Can I save a plant with root rot?

Yes, if you catch it early. Remove the plant, cut off the dead roots, and repot it in clean, dry soil.

How often should I check the roots?

You do not need to check them unless you see signs of distress. Over-handling the roots can cause unnecessary stress.

Giant knotweed: root rot, causes and fixes

Check these first

Smell the soil for a sour or rotten odor.
Check if the pot has adequate drainage holes.
Feel if the soil is constantly soggy.

Likely causes

Overwatering
Possible
How to tell: The leaves turn yellow and wilt even when the soil is wet. If you pull the plant out, the roots will look mushy, dark, and smell unpleasant.
What to do: Stop watering immediately and allow the soil to dry out. If the rot is advanced, trim away the black, mushy roots and repot in fresh, well-draining soil.
Poor Drainage
Possible
How to tell: Water pools at the bottom of the pot or the soil stays soggy for more than 2 weeks. This prevents oxygen from reaching the roots.
What to do: Ensure your pot has large drainage holes at the bottom. Use a potting mix amended with perlite to improve aeration and drainage.

Root rot in other plants

Find out what's wrong with your giant knotweed

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

If the stems become soft or mushy at the base, the rot has likely moved into the crown. This is a serious condition that may be difficult to reverse.

Stopping it coming back

Always let the top inch of soil dry out before watering again, and never let the pot sit in a saucer of standing water.

Giant knotweed: root rot? Check yours with a photo

Every plant is a little different. Take a photo of your giant knotweed and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

Get the app · Or check it from a photo now, free

Questions people ask

Can I save a plant with root rot?: Yes, if you catch it early. Remove the plant, cut off the dead roots, and repot it in clean, dry soil.
How often should I check the roots?: You do not need to check them unless you see signs of distress. Over-handling the roots can cause unnecessary stress.

Is my giant knotweed suffering from root rot?