Fall is in the air.

Mornings are cooler and crisper, and days are shorter. Soon, trees and shrubs will change color and drop their leaves.

Plant growth begins to slow this month and more energy is diverted into plant roots as they prepare for winter. Make the most of the pleasant cooler weeks ahead because time spent in the garden this month is almost as important as work done in a spring garden.

Fall cleanup not only makes a garden look better, but can dramatically reduce pesky disease problems next season. Remove all weeds, diseased plants and debris from in and around plant beds. These can harbor viruses, fungi and bacterial pores.

Dig the weeds out completely. Weeds are generally tough plants that can grow under difficult conditions. Some have large tap roots that will re-sprout in spring if they are left in the ground, stealing food and nutrients from next year’s spring plantings.

Prune dead limbs, disease, cankers or areas of mechanical damage from perennials and shrubs.

Between prunings, disinfect tools with a 70 percent bleach and water solution, says Holly Thornton, a plant disease diagnostician for the University of Georgia. This will help prevent contamination. Never compost diseased material. Bag it and throw it in the trash.

This is not the time to do any major pruning. Spring-flowering trees and shrubs have already set next spring’s flower buds, and the best time to prune them is immediately after flowering has stopped. Pruning encourages tender new growth, which is more susceptible to damage from winter wind and temperatures. Wait until late February or early March for major pruning activities.

There is no better time to plant trees and shrubs than in the fall. The soil is still warm enough to encourage root development, the temperature is cooler and winter rains will soon be in the forecast. Fall tree and shrub plantings have a much better chance of becoming established before they have to face the stress of heat next summer. Wait until spring to fertilize unless a soil test shows deficiencies of potassium or phosphorous.

Winter weeds will soon start coming up in lawns as nighttime temperatures drop to between 55 and 60 degrees. Pre-emergent herbicide can be placed over the top of the grass now to stop them from sprouting. It is so much easier to prevent them than to eradicate them after they emerge. Low nitrogen lawn winterizer is helpful if applied now.

Plant cool season annuals and perennials in mid- to late October. Refresh beds with compost and other organic material prior to planting. Pansy, viola, snapdragon, diascia, nemesia, calendula, lobelia and dianthus are excellent choices for dramatic fall color in beds and container plantings. Light frosts will not damage any of these if they are planted in well-drained soil and full sun.

Get the most from mass plantings in strategic spots near a front door or patio. Snapdragons need some extra protection if temperatures drop suddenly below freezing as do their cousins, nemesia and diascia. Diascia are growing in popularity due to their long flowering season lasting from early fall into midsummer. Potted chrysanthemums can also add color inside or out and can be planted in the garden after blooming for future fall color.

Spring flowering bulbs are available in nurseries now for fall planting. Early and midseason blooming varieties do best in our area, and they should be planted a little shallower than what is recommended for northern gardeners. None should be deeper than a couple of inches, according to Mississippi State University horticulturist Donna Beliech.

Tulips need 10 weeks to 12 weeks of chilling prior to planting, and hyacinths need about eight. Both should be treated as annuals in our growing zone. Massed plantings of 50 or more bulbs in a single color make the most effective plantings in a landscape.

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Miriam Jabour, a Master Gardener and Master Flower Show judge, has been active in the Openwood Plantation Garden Club for over 35 years. Write to her at 1114 Windy Lake Drive, Vicksburg, MS 39183.