Problem: bud drop. Solution: If buds fall off a new flowering plant you’ve just brought home, it may have been shocked by the sudden change in its growing conditions. It should recover in time. Be sure your plant isn't sitting in a draft or in a spot that’s too hot or cold. You might also want to increase the surrounding humidity.
Problem: White spots that look like powder or flour on your houseplants. Solution: This is probably a fungal disease, powdery mildew. Increase the air circulation in the room, and avoid overwatering. Saturated soils and poor ventilation are breeding grounds for this problem. Remove badly infected leaves, and if the problem persists, look for an organic fungicide labeled safe for indoor use. Follow all label directions. Shown here: a vining Philodendron, 'Brasil'
Problem: Bumps on plant leaves and stems. Solution: Scale, insects with hard shells, often infest houseplants; a sooty, black mold can signal their presence. Try scraping them off with your fingernail or the edge of a butter knife. If your plant is badly infested, or the problem persists, try “spot-treating” by touching the scale with a cotton ball dipped in rubbing alcohol. If that doesn’t work, step up to a product labeled for scale.
Problem: Small, winged insects are feeding on your houseplants. Solution: Thrips are at work, leaving black speckles and distorting plant parts. You may also see stippled leaves or flowers that die before opening. Control thrips with an insecticidal soap or neem oil and follow package directions.
Problem: Mushy or blackened stems. Solution: Cut back on watering. Houseplants usually need just enough to keep the soil moist, not wet. Be sure to empty the saucers under your plants after you water, too, so their roots don’t stand in water and start to rot. This Sanservia, 'Black Robusta', needs very little water and even thrives on neglect.
Problem: White, cottony spots or masses show up on foliage. Solution: Mealybugs are sucking the juices from from your houseplants. Try knocking them off with a gentle spray of water from the kitchen sink (or shower, if you have big potted plants). If they return, apply an insecticidal soap or neem oil. Always follow the product directions.
Problem: You see webs on your houseplants. The leaves look discolored and/or curl and drop off. Hard-to-see spider mites, which are actually spiders, are the likely cause. Solution: Knock the mites off with a gentle spray of water from the kitchen sink, or put big plants in the shower. If the pests keep coming back, use an insecticidal soap or neem oil. Shown here: Dracenea 'Song of India'
Problem: Swarms or clouds of tiny white creatures fly into the air when you move your plants. Solution: You’ve got whiteflies, insects related to aphids that suck plant juices. They make a sticky substance called honeydew that can attract fungal diseases. Spray the plant with an insecticidal soap, following label directions. You’ll probably need to re-treat. Some gardeners use a homemade spray of 2 parts rubbing alcohol, 5 parts water and one tablespoon of mild liquid soap. The good news is that some houseplants, like this red Anthurium, are seldom troubled by these pests.