Whether you're maintaining an existing lawn or starting a new one, fall is the best time to do the ground work to ensure good results for next season.

For maintaining your lawn, the soil should be tested, and recommended amounts of lime and fertilizer should be applied. Fall is the best time to fertilize your lawn because the roots are actively growing and absorbing nutrients. This means a denser and healthier lawn better able to withstand the winter. In addition, the grass stores many nutrients in its roots, so that it is ready to produce a lush spring growth.

If you want to start a new lawn, fall is the perfect time. Most turfgrass varieties in Pennsylvania grow best in cool weather and are under stress in hot, dry weather. Grass planted in the fall has two cool seasons in which to develop a good root system and high energy reserves before the hot summer months. Also, fewer weeds grow in the fall than in the spring, so there is less competition for water and nutrients.

Many gardeners feel that spring is by far the best time to plant ornamentals. Fall is as good a time to plant in some respects, and a better time in others.

Home gardeners can directly benefit from fall planting. They often try to do so much in the spring that they can't really enjoy it. Preparing and planting a vegetable garden, and planting and maintaining their landscapes can become tiresome and cut into time which could be spent on other forms of recreation. This can be avoided by spreading the yard and garden work throughout the year.

As for the plants, fall is the best time for developing what they really need to survive roots. The roots of spring-planted trees and shrubs have to compete with developing leaves, flowers and fruits for the water and energy reserves in the plant. In the fall, there is no new top growth taking place and the existing leaves lose less water in the shorter, cooler fall days.

While the above-ground parts of the plants are going dormant, the roots are actively growing. During the fall, soil temperatures drop slowly. Roots continue to grow until the soil temperatures drops below 40 degrees. In the Lehigh Valley, this will usually be sometime in late November-early December. When spring arrives and leaves and flowers begin to grow, the root system provides all the water and nutrients needed.

Another good thing about fall planting is there is generally enough rain so that very little irrigation is needed. Newly-planted trees and shrubs should be watered during dry spells of seven days or more, but these rarely occur in the fall.

When selecting plants, many people are attracted by the flowers. Remember, plants should also be selected for their fall color. While the flowers of many trees and shrubs last a week or so, fall color can develop and hold for a period of two to four weeks. The fall color of some trees, such as red maple and sweetgum, varies considerably, ranging from yellow to red, dull to brilliant. So, if fall color is important to you, fall is the best time to buy and plant.

Fall, however, is not the time to prune and fertilize your ornamental plants. Put away the pruning clippers and the fertilizer now because trees and shrubs must harden off and mature.

Pruning or fertilizing will result in soft new growth before the cold weather sets in. Plants such as azaleas, rhododendrons, hollies and other broadleaf evergreens can be easily damaged if this soft growth is exposed to the cold weather.

The only fall pruning you should do is to remove dead, diseased or injured branches or prune out weak growth in order to develop a strong plant with a good framework. Fall is not the time to prune a shrub to improve its appearance.

Limit your fall shrub-tending activities to weeding or watering. Keep your annuals looking nice longer by picking off dead blossoms. But put away the clipper and the fertilizer if you want your plants to withstand winter weather.

For answers to your garden questions, call the Lehigh County Cooperative Extension Office, 610-391-9840, or Northampton County Cooperative Extension Office, 610-746-1970, and ask to speak with a Master Gardener. Volunteers staff phone lines several days a week, Monday - Friday.

Growing Green is contributed by Lehigh County Cooperative Extension Office Staff and Master Gardeners.