Trees and Shrubs March Reminders
Trees and Shrubs in the March Garden
* The 1992 All America Selections winner, Tropical Rose, is a canna that blooms from seed in about 100 to 130 days. Plants flower at 1 to 2 feet and mature over the summer to bushy, 2-foot plants. It can be used as a bedding plant or in containers.
* A good rule of thumb for planting rhododendrons is: the smaller the leaf (i.e., R. carolinianum, R. laetivirens), the more tolerant it is of winter sunlight. Large-leaved rhododendrons, such as R. catawbiense or R. maximum, have more winter injury when planted in bright locations.
* To protect seedlings from cutworms, cut newspaper into three-inch squares. Wrap a square around each plant's stem. About half the "collar" should protrude above the ground when the seedling is planted.
* When transplanting a young shade tree, it may help to orient the tree in its new location the same way it was in its old home. This will prevent previously shaded bark from suddenly being exposed to afternoon sun and causing injury. When not possible or desirable, or if the original orientation is unknown, wrap the trunk in tree tape or coat the sunny sides with white, exterior, latex paint for one growing season.
* Be aware that a brown plastic material that looks and feels like natural burlap, but does not break down in the soil, is now being used to wrap root balls of balled and burlapped plants. Synthetic materials enclosing the roots of trees and shrubs must be completely removed to ensure success of the transplants. Nurserymen have being alerted to avoid using brown plastic burlap, but there are still some landscaping plants on the market with soil balls wrapped in brown plastic. If you purchase balled and burlapped plants, to be on the safe side, remove the material covering the soil. If the tree is very heavy, peel the burlap down to the bottom of the hole if you cannot remove it completely.
* Some towns and cities are repeatedly bothered by inexperienced people selling trees or shrubs that have been dug from pastures or forests. Such plants usually have poor survival rates due to small, shallow, root systems that may have been damaged when dug or stored improperly. The best trees and shrubs are those grown in a nursery where a deep, full, root system develops. When these are carefully dug and the roots kept moist, the plants should recover quickly after transplanting.
* If you are buying bare-root trees, look for ones with a large root system in relation to the top growth. It is not necessary to purchase a very, large tree to get a quality plant.
* Potted azaleas, available through May, will flower for two to three weeks, if the soil is kept slightly moist. Display in a cool (60° F), bright location, and remove withered flowers. Unless you have room to experiment, discard when blooms fade since most florist azaleas are not hardy enough to be established outdoors.
* Young trees can be inexpensively protected from rodents, string trimmers and mowers with short, plastic, tube-shaped, tree guards. Each protector should be 9 to 10 inches tall and long enough to wrap around the entire trunk base. At least one company sells trimmer guards for trees, but gardeners can cut other plastic tree protectors to size for this purpose.
* Trees and shrubs with weak growth may need to be fertilized to stimulate more attractive development.
* Research has shown that young trees allowed to move with the wind develop greater trunk strength than trees rigidly staked.
* Plant roses and bare-root shrubs while they are still dormant, about four weeks before the average date of the last frost.
* Crabapples, valued for their beautiful spring blossoms and attractive fruit, are members of the rose family. Along with their relatives, many crabapples are susceptible to diseases, such as scab, cedar-apple rust, powdery mildew and fire blight. All of these diseases shorten the life span of the trees and diminish their ornamental qualities. Plant disease-resistant cultivars of crabapple, such as 'Ames White,' 'Autumn Glory,' 'Baskatong,' 'Beauty,' 'Coral Cascade,' 'Evelyn,' 'Harvest Gold,' 'Molten Lava,' 'Red Snow,' 'Robinson,' 'Tina' or 'Wies.'
* Dogwoods and magnolias should only be moved in early spring. Always move magnolias with a ball of dirt.
* Propagate deciduous shrubs, such as forsythia and winterjasmine, now by ground layering.
* When transplanting dogwoods, it is best that the trees be small (2 to 3 feet tall) and dormant. These do better than larger ones. The larger the tree, the greater the risk of death due to transplant shock since more roots are removed during digging.
* Boxwoods may be moved now; do not plant them deeper than they were previously planted. Trim and fertilize established boxwoods before new growth starts, but do not cultivate under boxwoods since their roots are shallow and may be damaged.
* Some insect pests of trees and shrubs are best controlled by spraying with dormant oil. This includes scale insects of pine, lilac and euonymus and many of the gall-forming insects. These insects reside on stems or needles and are smothered by the oil.
* Galls are mostly a cosmetic problem, but scales can weaken plants. Check weather forecasts to be sure temperatures will stay above freezing for eight to 12 hours after spraying to avoid damaging stems and needles.
* Be sure to employ properly trained tree trimmers. Pruning is not a particularly difficult job. However, it does require an understanding of the growth habit of the plants and the form needed to secure the desired landscape effect.
* Once new growth begins on trees and shrubs, cut back winter-killed twigs to living, green wood.
* For more compact pyracanthas without the risk of losing berries, pinch back new growth now.
* Prune evergreens and evergreen shrubs for shape and size before growth starts, as early in the month as possible
* Boxwood should be pruned by thinning the outer foliage of the plant and cutting back the branches to retain desired height.
* Prune spring-flowering shrubs after flowering is completed.
* Hedges can receive their first pruning this month. As you prune, be sure to leave the base of the plant wider than the top. This allows sunlight to get to the bottom of the plant, creating a full, dense hedge.
* Don't leave stubs when pruning; stubs usually die and are entry points for decay fungus. Cut just outside the branch collar, the slightly thickened area at the base of the branch. Pruning should never be done in damp or wet weather when the fungal spores and bacteria that infect plants through fresh wounds spread easily.
* Trees that bleed, such as birch and maple, should not be pruned until after their leaves are fully developed. Elm, maple, birch and black walnut trees ooze sap when pruned in the spring due to water pressure from the moist soil. It will not harm the plant, but you can prune these in early summer or late fall instead if you are bothered by it.
* After pussy willow catkins have passed their prime, prune the plants drastically to encourage long branches and large catkins for next year.
* Plant new rose bushes in properly dug beds. Fertilize established roses after pruning. It is wise to have your soil tested about every two years. If black spot or powdery mildew has been a problem, start applications of a recommended fungicide. Contact your local Extension agent for current recommendations.
* When pruning or cutting roses, cut all flower stems 1/4 inch above a complete (5 leaflet) leaf, leaving two complete leaves below the cut bud. Always use sharp, pruning shears and cut on a slant.
* Complete the pruning of shrubs and ornamental trees before new growth starts, except for spring-flowering shrubs. Prune those in the spring after they finish flowering.
* For good drainage in tight clay, plant trees on the "high side" by building up the area around the root ball or by laying drain tile from the bottom of the hole to a ditch or to a special drainage area. Provide a drainage area by digging another hole lower than the planting hole and filling it with gravel. Use pipe or tile to carry excess water to this hole from the tree roots. Another solution is to play it safe and select a tree that withstands "wet feet."
* The end of the dormant season is the best time to prune almost all trees and shrubs. Pines are about the only exception. Let their new growth expand until young needles are half of full size before pruning. Spring flowering shrubs can be pruned now, too, unless you can't stand losing the flower buds on the stems you're removing.
* Branches cut from spring-flowering shrubs and fruit trees can be brought in and put in warm water to force them into bloom.
* Do not use tree wound dressing or paint on pruning cuts. These can slow the healing process.
* Prune out and burn or bury the brown, shriveled "witches-brooms" on honeysuckle. The leaf-folding aphid that causes these overwinters in these growths. They feed on new growth as soon as the buds break in the spring. This one is hard to control, because untreated honeysuckles are everywhere. This may be a good time to consider replacing honeysuckles with less invasive plants that have fewer pest problems.
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