How to keep your containers healthy looking

If the plants growing in your containers or baskets are looking stunted or have leaves that are yellowing, they may need supplemental fertilizer. The frequent watering required for containers and baskets can cause nutrients to leach out of the growing medium.

Use a liquid fertilizer as needed to perk them up. It is best to fertilize the containers and baskets when the plants are moist. Fertilizing plants that are very dry can result in damage to the plants' roots.

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

Continue to harvest herbs by either snipping foliage, drying entire sprigs or plants, or freezing individual portions in ice-cube trays. Pinch off developing flowers to retain essential oils and flavor in the plants' foliage.

• Japanese beetles are showing up in gardens now and will be active for the next four to six weeks. They are easy to spot in the garden, with their iridescent copper and green colors and a preference for plants in the rose family.

Control them by simply picking them off your shrubs and squishing them or flicking them off into soapy water. Spraying with an insecticide is not usually necessary.

• It is important to identify the insects on your plants before treating with an insecticide to determine whether or not the insect really is a problem. If it is, try to assess whether the damage being done warrants control.

The presence of insects feeding on the plants should not warrant automatic treatment. Some insects are beneficial and help control other insects naturally.

If 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 control possible.

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