Keep flowering baskets healthy with supplemental fertilizer

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 the containers and baskets when the plants are moist and not dry. Fertilizing plants that are very dry can result in damage to the plants' roots.

Annuals that require or prefer full sun will often stop flowering if in too much shade. Even shade-loving flowers will have reduced flowering if growing in too much shade. Annuals that are over fertilized will generally be oversized with lots of green foliage and very few flowers.

Pay careful attention to watering your containers during hot periods. The plants have been growing for some time and can quickly dry out and become damaged by getting too dry.

• If the new growth at the tips of your pine's branches has turned brown, a disease called diplodia tip blight may be the problem. It is too late to spray fungicides now as infection occurs in the spring. Prune out dead tips in dry weather to reduce the spread of infection. Disinfect pruners in between plants when pruning out diseased branches. I use Lysol disinfectant.

• 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, then 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.