Keeping plants well groomed requires removing dead and dying plants and leaves. It also requires weeding, applying mulch, and pruning plants to maintain size or to remove crossed or dead branches. You can take care of many of these activities when you walk through your landscape to enjoy its beauty and observe changes. Perform them regularly through the season to avoid having to do too much all at once.
Weeds are plants that grow where they are not wanted. They compete with desired plants for water, nutrients, and sunlight. They also may harbor diseases and pests. Weed species can thrive even in poor soils. They can be spread by seeds or by underground stems called rhizomes. Remove weeds as soon as you see them. This is particularly important in an area planted with ground covers or perennials. If weeds spread in one of these areas, it is very difficult to get rid of them without redoing the bed.
You can reduce weed infestations by preparing the soil well initially. Remove all weeds and weed roots before you plant. Before planting new perennials, be certain there are no weeds growing among them in the containers. After planting, apply a three-inch layer of organic mulch to help prevent new weeds from growing. Make sure the mulch does not touch the trunk or main stem of the plants.
Hand-pull weeds near established plants before the weeds flower and produce seed. Herbicides can be useful in managing persistent weeds. Some will kill weeds selectively without harming ornamental plants. Others kill all plants either by contact with the foliage or through the root system. If you are considering using a herbicide, carefully read and follow all label directions. Be sure that you select the product intended for the weeds you want to control and use it properly so that you do not injure your ornamental plants.
Remove Plant Debris
During the growing season, rake and remove excess leaves, twigs, spent blossoms, fruit, or seed capsules that have fallen from your trees and shrubs. Rake leaves in the fall and properly compost them. This "cleaning" is important because some harmful insects and diseases can survive the winter in this debris. By removing the debris, you can eliminate a source of problems for next year.
Remove Dead Plants
If a shrub or tree dies, try to determine what caused it to die and remove the plant from the area. Burn it or throw it away; do not add it to your compost pile. It may contain a disease or an insect that could spread to other plants. In most cases, do not replace the dead plant with the same type of plant. It is likely that whatever condition caused the first plant to die still will be present and also will cause the new plant to die. If you can identify the cause of plant death, replace the plant with a species that is resistant to the problem, or that is better suited to the conditions at the site.
Remove Spent Blossoms
Most shrubs can benefit from having dead blossoms removed. By removing them, you redirect the plant's energy that would have gone into seed production into producing new, healthy growth. You can gently pull off the spent blossoms or, if you planned to prune that shrub anyway, do so right after the plant blooms. On plants that produce ornamental fruit, you probably will want to leave the flowers alone, so they can mature and produce the fruit crop.
Remove Overcrowded Plants
As shrubs and trees reach maturity, it often becomes obvious that they were planted too close together or too close to the house. Plants need adequate space to allow for airflow through the canopy and to reduce shading. Identify the plants in your landscape and learn what their mature size will be. If plants are too large or overcrowded, the easiest remedy may be to remove them and install smaller plants. Or, it may be more practical to remove one or two of the plants to make room for others.
Prune Plants as Needed
Pruning is cutting a plant to shape it, to maintain its health, or to improve the quality of its fruit or foliage. If you want to keep your plants at a specific size, it is best to prune them each year rather than having to cut them back severely after they have become too large. Proper pruning should start when you plant a shrub or tree and should be a regular part of maintaining a landscape. Always prune to retain the natural shape of the plant to give it the best opportunity for optimum health. Do not use a technique called "topping," which involves cutting back all branches or stems to the same level. Topping can shock a tree and lead to its decline and death. Multi-stemmed shrubs often become dense and will benefit from thinning. Thinning means cutting off older, thicker stems near ground level and/or cutting branches back to a larger branch. Properly thinned plants also will retain their natural shape.
Follow these general principles of pruning:
- Remove dead, diseased, or damaged wood as well as branches that cross each other.
- Remove "nuisance" growth: branches that are likely to interfere with power lines or the space above sidewalks, or that may block views.
- Make pruning cuts just above a bud and at a slight angle. To encourage a more open form, be sure that a remaining bud is located on the outside of the stem. If you cut above a bud that is growing on the inside, the new growth will be toward the inside of the plant, resulting in unwanted crossed branches.
Another type of trimming, called shearing, is used to keep plants in a formal shape, often for hedges. It is done when the plant is growing most actively, because the growth is soft and easiest to cut, and because cutting at that time stimulates new growth from buds along the stem. This specialized trimming is appropriate only for a few specific plants and must be done correctly.
Some commonly used plants that may be sheared are boxwood, yew, privet, and hemlock.
You often will see hedges sheared to have a flat top and vertical sides. This shape seldom is successful because snow accumulation on the top breaks branches, and the lower branches that do not receive sufficient sunlight often die, leaving bare gaps. The best shape is a rounded or slightly pointed top with sides slanting to a base that is wider than the top.
Each group of plants--young shade trees, mature shade trees, needled and broadleaf evergreens, deciduous multi-stemmed shrubs, and ground covers--requires a specific technique.
Because pruning technique varies for each plant group, obtain a good basic guide to pruning. Special Circular 235, "Pruning Ornamental Plants," is available from your local Penn State Extension office.
Use Proper Pruning Tools
For large-scale pruning operations, it often is best to hire a professional arborist who has the required expertise, tools, and insurance.
To perform routine small-scale pruning in your landscape, you will need to have the right tools including hand pruners, pruners with long handles (called "loppers"), a pruning saw, and a pole pruner for tall trees and shrubs. Choose bypass-style tools that cut cleanly, rather than the anvil type that tend to crush plant stems. Good quality loppers can be used to cut limbs up to 3/4-inch in diameter. Above that size, it is best to use a pruning saw. For shearing, you can select long-handled hedge shears or electric shears. If you have to prune out diseased parts of a shrub or tree, disinfect your tools before making more cuts to avoid spreading the disease. To do this, use a solution of one part bleach in nine parts water, or dip the tool in rubbing alcohol. Always clean and dry the tools before putting them away.
Sharpen pruning blades with a stone and rub them with light oil before putting them away for the winter.
For More Information
Penn State Extension, Delaware Cooperative Extension, and the Southeast Pennsylvania IPM Research Group have been working together to provide information and educational materials on IPM and landscaping.
The Southeast Pennsylvania IPM Research Group is a collaboration of university and industry horticulture professionals who are inspecting landscapes across the region to monitor pest populations and share current IPM data. The group is partially supported by the Pennsylvania IPM Program (PAIPM). For more information about the research group, contact: Penn State Extension, Montgomery County, 1015 Bridge Road, Suite H, Collegeville, PA 19426-1179; telephone: 610-489-4315.
Prepared by: Stevie Daniels, Penn State master gardener, Gregory Hoover, extension entomologist, Larry Kuhns, professor of horticulture, Gary Moorman, professor of plant pathology, Robert Nuss, professor of horticulture, David Suchanic, Penn State Extension educator, and Emelie Swackhamer, Penn State Extension educator. Title illustration by Mary Thompson.