the preferred cultivar.

To create a new tree, prune off short or weak shoot growth, favoring the tallest, thickest, and straightest 1, 2 or 3 new shoots by mid-June (year one). You are deciding whether your new tree will be single or multi-trunk. All energy (growth) will be pushed into the selected shoots. No staking should be needed. Your “new tree” should be 3-4 feet by mid-September.

In early spring feed the stubbed tree with 10-10-10 or equivalent fertilizer; repeat that practice over the first 5 years. Mulch around the tree base, but do not pile mulch against the trunk. Over the next 2-3 years continue to prune off new shoots and root suckers which may form around the trunk base.

Prep Garden Soil In The Fall

Posted by Hugh on October 22nd, 2014

Pine bark amendment at a nursery

Often, spring arrives with too many gardening chores to handle. Some work can be shifted to the fall. Since a garden is only as good as its soil, fall is a good time to till your garden or to construct new beds. Add soil amendments such as deciduous leaves and pine needles which nature is providing for free. Till amendments into the soil with a shovel, multi-tined garden fork, or rototiller.

You may add organic nitrogen sources such as blood meal, animal manures (either packaged or fresh from a nearby farm). Fresh manure may be too hot to use in the spring, but will lose its hot urea properties over the winter. Incorporate digested (decayed) compost pile(s) into your garden soil. Soil microbes do most of the work decaying the organic additives over winter.

Shredded leaves, eggshells, coffee grounds, and fruit peels are all great soil additives; most will break down before spring planting season arrives. Caveat: huge quantities of undigested materials can rob the garden plants of nitrogen next summer. In such cases, you may need to add lots more fertilizer to feed both the garden plants and soil microbes.

The final step before spring is test the garden soil at a state soil lab operated by your state land grant university. Some full-service garden centers may also provide soil testing. Collect the soil sample before the lab’s mad spring rush begins. The local county or area Extension agent will interpret the diagnostic results for you.

The amended soil will be a lot easier to plant into next spring. Fall tilling also buries weeds and weed seeds to reduce this chore next summer.

Evergreens For Wet Soggy Soils

Posted by Hugh on October 19th, 2014

Emerald™ arborvitae at Daniel Stowe Botanical Garden, Gastonia, NC

Most needle evergreens falter in moist soggy soils. These sites usually have a heavy clay or fine particle sand content. Some arborvitaes (Thuja spp.) and Atlantic white cedar (Chamaecyparis thyoides) tolerate temporary wet soggy conditions better than most evergreens (USDA hardiness zones 3-8). An assortment of shapes, sizes and colors are available. All are U.S. natives.

Eastern arborvitae (T. occidentalis) tolerates dry to boggy wet sites. Emerald™ and ‘DeGroot Spire’ is two popular favorites, growing 12-15 feet or 8 feet tall respectively over 15-20 years. The scale- like foliage is uniquely twisted and spiraled. ‘Hetz Midget’ or ‘Tiny Tim’ are dwarf globe or ball forms that grow 12 inches tall and 16 inches wide. The light green scaly foliage turns bronze over winter.

Western arborvitae (T. plicata)) also tolerates tight wet soils. It grows tall and is fast-growing with a tightly pyramidal growth habit. Most popular is the hybrid ‘Green Giant’ (T. plicata x T. standishii) cultivar. Summer foliage is dark glossy green and bronzes over winter. Green Giant grows to a mature height of 50-60 feet tall and 8-10 feet wide. For something very different, ‘Whipcord’ is a dwarf cultivar with unusual thread-like branches and an arching plant habit. It grows to only 2 feet tall by 3 feet wide in 10 years.

Atlantic white cedar (C. thyoides) (zones 5-9) is often observed growing on soggy sandy sites, but dislike clay soils. Winter foliage turns a deep plum color and back to green by the start of spring.

Three popular selections of C. thyoides include:

‘Rubicon’, aka ‘Red Star’ – upright dense form with star-like foliage (6 feet tall by 2 feet wide).

‘Heatherbun’ – compact, globe-shaped form (6 to 8 feet tall by 4-5 feet wide).

‘Shiva’ – dwarf multi-stemmed form with upright spreading branches and silvery lacy foliage (5 feet tall by 4 feet wide) .

Bird’s Nest Spruce

Posted by Hugh on October 16th, 2014

Picea abies ‘Nidiformis’ at Boone County Arboretum in Kentucky

Bird’s nest spruce (Picea abies ‘Nidiformis’) is a dwarf cultivar of Norway spruce and is native to northern Europe (USDA hardiness zones 3-7). This slow growing compact shrub will attain 4 feet in height and 5 to 6 feet spread over 15 – 20 years.

The shrub grows in a round form with a distinctive flat depression or “bird’s nest” cavity on top. Lush, dark green needle foliage has a medium to fine texture and deer stay away from this sharp needle conifer. Short ½ inch long needles radiate along the slightly uplifted branches.

Bird’s nest spruce grows in average acidic, well-drained soil; it is best planted in full sun to partial shade with good air circulation. In the mid-south, this shrub conifer tends to struggle during periods of extreme heat and drought. Best specimens are seen in gardens from northern Virginia and northward and through the Midwest U.S. where summers tend to be less humid and a bit cooler.

When needles appear pale or off color, feeding spruce and eriophyid mites may be the problems. Pesticide controls are very effective; also hosing down the shrub with a coarse spray of water will wash away most mites. This naturally dwarf plant rarely requires pruning, other than to remove any damaged, discolored and/or diseased twigs.

Bird’s nest spruce has year-round appeal. It is frequently included in foundation or low border plantings. It is exceptionally winter hardy and may be planted in a large container.

Extra: Picea abies ‘Maxwell’ exhibits a similar form except its top is flat but not depressed.

Growth Rates Of Four Privacy Screen Evergreens

Posted by Hugh on October 13th, 2014

Leyland Cypress Privacy Screen

In a hurry to create a little privacy from neighbors, then add a tall evergreen privacy screen to your planting chores. Four most popular conifers are rated by annual growth rate. If you recall the children tale of “The Tortoise And The Hare”, fast does not mean best.

Leyland cypress (x Cupressocyparis leylandii) (zones 6-9) has the fastest growth rate at 40-50 feet tall and 20-25 feet wide in less than 25 years. Growth rate averages 3 – 4 feet annually. Leylands are very care-free the first 10 years, except they’re suffer during long summer dry spells. Plant them 12-15 feet apart with frequent irrigation the first 2-3 years. They become too tall for their space. As shrubs age, their susceptibility to fungal diseases also increases. Pruning off dead or diseased wood is the only remedy, usually requiring working on a tall ladder. Plant spacing is 12 -16 feet apart.

Japanese Cedar (Cryptomeria japonica) (zones 5-8) is another fast grower at 30-40 feet tall and 20-25 feet wide in 30 years. Winter foliage tends to turn bronze colored, but green needle color returns in early spring. Cryptomerias may become susceptible to Cercospora leaf spot disease if shrubs are crowded too close together. Three-year and older established shrubs are very drought tolerant. Plant spacing is 12-14 feet apart.

‘Green Giant’ arborvitae (zones 5-7) is a hybrid between west coast native arborvitae (T. plicata) and Japanese arborvitae (T. standishi). Growth rate starts slow, but Green Giant gets 25-35 feet tall and 15-18 feet wide in 30 years. They are moderately drought tolerant and mostly disease and pest resistant. Plant spacing is 10-12 feet apart

Emerald® Eastern arborvitae (Thuja occidentalis ‘Smaragd’) (zones 3 -7) is slowest grower of the four, a semi-dwarf shrub with a compact, narrow pyramidal habit. Also called “Emerald Green” arborvitae, it has glossy, dark green, flat sprays of scale-like foliage. Grows 20 to 30 feet tall and 10 to 15 feet wide at maturity. Disease and insect problems are few. Plant spacing is 8-10 feet apart.

Shrubs You Should Not Prune In Fall Season

Posted by Hugh on October 10th, 2014

Flowering quince (left) and Forsythia (right)

Why would anyone prune spring flowering shrubs in the autumn season? After a long cold winter, why miss out on the delightful fragrance of lilac and viburnum flowers the following spring?

Predicting how cold, warm, or dry the coming winter season is rarely possible. Pruning cuts are wounds and weather extremes may cause injury to the previously-cut branches.

Partial list of spring flowering shrubs:
Azaleas (Rhododendron)
Beautybush (Kolkwitzia)
Deutzias
Fothergilla
Forsythias
Honeysuckles (Lonicera)
Magnolias (most deciduous types)
Mahonias
Mockorange
Flowering quince (Chaenomeles)
Spireas (Spiraea)
Lilacs (Syringa)
Viburnums
Weigela

These shrubs form their flower buds in the summer. Pruning them in the fall removes some, if not, all flower buds. Tall unruly shrubs can be partially pruned back if they spoil the appearance of your home and grounds. Expect some loss of spring blooms. You can complete the task in late spring.

Remove dead and dying branches at any time. Channel all the plant’s energy to the strongest buds and prune out weak wood. Thin out crowded and crossing branches to open up the interior of the shrub to better sunlight penetration and air circulation. This also reduces fungal diseases such as powdery mildew common to lilacs and other shrubs. Some heavy scale and adelgid infestations can be pruned off.

If a shrub is in poor health, you may want to attempt “renewal pruning”. You may opt to cut back most of shrub, leaving a few strong water sprouts around the old shrub base. Root suckers below ground can also rejuvenate an old shrub.

Storing Vegetables Outdoors Over The Winter

Posted by Hugh on October 7th, 2014

Use covered cold frame for vegetable storage in winter

In early fall before killing frost arrives, harvest of fresh vegetables is central on gardeners’ minds. You might consider storing some (not all) vegetables outdoors to take advantage of frigid winter temperatures ahead. Limited refrigerator space in your kitchen is not taken up.

Some root vegetables- namely beets, carrots, rutabagas and parsnips- are long keepers. These vegetables store best when harvested near, but not past, their maturity. To maintain safe eating quality, veggies need to be stored within a narrow temperature range between 33 and 40° F.

Carefully gather root crops without bruising or cutting the edible portions. Use a sharp knife to pare away stems and leaves. Gently wash away most of the soil from roots. Cover in damp sand or blanket with a 6 inch layer of loose (not packing) tree leaves or organic mulch.

A second option is to build your own root storage bin in a shady area near the home. Pack the vegetables into a tub, wooden box, 5-gallon bucket, or a plastic storage box (punctured with drainage holes). Start by placing several inches of moist sand on the bottom of the container. Lay a single layer of root vegetables that are not touching one another on the sand. Cover them completely with sand.

If the box is deep enough, add another layer of veggies and sand layer until box or bin is nearly full. Finish covering with a layer of moist sand. Plan accordingly as a full container may likely be too heavy to lift. When you are preparing a meal, remove stored vegetables as needed over the fall and winter months.

If you live in a cool (not frigid) winter climate, overwinter cool crops (broccoli, cauliflower, kale, cabbages, head lettuce) in a cold frame. Cover the harvested crops with a 6-12 inch layer of loose straw or leaves. No part of the green vegetable tissue should be left exposed. If covered with the glass slash, place a cloth blanket over so the sun does not heat up the cold frame. Plan to consume all veggies before the cold frame is needed to start new vegetable and flower plants in late winter.

Planting Of Norway Maple Declining In U.S.

Posted by Hugh on October 4th, 2014

Dark green foliage of Norway maple

Fine grain bark of Norway maple

Norway maple (Acer platanoides) is a hardwood tree native throughout the of Europe and widely planted in the U.S. (USDA hardiness zones 4-7a). At maturity a tree reaches 40 to 50 feet in height (to 75 to 80 feet is not unusual) and 35 to 50 feet in width. Its dense leafy canopy values it a shade tree for planting along streets, large residential properties, golf courses, and in parks.

Norway maple prefers full to partial sun and grows best in moist, well-drained soils. Established trees tolerate hot dry conditions. It transplants reliably and tolerates urban air pollution and moderately compacted soils.

Leaves are 3-5 inches long and 4-7 inches wide. The 5 palmate-lobed leaves are sharply pointed. Yellow fall leaf color is rarely stunning except in specific cultivars. Upper leaf surface is medium to dark green, and dull green, shiny, and hairless underneath.

Small yellowish green flowers appear from early to mid-spring (depending on location) and give way to 2-winged 1 ½ inch wide samaras fruits that whirligig to the ground in fall and winter.

Many cultivars are available at nurseries and garden centers. Norway maple has declined in popularity because seedlings germinate freely along roadsides and woodland areas, competing with native vegetation in the Northeast U.S.

Norway maple has few serious disease or pest problems. Tree is susceptible to verticillium wilt on dry clay soil sites. Its shallow root system frequently cracks or lifts driveways and sidewalks and competes with lawns. In northern areas, bark of young trees may be susceptible to sunscald and frost cracking over the winter months.

Cultivars:

‘Cleveland’ grows 40 to 50 feet high and a narrow 30 to 40 feet wide. Upright branching of young and middle-aged trees is ideal form for urban street planting.

‘Crimson King’ is a popular selection that grows 40 to 50 feet tall and wide; its purple-green spring/summer foliage darkens to maroon or bronze color in autumn. Cultivar tends to grow slower.

‘Emerald Queen’ is a fast-growing selection with an oval-rounded habit (50 feet high and 40 feet wide) and dark glossy green summer foliage. Bright yellow fall color is better than most.

‘Schwedleri’ grows 40-60 feet high and wide; this popular old selection renown for reddish bronze spring foliage which fades to greenish-bronze by early summer.

Tropical Looking Big Leaf Magnolia

Posted by Hugh on October 2nd, 2014

Bigleaf magnolia at Daniel Stowe Botanical Garden, Gastonia, NC

Bigleaf magnolia (Magnolia macrophylla) is native to the southeastern United States as far north to Ohio (USDA hardiness zones 5-8). A mature tree attains heights of 30 to 40 feet and develops an irregular pyramidal form. In the northern areas the tree is deciduous and semi-evergreen in the southeastern U.S.

Its enormous size foliage makes it a true horticultural oddity, something different for a residential site. Its unusual leaf size relegates planting on woodland sites where weak branches and extra large leaves are protected from ice and wind storms.

It grows in full sun or part shade and prefers a well-drained, acidic sandy loam. An established tree is moderately drought tolerant. Its large leaves decompose slowly and create a litter problem. No serious insect or disease problems bother this magnolia if properly sited.

A tree may take 10 or more years before first blooms form. Goblet-shaped flowers are creamy white, rose-purple at the petal base, and up to a foot across. They open in early summer, mostly high in the tree and mostly hidden within the dense foliage. Up close, flowers are pleasantly fragrant. Fruit is round to cone-shaped, rose-colored, and nearly 3 inches long; they’re unique, persistent, and attract numerous bird species. When cones open, each red coated seed is held by a thin silk-like thread.

Leaves are alternate, simple, 12 to 36 inches long and 7 to 12 inches wide. They’re bright green above and silvery gray below. Petioles are 2 to 4 inches long. Its yellow fall color rarely stands out. Leaves are intolerant of most urban pollutants.

It is sometimes called large-leaved cucumber tree — a reference to cucumber magnolia (M. acuminata), a deciduous magnolia from the eastern US which has cucumber-shaped fruit. Bigleaf magnolia has round or egg-shaped fruits that bear little resemblance to cucumbers.

Bigleaf magnolia may be purchased from on-line tree nurseries.