Root Rot in Houseplants: Signs, Rescue and Prevention

Quick Diagnosis

What you see	What it means	What to do
Wilting while the soil is still wet	Rotting roots can't take up water¹⁵	Don't water. Check the roots.
Wilting, and the pot feels light	The plant is probably just dry⁵	Water well. Very dry mix may need a soak⁵.
Older, lower leaves yellow and drop; the plant looks stunted	Possibly root rot, which can look like a nutrient shortage¹³. Low light, cold and overwatering cause this too⁴.	Check the mix and roots. See yellow leaves.
Brown or black, soft roots that may smell bad	Root rot¹²⁵	Trim the rot and repot, or start over.
Root skin slides off when pulled, leaving a thin thread	That root has rotted³	Cut it back to firm, white tissue.
Brown or black ring around the stem at soil level	Rot has reached the stem²	Root cuttings from healthy shoots⁵.
Firm, white roots, but the mix stays soggy	Too much water or poor drainage, but no rot yet²⁴	Let the mix dry more between waterings. Check that the pot drains.
Brown leaf tips or edges, healthy roots	Probably not root rot; salt buildup is one cause⁵	See brown leaf tips.

What Causes Root Rot

Roots need air as well as water. In waterlogged potting mix, water fills the air spaces and roots can drown⁶. Overwatering also favors root diseases².

The main culprits are the water molds Pythium and Phytophthora and the fungi Rhizoctonia and Fusarium¹⁴. Water molds spread by swimming spores and are not true fungi⁴. Most of these organisms thrive in wet mix, and some survive a long time in soil or plant debris¹. They can come from garden soil, reused mix, drainage water or infected new plants¹⁴. Fungus gnats can spread them too⁴.

Common reasons a mix stays too wet:

Watering too often².
No drainage holes, or a pot left standing in water²⁵.
A pot much larger than the root system⁵⁷.
Old, compacted mix, or roots so crowded they block drainage⁴⁷.
Cold: wet mix plus cold temperatures often leads to root rot⁵.

Salt buildup from fertilizer is sometimes linked to root rot as well⁴⁵. You can't tell by eye whether roots died from waterlogging or infection; it often takes a lab test³⁶. By the time leaves show symptoms, root decay is often well advanced⁶.

How to Check the Roots

Check the roots whenever a plant wilts, before you water again⁴⁵.

Unpot it. Hold the main stems and lift while holding the pot down. If it sticks, lay the pot on its side or tip it upside down, cradling the root ball⁷.
Feel and smell. Wet, foul-smelling mix at the bottom of the pot points to overwatering and rot⁵.
Rinse. Wash some mix off so you can see the roots³.
Compare. Healthy roots are white, at least under the outer skin, and firm rather than limp³⁴. Rotted roots are brownish to black and soft, often starting at the tips²³⁴.
Pull gently. If the outer layer slides off and leaves a thin, stringy core, the root has rotted³.
Check the stem base. A brown or black ring at soil level means rot has reached the stem².

Some plants have naturally brown roots, so judge texture and the pull test, not just color³. Only a lab can identify the organism³⁶, so for a valuable plant or several sick plants, ask a plant clinic.

How to Save a Plant With Root Rot

A rescue works best when only part of the root system has rotted².

Unpot the plant as described above, without watering it first.
Remove the old mix. Shake and rinse it off the roots³. Throw it away, along with any drainage water, since both can carry root rot organisms¹.
Trim the rot. With clean scissors or pruners, cut off every soft, brown or black root, back to firm, white tissue²⁴⁷.
Judge what is left. If only a few roots were rotted, carry on. If most were dark, soft and dead, go to When to Start Over².
Disinfect tools and work surfaces with a 10% bleach or detergent solution, or alcohol¹.
Choose a clean pot with drainage holes. Use a new pot, or a clay pot scrubbed and rinsed in 1 part household bleach to 9 parts water¹². University of Wisconsin–Madison specialists advise throwing out plastic pots that held a plant with root rot¹. Pick a size that fits the remaining roots, since too large a pot invites rot⁵.
Repot in fresh mix. Use bagged potting mix, never garden soil, and skip any gravel layer¹. Set the root ball's top just below the rim, then fill and firm gently⁷.
Water once, then wait. Water until a little drains from the holes⁷, then empty the saucer². After that, give enough water to prevent drought stress, but don't overwater¹.
Give it time. Keep the plant warm and away from cold windows⁵. Skip fertilizer until it grows again, since excess fertilizer can also harm roots³. Dead roots don't recover; the plant must grow new ones³.

When to Start Over

UW–Madison specialists say throwing out a plant with root rot is often the best and most cost-effective choice¹. Start over when most roots are dark, soft and dead², or when rot rings the stem at soil level².

If some shoots are still firm and free of rot, take stem cuttings from them and root them⁵. Use only stems with no dark or soft spots. Then discard the old plant, its mix and, if it is plastic, its pot¹. Clean any tools and surfaces it touched¹.

How to Prevent Root Rot

Check before you water. Lift small pots: a light pot needs water⁵. A plant that wilts in wet mix needs a root check, not more water¹⁵.
Use pots with drainage holes. Repot plants growing in pots without them⁵.
Never leave pots standing in water. Empty saucers and decorative outer pots after watering¹².
Skip the gravel layer. Rocks or gravel in the bottom of a pot do not improve drainage. UW–Madison says they can actually inhibit it¹.
Size up gradually. A new pot should be no more than a third larger than the old one. For pots under 25 cm (10 in) across, go about 2.5 to 5 cm (1 to 2 in) wider and deeper⁷.
Refresh old mix. Mix compacts as it ages, so repot every few years⁴⁷.
Use fresh potting mix, never garden soil, which often contains root rot organisms¹.
Keep plants away from cold drafts, especially when the mix is wet⁵.
Go easy on fertilizer, and now and then run plenty of water through the pot to wash out salts³⁴⁵.
Inspect new plants. Before you buy, slide the plant out of its pot and pass on any with discolored roots or stems¹⁴.

Watering needs vary by plant, so check the guide for yours: monstera, pothos, snake plant, fiddle leaf fig or peace lily.

How Plantalk AI Helps

In Plantalk AI's plant health tools, you can send the Plantie Assistant a photo of a symptom, such as yellow leaves, for step-by-step answers. A Plantiemoji sensor, sold separately, shows live soil moisture readings in the plant's Environment view, so you can check the mix before watering. The Care screen lists what to water and check each day. The app's answers are guidance; for a serious disease problem, also ask a local nursery or plant clinic.

Health over time chart for a plant in Plantalk AI — Each plant's health score and how it changes over time.Get the app

Common Questions

What Does Root Rot Look Like?

Rotted roots are brown to black, soft or limp, and may smell bad¹²³. Their outer layer often slides off when pulled, leaving a thin thread³. Above ground, look for wilting in wet mix, yellowing leaves and slow growth¹.

Can a Plant Recover From Root Rot?

Yes, if only a few roots are affected and you trim them and repot in fresh mix². Dead roots don't recover, so the plant must grow new ones³. If most roots are dark, soft and dead, Clemson Extension advises discarding the plant, though healthy shoots may still root as cuttings²⁵.

Is It Overwatering or Root Rot?

Often both: overwatering cuts the oxygen roots need and favors root diseases². Roots killed by waterlogging can look just like roots killed by Phytophthora, and telling them apart often takes a lab test⁶. Either way, the rescue starts the same: check the roots, remove the dead ones and water less.

Do Hydrogen Peroxide or Fungicides Help?

UW–Madison does not recommend fungicides for houseplant root rot, because few products are sold to home gardeners and those are expensive¹. In the UK, the Royal Horticultural Society says no chemical treatments are available to gardeners for Phytophthora root rot⁶. Fungicides work only against certain groups of organisms and cannot revive dead roots³. None of the sources behind this guide recommend hydrogen peroxide.

Sources

Root Rots on Houseplants, University of Wisconsin–Madison Division of Extension (Wisconsin Horticulture)
Houseplant Diseases & Disorders, Clemson Cooperative Extension, Home & Garden Information Center
Fungal Root Rots and Chemical Fungicide Use, Penn State Extension
Houseplant Problems, UC Statewide Integrated Pest Management Program, University of California Agriculture and Natural Resources
Problems Common to Many Indoor Plants, Missouri Botanical Garden
Phytophthora root rot, Royal Horticultural Society
How to repot a plant, Royal Horticultural Society

About this guide. Drafted by the Plantalk AI team with AI assistance, checked against the sources listed on each page, and reviewed by an expert before publishing. Reviewed by Bingqing Qi, Wageningen University & Research, on November 9, 2026. Spotted something that needs fixing? Tell us.