Prepare your garden for autumn

The hot days of summer are the perfect time to prepare your vegetable garden for the cool days of autumn.

During the first week of August, plant crops for fall harvesting, such as short-season snap beans, broccoli, cabbages, cauliflower, carrots, mustard greens, spinach and radishes.

Continue to harvest herbs. You can snip up the leaves to use right away or store them by drying entire sprigs or plants or by freezing individual portions in ice-cube trays.

Pinch off developing flowers to retain essential oils and flavor in the herb plants' foliage.

If the plants growing in your containers or baskets are looking stunted or have leaves that are yellowing, then they may need supplemental fertilizer. The frequent watering required for containers and baskets can leach nutrients out of the growing medium. Use a liquid fertilizer as needed to perk them up.

It is best to fertilize plants in containers and baskets when their soil is moist. Fertilizing plants that are very dry can result in damage to their roots.

Don't automatically use an insecticide if you see insects on your plants. First identify the insect and determine if it is really a problem. Most insects are harmless, and some are beneficial, helping to control harmful insects naturally.

If you have identified an insect as one that harms plants, try to assess if the damage being done warrants control or is slight and insignificant.

If you decide that an identified pest is causing significant damage, it is important to use a correct control with proper timing. If a variety of treatments are available, use the least toxic one.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.