Signs of Overwatering

The order they usually appear

Sign by sign, and what each one means

Fungus gnats. The earliest and most under-read signal. They breed in persistently damp mix, so a population of them is direct evidence that the top of the pot never dries. Catching it here means you have lost nothing yet.

Yellowing lower leaves. Older leaves go first because the plant sacrifices them under stress. Yellowing appears on the overwatering list and not the underwatering one, which makes it usefully diagnostic - though it is also caused by other things, so check the soil before concluding.

Wilting with wet soil. The most misread symptom in houseplant care. Damaged roots cannot take up water, so a plant with a saturated root ball wilts exactly like a thirsty one. NC State Extension is explicit that people misinterpret wilting lower leaves as insufficient water and add more. The diagnostic checks are here.

A heavy pot. The counterpart of the lightweight container on the underwatering list. Lift it. A saturated root ball is dramatically heavier, and this is fast, free and reliable.

Mushy leaves and stems. Soft, sometimes translucent tissue, particularly at the base of leaves and where stems meet the soil. This is structural damage rather than stress and it does not reverse - the affected tissue is gone.

Rotten-smelling soil. Anaerobic conditions and decomposing roots. Healthy mix smells earthy. A sour or sulfurous smell means the process is well under way, and it is time for the full root-rot procedure.

Stunted growth. Appears under both stresses, so it is a signal that something is wrong rather than which thing.

Things that look like overwatering but are not

Brown crispy leaf tips. That is on the underwatering list, along with dry brittle leaves and curling. It can also be low humidity or salt build-up. It is not overwatering.

White crust on the soil surface. Accumulated mineral and fertilizer salts, especially where a pot has been bottom watered without periodic flushing. It indicates a watering-method problem, not a volume problem.

Sudden leaf drop after moving the plant. Usually acclimation to a light change rather than water. Check the soil before treating it as anything else.

Old lower leaves yellowing slowly on a healthy plant. Normal. A plant sheds its oldest leaves as it grows. The signal is the rate and how many.

Catching it earlier next time

Overwatering is a frequency problem, not a volume problem: the root zone stays wet too often and never gets air. The RHS corrective is to water less often but more thoroughly and let the surface dry between times, and the way to make that operational is to check before every watering rather than counting days.

For pots deep enough that a finger will not reach the root zone, a probe is the practical answer, and it is the honest purchase for someone whose failure mode is overwatering - a reservoir planter is not.