A good time to inspect houseplants for disease, damage

Succulent houseplants, such as cactuses and jade plants, are in winter dormancy and require bright light and very cool conditions with no water for up to two months. Overwatering can create soft brown patches on stems and foliage.

Monitor houseplants for insect problems that can occur when plants become stressed. New houseplants or gift plants can also harbor pests. Isolate these plants before adding them to your collection. Pests to look out for include the following:

• Spider mites: Look for webbing in leaf axils, stippled foliage and weak, off-color leaves. Mites are often difficult to see without a lens.

• Scale: Characteristic sticky, clear honeydew is produced on leaves by these small, immobile, rounded insects usually found on stems and veins of leaves.

• Mealybugs: Easy to spot, these insects resemble crowds of tiny cotton puffs.

• Whitefly: Whiteflies are a major problem in many greenhouses because they can quickly move to neighboring plants. Look for tiny, white, moth-like insects often found on the undersides of leaves.

• Fungus gnats: Adult black gnats fly around the plant but do no damage. Immature larvae in the moist soil can chew plant roots. They are often a problem in overwatered plants or in overly moist flats of seedlings.

Look outside

Continue to monitor your garden for animal damage even though there has not been much snow so far this winter. The damage to your plants may still be occurring and can be harder to see from a distance without tracks in the snow giving you a clue.

Rabbits feed on twigs and can reach higher up when there is snow for them to stand on. Deer browse on shrubs including yews and arborvitae. You may need to create physical barriers using garden netting or wire fencing to protect your plants. Repellents can be applied when temperatures are above freezing.

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