Root rot is bad news and can make a once thriving houseplant a sad heap of wilted leaves. This disease is frustrating and, at least when caring for houseplants, preventable. Find out how to spot the signs of root rot, when and how you can fix it, and, better yet, how to prevent it.

What Causes Root Rot

Root rot is technically a disease that occurs when the roots are too wet for an extended period. This condition occurs because the plant was overwatered—which everyone does at one time or another—or because the soil did not meet the plant’s needs. Some plants, like cacti, need well-drained soil. If these plants live in dense soil that retains moisture, it can cause root rot. An arid-loving plant in dense potting soil is in danger of root damage.

Fungus in Soil

Root rot can occur when fungus is present in the soil. Prevention is the best course of action, so use high-quality soil when repotting houseplants or source good materials when mixing a homemade batch. It may be tempting to reuse old soil or top off a pot with soil from a garden bed if you don’t have enough, but don’t!

What Happens During Root Rot

An overwatered plant essentially drowns. Water-logged soil prevents the roots from absorbing oxygen, and the plant slowly suffocates. The rot will spread along the roots if untreated, causing further damage. Plants cannot survive without roots, so as the roots rot, the plant declines.

Signs of Root Rot

Plants experiencing root damage will decline. The extent of the dampness determines the extent of the damage and how quickly the plant goes downhill.

Early Signs

In minor cases of slightly too damp soil for a consistent period, the plant will experience stunted growth. All leaves may appear pale, and new leaves will not reach their full size. Slight overwatering will eventually overwhelm the plant, and it will begin to develop full-blown root rot. Fungus gnats are often a precursor of root rot. Take action if you notice these tiny pests flying around because it’s often easier to treat fungus gnats than root rot.

Serious Damage

Yellow leaves are often the first sign of more severe cases of overwatering. Leaf tips typically turn yellow, and the discoloration engulfs the entire leaf before it dies, turns brown, and eventually falls from the plant. The leaves may droop or wilt, too.

Timeline

Root rot can set in after a few days or months. A lot of water at once will quickly kill a plant, but sustained mild overwatering will also destroy it; it will just take longer.

How to Treat Root Rot

Treat minor root rot by holding off on watering until the soil has reached the appropriate level of dryness. For a desert dweller, that means completely dry, but for a tropical beauty, that may mean the top few inches must be dry.

In an extreme case, you may need to trim the roots. Trimming the damaged ends will save the healthy roots. Slide the plant from its pot and gently brush away the soil to examine the roots. Healthy roots are whitish-gray and plump. Unhealthy, rotted roots are black, slimy, and mushy. Trim the dead roots using a clean, sharp knife or pruning shears. Repot the plant using the proper potting medium and a container with drainage. Wait a day or two before watering and get onto a good water routine going forward.

How to Prevent Root Rot

Using an appropriate soil mix and watering as necessary prevent root rot. Most plants can happily live in an all-purpose potting mix, but many cacti and succulents prefer quick-draining soil. Other plants, like orchids and staghorn ferns, do best without soil and thrive in sphagnum moss. The right potting mix will support the plant by shedding water properly to protect the roots.

The other part of the equation is how you water the plant. Feel the soil before watering to gauge the dampness and know your plant. Some plants like to dry out completely, others like to get a drink when just the top inch or two is dry, but the rest of the potting mix is damp. When in doubt, use a moisture meter to better understand and zero in on the perfect time to water.

Always use a pot with drainage holes. Water until excess water drains through the container and remove standing water from the tray or cachepot. Houseplants need water, but too much of a good thing can be fatal, so avoid drowning your plants.