Houseplants can be confounding. Some seem to thrive no matter what the conditions, while a few seem to need exactly the right pot in just the right window with just the right filtering, just the right watering (don’t get the leaves wet!), and just the right fertilizer on exactly the right schedule.
When a plant is sick, it sometimes takes a bit of sleuthing to figure out what the problem is. And there might be more than one problem! Here’s a list of symptoms and possible problems to help you with your detective work — as well as solutions to help you nurse your plant back to health. Be patient and willing to try a few things. A recovering plant is worth the effort!
Note: If you discover insects on your houseplant, consult a good resource for identification and remedies. A good source for natural methods is Houseplant Pest Control by Amy Andrychowicz.
Symptom: Spindly plant (long, reaching stems)
Possible problem:
Not enough light
Solutions:
• Move your plant to a window where it will get more light — but make it filtered light (through a sheer curtain, for example), at least until you make sure it won’t burn.
• Cut back the long stems (using clean plant scissors, cut right above a leaf on the stem) to encourage branching.
Symptom: Wilting
Possible problem:
Soil is too wet or too dry
Root rot
Too much salt in water
Too much fertilizer
Bound roots
Solutions:
• Water the plant deeply but less frequently. Watering well (until the water runs through the pot) will help flush salt from the water. Wait until the soil dries out about an inch deep (to your first knuckle) between waterings.
• Cut back on fertilizing.
• Repot if plant is rootbound. Also repot in fresh, sterile soil if the soil is soggy and doesn’t dry out.
Symptom: Weak, stunted growth
Possible problem:
Wet soil
Dehydration
Poor lighting
Bound roots
Virus
Nutritional deficiency — If a plant is lacking phosphorus, its leaves may be dark green. If it’s short of potassium (K), the leaves may become yellow with dark spots. If the plant isn’t growing and the leaves are pale green-yellow, it may need more nitrogen (N).
Mealybugs — These visible bugs leave a white cottony substance on the stems, nodes, and undersides of leaves.
Aphids — These tiny black, brown, or green insects live on the undersides of the leaves.
Solutions:
• Make sure the plant doesn’t have insects. (If it does, treat for the specific culprit.)
• If the plant is rootbound (you can see the roots coming out the drainage hole in the bottom, or the soil dries out quickly, or the roots are pushing the plant up out of the planter), repot it in well-drained soil with high organic compost content.
• Cut back on watering. If the soil remains soggy, repot the plant with well-draining soil. Going forward, water well, then let soil dry out about an inch down (as far as your first knuckle) before rewatering.
• Fertilize regularly (once a month through the spring and summer months) with a balanced houseplant fertilizer.
• Experiment with the lighting. Move your plant to a sunnier location, with filtered sunlight.
Symptom: Rotting, wilting roots and stems. Will appear brown or black and soft.
Possible problem:
Root and stem rot
Disease
If your cactus is rotting, it may be because you are watering over the top of the plant rather than on the soil around it.
Solutions:
• Remove any remaining water from the top of the plant (dab with a towel or tip the plant).
• Repot the plant in sterile potting mix using a clean pot and removing infected (dark, mushy) roots.
• Don’t overwater. Allow soil to dry about an inch down (to your first knuckle) between waterings.
• Provide good drainage.
• Treat specific disease as necessary.
Symptom: Rotting and molding in terrariums, condensation on sides of terrarium
Possible problem:
Overwatering
Solutions:
• If there’s a lid on the terrarium, remove it until some of the moisture has dissipated.
• Gently wipe any excess moisture from the inside of the terrarium, if possible.
• Put a strip of paper towel over the edge of the terrarium, half in and half out. The towel will absorb some of the moisture. (Remove when it becomes saturated, and replace if needed.)
• If the soil remains stubbornly soggy, replant your terrarium plants with fresh, sterile new soil.
• Cut back on watering. Here are some good directions for watering (and otherwise caring for) a terrarium.
Symptom: Yellowing leaves
Possible problem:
Not enough light
Overwatering/poor soil drainage
Low humidity
Cool temperatures
Drafty location
Pot-bound roots
Not enough fertilizer
Insects (like whitefly, a small, white, gnat-like insect or mites)
Disease (anthracnose can turn leaves yellow, then brown)
Nutritional deficiency — If lower leaves turn yellow or brown, suspect iron or nitrogen deficiency.
Solutions:
• Inspect plant for disease or insects. Treat as necessary.
• Remove infected leaves.
• Move the plant to a sunnier location. Try bright, filtered sunlight.
• Increase humidity, but don’t mist the plant. Instead, place it on a tray of pebbles and fill the tray with water. Or put it in a room with better humidity (or a humidifier).
• Make sure the plant is not in a drafty location (near a door, fan, air conditioner, or drafty window, for example). Move it to a warmer location, if possible.
• If the pot doesn’t have good drainage, or the soil seems soggy, or the plant is root-bound, repot in new, well-draining soil.
• Increase air circulation by allowing plenty of space between plants.
• Fertilize once a month during the spring and summer months with a balanced houseplant fertilizer.
Symptom: Dropping leaves
Possible problem:
Poor light
Extreme temperatures
Overwatering
Underwatering
Bound roots
Low humidity
Insects
Disease
Solutions:
• Look for insects or disease and treat accordingly.
• Experiment with increased light. Bright, filtered light is usually best.
• Make sure plant isn’t in a draft, or near a too-cold window.
• Repot if root bound (the roots are growing through the drainage hole or pushing the plant up out of the pot, or causing the soil to dry out too quickly).
• Mist plants or set on a shallow tray of pebbles and put water in the tray.
• Let soil dry about an inch down between waterings (to your first knuckle), then water thoroughly (until the water runs through the drainage hole).
Symptom: Spotty leaves
Possible problem:
Fungus — spots that are brown with a yellow halo
Bacteria — also spots that have a yellow halo but look water soaked
Solutions:
• Remove damaged leaves.
• Keep the diseased plant away from other plants, to avoid spreading the fungus or bacteria.
• Avoid splashing leaves, especially with cold water.
• Increase air circulation by leaving more space between plants.
Symptom: Reddened leaves
Possible problem:
Too chilly temperature
Phosphorus or potassium deficiency
Solutions:
• Move away from cold drafts (windows, drafty doors, fans and air conditioners).
• Use a well-balanced houseplant fertilizer containing phosphorus (P) and potassium (K ).
Symptom: Small leaves (that sometimes wilt shortly after they appear)
Possible problem:
Too much or too little water
Not enough fertilizer
Salt in the water
Not enough light
Solutions:
• Remove the little leaves at the base of the plant.
• Water the plant well, until the water runs out the drainage hole. This will help wash the salts out of the soil. Then let the soil dry out an inch deep (to your first knuckle) between waterings.
• If the soil remains soggy, repot the plant using a sterile potting mix. Clip out any rotting (black or mushy) roots.
• Don’t use softened water (which contains salt) to water your houseplant.
• Move the plant to a sunnier location. Bright, indirect light is often best.
• Fertilize regularly. Once a month during spring and summer (only) is a good regimen for most houseplants. Research your specific plant to see if it might appreciate fertilizer (or a specific fertilizer) more often.
Symptom: Brown leaf tips or leaf edges
Possible problem:
Too cool temperature
Dry soil
Soft water
Too much fertilizer
Low humidity
Salt accumulation
Root rot
Solutions:
• Move the plant to a warmer location (if it’s near a door, drafty window, or air conditioner, for example).
• Water well (until the water runs through the drainage hole; this will help rinse out salt accumulation) on a regular basis, but let the soil dry out an inch deep between waterings (up to your first knuckle).
• Cut back fertilizing schedule to once a month (or less) during the spring and summer. Don’t fertilize in the fall or winter.
• Increase humidity by misting the plant or by placing pots in shallow, pebble-lined trays filled with water.
• Repot the plant if the roots are rotting (they’ll appear dark and mushy). Cut away bad roots before placing in new soil.
Symptom: Burned leaves
Possible problem:
Too much direct sun.
Solutions:
• Trim the sunburnt leaves.
• Move the plant to a place where it gets more indirect — rather than direct — light. Early morning sun and afternoon shade is better than hot afternoon sun.
• Don’t overfertilize, which will make the burn worse.
Symptom: White powder on leaves
Possible problem:
Fungus (powdery mildew)
Poor air circulation
Wet soil
Solutions:
• Remove infected leaves
• Cut back on watering. Allow soil to dry about an inch down (to your first knuckle) before watering.
• Make sure the plant has good drainage.
• If soil remains soggy, repot in a clean pot using a sterile potting mix.
• Provide good air circulation by allowing space between plants.
Symptom: Distorted or curled leaves
Possible problem:
Insects such as thrips, whitefly, or aphids
Overwatering
Root rot
Too much light
Solutions:
• Look for insects and treat for specific attacker, if needed. Isolate the plant so it doesn’t share the bugs with other plants.
• Cut back on watering. Let the soil dry about an inch deep (to your first knuckle) between waterings.
• If the soil remains soggy, repot in a clean pot with good drainage, using a sterile potting mix.
• Move the plant to a less sunny location. Try an east or even a west window if it’s been in a south window. Filter the sunlight (with a sheer curtain, for example) that hits the plant.
Symptom: Webbing on leaves and stems, distorted yellow foliage
Possible problem:
Mites, which are tiny, pale spiders
Solutions:
• Isolate the plant from other plants to avoid spreading the mites.
• Prune the plant to remove infested areas. Discard in the trash outdoors.
• Treat the plant. (One remedy is to spray with a natural insecticidal soap. Test the soap solution on a leaf first, to make sure your plant can tolerate it.)
• To prevent mites, dust the leaves of your plant. A rinse with the sprayer in your kitchen sink occasionally will also help.
• Don’t let your plant soil dry out too much, as water stress can make the plant vulnerable to mites.
Symptom: Sticky leaves
Possible problem:
Scale — caused by oval or round brown insects on the stems and leaves. The insects suck the plant juices.
Solutions:
• Isolate your plant from other plants, to prevent spread of scale.
• Treat the plant. (One remedy is to spray with a natural insecticidal soap containing alcohol. Test the soap solution on a leaf first, to make sure your plant can tolerate it.)
• Remove and replace the top layer of soil, where scale can hide.
• Trim heavily infested leaves and put in the trash outdoors.
Symptom: Failure to flower
Possible problem:
Not enough light
Too much nitrogen in fertilizer (especially if the plant otherwise has excessive growth)
Solutions:
• Move the plant to a sunnier location. Bright, indirect light is often best.
• Cut back on fertilizing. Fertilize no more than once a month in the spring and summer and not at all in the fall and winter. Make sure the fertilizer you use is well balanced for houseplants.
Symptom: Bud drop
Possible problem:
Not enough fertilizer
Too much nitrogen
Underwatering
Overwatering
Spraying with cold water
Solutions:
• Look up the fertilizer requirements for your specific plant, but in general, once-a-month feeding in the spring and summer (only) with a balanced houseplant fertilizer should do the trick.
• Water with room-temperature water, and water the soil rather than the leaves/buds.
• Water well (until the water runs through the drainage hole) on a regular basis, but let the soil dry out an inch deep (up to your first knuckle) between waterings.
Symptom: Crusty white soil
Possible problem:
Salt buildup from watering. You may also see the salt accumulation on the pot.
Solutions:
• Switch to water that isn’t softened. (Softened water can contain high amounts of salt.)
• At each watering, flush the soil so that the water runs out the drainage hole. Be sure to let soil dry out about an inch deep (to your first knuckle) before the next watering, though.
Symptom: Mold on soil, yellow or white
Possible problem:
Fungus, which can be caused by using contaminated potting soil or from poor drainage or overwatering
Solutions:
• Scrape the mold from the soil.
• Let the soil dry out.
• Repot in a clean pot using sterile potting soil.
• Avoid overwatering. Water well, until the water runs out the drainage hole, but allow the soil to dry about an inch deep (up to your first knuckle) between waterings.
Do you have a plant that’s not faring well? Did you find a solution to try here? Do you have solutions to share?
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