Plant problems A–Z
Common houseplant and garden diseases, symptoms, and pests — how to recognize each one and what to do about it.
Symptoms
Brown leaf tips
Low humidity, fluoride or salt buildup, underwatering, fertilizer burn, or heat stress. The pattern of browning narrows it down.
Brown spots on leaves
Fungal leaf spot, sunburn, fertilizer burn, cold damage, or pests; shape, halo and position identify the cause.
Curling leaves
Leaves curl inward from underwatering, heat or pests; downward from overwatering, cold or root problems.
Drooping or wilting
Wilting with dry soil is thirst; wilting with wet soil is root rot; sudden droop after moving is shock.
Leaves falling off
Leaf drop from shock, light change, over- or underwatering, drafts, or pests; green vs yellow leaves narrow it down.
Overwatering vs underwatering
Both cause yellow, drooping leaves; soil moisture, leaf texture (soft vs crispy) and which leaves go first separate them.
Sticky leaves
Honeydew from sap-sucking pests (scale, aphids, mealybugs, whitefly) or natural guttation; check undersides first.
White spots on leaves
Powdery mildew, mealybugs, mineral deposits from hard water, or edema — texture and location tell them apart.
Yellow leaves
Seven causes: overwatering, underwatering, light, nutrients, root rot, sunburn, natural aging. Which leaves yellow first tells you which one.
Pests
Aphids
Soft-bodied green, black or white insects clustered on new growth; cause curled, sticky leaves.
Fungus gnats
Small black flies hovering over soil; larvae feed on roots in constantly moist potting mix.
Mealybugs
White, cottony insects in leaf axils and on stems that suck sap and leave sticky honeydew.
Scale insects
Brown or tan immobile bumps on stems and leaf undersides; armored or soft scale that drips honeydew.
Spider mites
Tiny mites (Tetranychus urticae) that stipple leaves and spin fine webbing; thrive in dry, warm air.
Thrips
Slender 1–2 mm insects that rasp leaf surfaces, leaving silvery streaks and black specks of frass.
Diseases
Leaf spot
Fungal or bacterial spots with dark margins or yellow halos; spread by splashing water and wet leaves.
Powdery mildew
White powdery coating on leaf surfaces caused by Erysiphales fungi; wipes off with a finger and spreads via airborne spores.
Root rot
Brown or black mushy roots from waterlogged soil (Pythium, Phytophthora, Fusarium); yellowing, wilting despite wet soil.
Plant guides
Fiddle leaf fig brown spots
Dark spots spreading from the leaf center mean root rot; crispy edge spots mean underwatering or dry air; sunburn bleaches.
Monstera yellow leaves
Usually overwatering or low light; also natural drop of the oldest leaf, nutrient shortage, or pests.
Peace lily drooping
Dramatic wilting from thirst recovers in hours after watering; drooping with wet soil signals root rot.
Pothos yellow leaves
Overwatering first, then low light, root-bound pots, and cold drafts; pothos forgive underwatering more than wet feet.
Snake plant mushy leaves
Soft, wrinkled or collapsing leaves are rot from overwatering or cold; cut back to firm tissue and repot dry.