(ARA) - It may be hard to believe, but all the signs are there: The neighborhood children are back in school, dusk arrives a little earlier each day, and it is too cool to leave the house at night without a sweater or jacket. There's no denying that another summer is almost over.

Even with autumn knocking at your door, winter may still seem a long way off. However, now is the time to prepare your lawn for winter's arrival. "The most important time of year to fertilize your lawn is just before the onset of winter," said Wayne Kussow, professor of soil science at the University of Wisconsin, Madison. "Fall fertilization helps ensure that roots remain healthy and allows your lawn to store food for the winter."

In addition to fertilizing in fall while lawn plants are actively growing, experts suggest that homeowners living in northern climes fertilize again after their lawns stop growing. This second application, called dormant feeding, is really the first fertilization of spring -- just several months early.

Fall Feeding

A late summer or early fall lawn fertilization serves several purposes. It helps replenish the nutrient supply that was used up over the summer months. It also gives lawn roots a healthy start for winter dormancy. Fall feeding is recommended for Bermuda, Bahia and centipede grasses, but not for St. Augustine grass.

The key is to plan your fall feeding for when plants are still taking up nutrients for winter. While the timing may vary each year, here is a general timeline for each region:

* In the North and Northeast, the best time is usually around Labor Day.

* In the central "transition" states, begin fall feeding in August or September, as plants in this area tend to take up nutrients until early October.

* Further south, fall feeding can be done in late September or October.

Dormant Feeding

Dormant feeding is typically only done on northern turf types, such as Kentucky bluegrass, fescue and ryegrass. Even when a lawn is covered with snow or appears dead, its turf roots still may be storing nutrients for winter. Apply the usual rate of fertilizer for a dormant feeding. This equates to one pound of nitrogen per one thousand square feet, but check specific instructions on the fertilizer bag for spreader settings.

Timing the dormant application can be difficult. Watch your local weather patterns. When you see that your lawn is not growing anymore, dormant feeding is in order. Here are some general guidelines:

* In northern climates, the best time is usually after Halloween but before mid-December.

* In the transition states, plants generally go dormant after Thanksgiving.

"Golf course superintendents dormant-feed their courses every year," said Steve Bailey, retired superintendent of Brown Deer Golf Course in Wisconsin. "A dormant feeding helps prepare the greens for the stress of winter. Plus, it gives them a jumpstart in spring for early golfers."

What type of fertilizer should you use? Research conducted by Kussow at the University of Wisconsin, Madison, shows that lawns fertilized with Milorganite organic nitrogen fertilizer in the fall tend to become green in the spring seven to 10 days earlier than unfertilized lawns. Not only do Milorganite-treated lawns sustain less winter damage, they also recover more quickly from any damage that does occur. The resulting thick turf minimizes weed growth because it shades weed seedlings, preventing them from maturing. This is true from Maine to Florida to California.

Do not apply any type of fertilizer to frozen soil, as it is highly susceptible to runoff and pollutes water in lakes and streams. This not only wastes your money, but it causes environmental damage that is difficult to correct.

"Applying a fertilizer with a high amount of water insoluble nitrogen is a good way to help prevent runoff and waste," said Mike Archer, market development and research coordinator at Milorganite. "Look for an organic nitrogen source, like Milorganite 6-2-0, that is high in slow release and water insoluble forms of this nutrient."

If you are in doubt as to which fertilizer is right, start with a soil test. Contact your local county extension horticultural agent for help. Another excellent source is your local nursery.