| Problem | Description | Controls | |
Aphids
| Often called plant lice, these insects are up to 1/8 inch long and may be green, red, black, or brown. Tender new growth and leaf undersides are usually affected. Aphids suck the plant juices causing yellow foliage and death. They secrete a sticky "honeydew" that is deposited on leaf surfaces.
| Minor infestations can be treated by spraying or showering with water. Severe infestations will need treatment with an insecticide safe for houseplants.
See Insect Problems. |
Brown leaf tips
| Look for leaf edges that turn crispy and brown as if burned. New growth is often affected, becoming brown and weak. Culprits are: too high heat, too low humidity, allowing plants to dry out between watering, cold or hot or dry drafts, or over-fertilizing.
| You must correct the problem causing the browning, so: lower the temperature, raise the humidity, stop the drafts, water more evenly, and carefully follow fertilizer directions. Note: some houseplants are sensitive to fluorides or other chemicals in water. Simply trim off the browned leaf tips.
|
Bud drop
| Flower buds drop off before flowering. Causes are varied: too high room temperatures, too low humidity, hot or cold or dry drafts, uneven or insufficient watering, too much fertilizer, or shock from being moved while in the bud stage.
| Determine the problem and correct it. Lower the heat, increase the humidity. eliminate drafts, water evenly, and don't move the plant to new locations frivolously. |
Failure of plant to bloom
| Flowering plants don't flower. Main reasons are: insufficient light or too much high-nitrogen fertilizer. Some blooming houseplants like poinsettias and Christmas or Easter cacti are dependent on day length and must be shaded. See Holiday Houseplants for information.
| Position plants in bright light - use supplemental grow lights for 14+ hours daily. Use only a low nitrogen fertilizer. Mist daily to raise humidity high and keep soil moisture constant. Follow re-blooming instructions for plants that are sensitive to day length.
|
| Fungus Gnats | Clouds of tiny black flies - smaller than fruit flies - swarm around plants and on the soil surface. They suck the plant juices damaging foliage and weakening the plant. They reproduce quickly and will kill the plant if left untreated. | Repeated applications of a houseplant insecticide are required to eliminate fungus gnats. You will have to treat the soil surface too. Adding a 1/4" layer of sand to the soil surface helps discourage them. Don't handle other plants that are not infected to prevent spreading.
See Insect Problems.
|
Mealybugs
| Mealybugs are soft-bodied, 1/4-inch-long insects with a powdery coating of white or beige. They look like little cotton balls clustered under leaves or on shaded ones, or in stem crotches. They suck plant juices and can severely weaken or kill plants.
| Good results can be had by daubing each insect with rubbing alcohol. Use a cotton swab to apply. For severe infestations, use repeated applications of a houseplant insecticide.
See Insect Problems. |
Scales
| Scale insects are oval or round, 1/8 inch long, and have a shell-like covering. They come in brown, black, gray, or white. Scales leave a honeydew residue on leaves that is sticky and/or shiny. They suck plant juices and can weaken and kill plants.
| For small infestations, remove them with soapy water. Serious infestations will need repeat applications of a houseplant insecticide.
See Insect Problems. |
Spider mites
| Spider mites are so tiny they can barely be seen. You will notice yellow flecks or speckling on the upper side of the leaves, an overall dull look to the foliage, and fine webbing in severe infestations.
| Proper watering and high humidity are the best preventatives. Shower plants weekly with plain, lukewarm water. For severe infestations, use a houseplant pesticide that specifies it is effective again spider mites.
See Insect Problems.
|
Whiteflies
| These white insects rise in clouds off disturbed plants and look like flying dandruff. They suck plant juices, yellowing foliage and weakening plants. They reproduce quickly and will kill the plant if left untreated.
| Repeated applications of a houseplant insecticide are required to eliminate whiteflies. Don't handle other plants that are not infected to prevent spreading.
See Insect Problems.
|
Wilt
| This can quickly kill a plant. The main causes are: insufficient water, poor soil, high temperature, low humidity. Water-logged or poorly drained soil can also rot plant roots causing wilt.
| Correct the problem: lower temperature, water more often and more evenly, raise the humidity, repot the plant or top dress with fresh soil. Improve drainage and avoid overwatering or watering too often.
|
Yellowing foliage
| Yellowing foliage that falls off can be caused by different problems: too much/too little light, high room temperature, overwatering, poor drainage, too much or too little fertilizer - or the wrong type, air pollution. Some yellowing and leaf drop of older leaves is normal.
| Correct the problems that are causing the condition. Provide the correct amount of light, lower room temperatures and raise humidity, water evenly, fertilize correctly with the right fertilizer for the plant, and ensure good air circulation and fresh air. |
Dust covering leaves reduces the plant’s ability to produce its own food. Keep the leaves clean for a healthier, better looking plant. Glossy leafed plants can be dusted with a soft cloth, dampened with milk. Rub gently to remove spots and add a nice shine.
Don’t rub hairy leafed plants like African violets and gloxinias. Instead, rinse their leaves with warm, room temperature water from a spray bottle or use a soft artist's brush to remove dust..
If only a small portion of a leaf is damaged, remove this section only. If half or more is damaged, remove the entire leaf. This makes the plant look better and prevents the spread of disease. Use clean, sharp scissors or a knife.
The correct 
Houseplants grow better when fertilized properly. Use a slow release or water-soluble fertilizer and follow the directions. During low light periods from late fall through winter, reduce the fertilizer rate by half. Resume normal fertilization in early spring through summer.
Every year or so plants benefit from 
Proper watering of houseplants is critical to avoid the majority of pre-mature deaths. Most houseplants are from the tropics so, they need room temperature water. Using cold water can stunt the growth of the plants and damage the foliage.
The plant will tell you when it needs to be watered. The first sign is when the foliage takes on an off-green color. In more extreme cases, the youngest growth starts to flag or wilt. Water as soon as you see the first signs of wilting.
It is usually easiest and best to water the plants from the top. Apply warm water gently stream of water so as not to wash out the soil. Don't get water on the leaves because this can cause leaf spotting.
Some plants, like African violets prefer to be watered from below. Fill the plant’s tray with a little water and let it sit for 20 -30 minutes. Remove any water that is not absorbed
When you water, drench the soil. Make sure the plant is in a container with a hole in the bottom so that excess water can flow out. Empty the excess water. Leaving your plant sitting in water will make it susceptible to root disease.
When the soil has been allowed to dry out too much, it is difficult to wet it again. It is best to take the potted plant and put it in a sink filled with several inches of warm water. Let it sit there for several hours until the water is absorbed into the soil mass.
Watering will vary. If the plant is growing in a clay pot it'll have to be watered about twice as often as in plastic pots. If the room has low humidity or the plant is pot-bound, it will have to be watered more. 
Fill the tray the plant is sitting in with gravel or marbles and water to raise the humidity around the plant.
Fill the larger pot about half way with soil, and mound it up against the sides a little.
Water the plant thoroughly and remove it from its pot. Gently loosen any tightly bound roots and prune off any overlong or damaged roots. Dust with an all purpose bulb dust.
Place the plant in the new pot and fill with soil, pressing the soil down as you go to avoid air pockets. Leave about 1/2 to 1 inch between the soil surface and the top of pot. Water thoroughly.