Overwatering

In short

Overwatering is not about the amount of water poured in once, but about potting mix that stays wet for too long. Wet mix holds too little air, fine roots die from lack of oxygen, and the plant then wilts because damaged roots cannot take up water. It is one of the most common causes of houseplant decline and opens the door to root rot and fungus gnats.

How it looks

Wilting or yellowing of the lower and inner leaves while the potting mix is still moist; both old and new leaves may yellow at the same time. Leaves can be limp and soft rather than crisp. The pot feels heavy, water may pool in the saucer or pot base,. When unpotted, healthy roots are white (at least under their outer covering), whereas overwatered roots are dark and mushy.

Signs

Wilting despite wet soil; yellowing lower leaves; leaf drop; soft, rotting stem bases; mushy roots; fungus gnats around the pot; in advanced cases leaf scorch and plant death.

What favours it

Watering on a fixed schedule rather than by need; poorly drained or dense potting mix; pots without drainage holes; saucers or cache pots left holding water; low light and cool temperatures that slow water use, especially in winter.

Prevention

• Water only when the plant needs it: check the mix a few centimetres down, lift the pot to judge its weight, or push a dowel into large pots (moist mix sticks to it).
• Use a well-drained potting mix suited to the plant and pots with drainage holes.
• Empty saucers and decorative outer pots after watering.
• Water less in cooler, darker periods when growth slows.

Treatment

Start with the first step and move down only if the problem persists.

1. Stop watering and let the mix dry to the level the plant prefers; move the plant to brighter light to speed drying if it tolerates it.
2. If the plant keeps wilting in wet mix, unpot it and check the roots; trim away mushy, dark roots with clean tools.
3. Repot into fresh, well-drained mix in a pot sized to the remaining roots.
4. Treat for root rot if roots are badly affected, and watch for fungus gnats.

Pros and cons

Look-alikes

Underwatering

Underwatered plants wilt with bone-dry, light pots and crisp leaf edges; overwatered plants wilt with wet, heavy pots and soft yellow leaves.

Root rot

Root rot is the disease that commonly follows overwatering; check roots for dark, mushy tissue.

Nutrient deficiency

Nitrogen deficiency yellows older leaves evenly while the mix is not constantly wet and the roots are healthy.

Edema

Edema is a related wet-soil disorder that shows as corky blisters on leaf undersides.

Affected plants

All potted plants; succulents, cacti, orchids and plants in large or undrained pots are especially vulnerable.

Related

• Root rot
• Underwatering
• Edema
• Fungus gnats
• Choosing the right pot size
• Drainage in containers
• Watering technique

Sources

1. Overwatered Indoor Plants — University of Maryland Extension
2. How to help a poorly houseplant — RHS
3. Houseplant Problems — UC Statewide IPM Program
4. Houseplant Diseases & Disorders — Clemson HGIC

Written in our own words from these sources. Check a product label before using any treatment.