Whenever you bring home a new houseplant baby, keep it isolated for a week or two to watch for pests. This keeps your others from getting an infection, because pests just love new hosts.

Give your houseplant the amount of light it needs. That's harder in the winter, but you can supplement with grow lights. A strong plant resists disease.

Wash your smooth-leafed plants regularly with plain water to remove dust. Bigger plants will do nicely with being wiped off with a soft, damp cloth to keep the dust down. If you feel you must wash the plants with soap, use mild dishwashing liquid very highly diluted.

Never dust plants with a feather duster. Always rinse any cloth you're using before proceeding to the next plant, to prevent spreading pests.

Check each plant every time you water. Look at the undersides of the leaves and check the pot for evidence of pests or mold.

If you find any pests, try these non-chemical pest controls first.

• Wash with a mild detergent solution (1/2 teaspoon per quart of lukewarm water). Turn small plants upside down in the sink and swish around. (Put foil over the dirt first!)
  
• Wipe away aphids, mealybugs, scales or mites with a soft cloth dipped in this mild solution.
  
• Try a spray of water to dislodge insects, but watch that you don't spread them to other plants.
• Pick the pests off one by one.
• Put a sticky trap over your plants if you've got whiteflies, fungus gnats, winged aphids, or thrips.
• Prune away infested branches and leaves. Throw those trimmings right outside into the snow to keep them from spreading disease!
  

For a serious infestation, cut the plant back down to the soil. Repot if necessary. Keep it lightly watered with a mild fertilizer and watch for new sprouts. It could happen!