Problems and Symptoms

When a plant looks unhappy, the cause is usually in how it is grown. As UC IPM's Houseplant Problems Pest Notes put it, most houseplant problems come from improper care and conditions that are unfavorable for growth, and symptoms are often caused by several factors at once. Diagnose first, then change one thing at a time.

Symptom finder

Watering problems

Iowa State University Extension lists the classic signs of overwatering: yellowing or browning leaves, leaf drop, wilting from a damaged root system, crown rot, fungus gnats and eventually death. The trap is that a waterlogged plant wilts, which prompts more water. Always check the soil before watering, use a pot that is not oversized and has a drainage hole, and never leave the plant standing in a saucer of water.

Underwatered plants wilt too, but the soil is dry and pulls away from the pot edge, and leaves turn crisp rather than soft. Soak the root ball thoroughly, ideally by setting the pot in a basin of water for 20 to 30 minutes.

Detailed guides: yellow leaves, overwatering, root rot and drooping.

Brown tips and leaf edges

According to Iowa State's guide to environmental problems, low humidity is the most common reason for brown leaf tips, especially in winter. Letting the soil dry out too long between waterings, fertilizer salt buildup and fluoride or chlorine in tap water are the other usual suspects; spider plants, dracaenas, prayer plants and calatheas are especially sensitive. Trimming the brown part improves the look, but new tips will brown unless the cause is fixed. More in brown tips.

Light problems

Leggy growth with long gaps between leaves is almost always low light. Move the plant closer to a bright window or add a grow light, then prune the stretched stems so new growth comes in compact. Too much light shows as bleached or brown patches on the side facing the window, usually right after a move. See leggy plants.

Leaf drop and no blooms

Plants such as weeping fig drop leaves after almost any change: a move, a draft, a cold window in January. Keep conditions steady and the plant usually regrows within weeks. Failure to bloom is usually a light problem; some species also need a day-length or temperature cue, which is covered in not blooming and on each plant's card.

Mold, spots and rot

White fuzz on the soil surface is a sign the soil stays wet too long; it rarely harms the plant directly. Leaf spots on indoor plants are more often caused by overwatering, cold water or chemical sprays than by infection, since fungal and bacterial leaf diseases are uncommon indoors unless a plant recently came from a greenhouse or the outdoors. See mold on soil and leaf spots.

When to start over

UC IPM is candid that some plants cannot be brought back: if the roots are mostly gone or a pest is entrenched, it can be better to take healthy cuttings or replace the plant. Many common houseplants, including pothos, tradescantia and snake plant, root easily from cuttings, so a failing plant is often a chance to propagate rather than a loss. Each plant in the catalog has its own symptom table.