A houseplant in trouble rarely has one obvious cause. Yellow leaves can mean overwatering, underwatering, too little light, or simply an old leaf dying naturally. Brown tips can mean dry air, salt build-up, or over-fertilising. Wilting can mean the plant is thirsty, or that its roots have rotted and cannot take up water at all. Troubleshooting houseplants is therefore a process of elimination: look at the symptoms, check the basic conditions — light, water, temperature, pot and soil — and fix the most likely cause before trying anything else. This guide walks through that process.
Start with the basics: light, water and soil
Before you diagnose a disease or reach for a treatment, check the basics. Is the plant getting the light its species needs? Our data lists monstera deliciosa and most tropical plants at bright indirect light, while snake plant laurentii tolerates low light — a mismatch here explains more problems than any pest. Is the soil wet or dry? Push a finger two inches into the mix: if it is soggy, the plant is overwatered; if it is bone dry all the way down, it is underwatered. Is the pot draining? Water should run from the drainage hole within seconds of watering, and the saucer should be emptied afterwards.
Check the plant's position: is it in a cold draught, above a radiator, or in the path of an air-conditioning vent? Our houseplants temperature guide explains how temperature and draughts cause damage that looks like disease. Check the leaves: are the symptoms on old leaves only, which may be natural ageing, or on new growth, which points to a current problem? And check the roots if you can: tip the plant out and look for firm, pale roots, which are healthy, or dark, mushy roots, which are rotted. If you are unsure what you are seeing, check your local extension service for help with diagnosis.
Yellow leaves: the most common symptom
Yellow leaves are the most common houseplant complaint, and the cause depends on the pattern. Yellow lower leaves on an otherwise healthy plant are often natural: old leaves die as new ones grow, and one or two yellowing leaves a month is normal. Yellow leaves throughout the plant, with wet soil, usually mean overwatering — the most common cause of all. Yellow leaves with dry soil and crispy edges mean underwatering. Yellow leaves with pale new growth and good watering usually mean too little light, and yellow leaves with brown tips after feeding usually mean over-fertilising or salt build-up.
Fix the cause, not the symptom: let wet soil dry out and water less often; water dry soil thoroughly; move a light-starved plant closer to a window; flush a salt-affected plant with plain water and stop feeding for two months — see our fertilizing houseplants guide. Remove yellow leaves once they are fully yellow, because they will not recover, but do not remove leaves that are only partly yellow, because they are still feeding the plant. If yellow leaves keep appearing after you have fixed light and water, check the roots for rot and consider repotting into fresh mix — see our houseplants transplanting guide.
Brown tips, brown edges and leaf drop
Brown leaf tips are usually a humidity or salt problem. Tropical plants such as calathea orbifolia and boston fern show brown tips when the air is too dry, especially in heated homes in winter. The fix is to raise humidity by grouping plants, using a pebble tray or a humidifier — misting helps only briefly. Brown tips can also mean salt build-up from fertiliser or tap water; flush the pot with plain water and use rainwater or filtered water if your tap water is hard.
Brown edges and sudden leaf drop often mean cold damage or a draught, especially in fiddle-leaf fig, which drops leaves dramatically when moved or chilled. Leaf drop after a move is often shock rather than disease: give the plant two to three weeks of steady care in one spot before changing anything else. Crispy brown patches in the middle of leaves usually mean sun scorch — move the plant out of direct sun. Our houseplants sunlight requirements guide explains how to judge the light.
Wilting, drooping and root rot
A wilting plant with dry soil simply needs water: water thoroughly until it runs from the drainage hole, let it drain, and the plant should recover within hours. A wilting plant with wet soil is more serious: its roots have rotted and cannot take up water, so watering more makes it worse. Tip the plant out, trim away dark, mushy roots with clean scissors, repot into fresh, free-draining mix in a pot with drainage holes, and water sparingly until new growth appears. See our houseplants soil preparation guide for a mix that drains well.
Drooping without wilting can mean the plant is cold, or that it is a prayer plant or calathea folding its leaves at night, which is normal. A plant that droops every afternoon and recovers at night is usually thirsty or in too much sun. A plant that droops permanently and does not respond to water needs its roots checked. Do not feed a wilting or drooping plant until it recovers — fertiliser on stressed roots makes the problem worse.
Pests: what to look for and what to do
The common indoor pests are spider mites, mealybugs, scale, aphids, fungus gnats and thrips. Spider mites make fine webbing and tiny yellow speckles on leaves, and love hot, dry air. Mealybugs look like small white cotton-wool lumps in leaf joints. Scale looks like small brown bumps on stems and leaves. Aphids cluster on soft new growth. Fungus gnats are small flies that rise from the soil when you water, and their larvae live in wet mix. Thrips cause silvery streaks and distorted leaves.
Isolate an infested plant immediately, so pests do not spread to the collection. For a light infestation, wipe leaves with a damp cloth, remove visible pests by hand, and wash the plant with a gentle spray of water. For a heavier infestation, use insecticidal soap or neem oil according to the label, repeating the treatment every week for three or four weeks, because eggs hatch after the first treatment. Let the top of the mix dry between waterings to control fungus gnats. If you cannot identify a pest, check your local extension service for identification help before treating.
Frequently asked questions
Why are my houseplant leaves turning yellow?
Usually overwatering, underwatering, too little light, or natural ageing of old leaves. Check the soil moisture and the light first, then look at the pattern — yellow lower leaves alone are often normal.
Why does my houseplant keep wilting?
If the soil is dry, it needs water. If the soil is wet and it still wilts, the roots have rotted and cannot take up water — check the roots, trim rot, and repot into fresh mix.
What are the white fluffy things on my houseplant?
Probably mealybugs. Isolate the plant, remove them by hand or with a cotton bud dipped in rubbing alcohol, and treat with insecticidal soap, repeating weekly.
Why are the tips of my plant's leaves brown?
Usually dry air, salt build-up from fertiliser or tap water, or inconsistent watering. Raise humidity, flush the pot with plain water, and water evenly.
When should I ask for help with a houseplant problem?
When the plant keeps declining after you have fixed light, water and temperature, or when you cannot identify a pest or disease. Check your local extension service — a photo and a description of the symptoms will help them diagnose it.