Plant care guide
Calathea Root Rot: Signs, Root Check and Rescue by Division
Updated
Why does my Calathea have root rot?
Calathea root rot shows as wilting or yellowing leaves while the mix is still wet, with brown to black, soft roots and a darkened crown. It follows mix that stays wet too long, often in a cool room, and is caused by water-mould and fungal pathogens such as Pythium, Phytophthora and Rhizoctonia.
What to do first
Stop watering and slide the plant out of its pot. Cut away soft, dark roots, keep firm rhizome pieces that still carry a leaf, and repot them in fresh, free-draining mix in a clean pot only slightly larger than the roots.
A calathea that wilts or yellows while its mix is still wet is the one we worry about most. Root rot is the likely cause. It can often be stopped, but only after you look at the roots. More water makes it worse.
Most plants sold as calathea are now Goeppertia. NC State Extension’s Goeppertia genus profile notes that overwatering and cold together can cause rotting stems and drooping leaves.
Signs That Point to Root Rot
University of Maryland Extension’s root rot page lists yellowing, browning and dieback of the leaves, poor growth and wilting. The crown and roots turn brown or black.
UF/IFAS Extension’s Calathea guide gives two causes for wilted calathea leaves: drought stress or root pathogens. The pot tells them apart.
| Check | Points to root rot | Points to a dry plant |
|---|---|---|
| Mix well below the surface | Wet, heavy, may smell sour | Dry, light pot |
| Leaves | Wilting with yellowing, old and new leaves together | Limp, crisp at the edges |
| Roots | Brown to black, soft or mushy | Firm and pale |
| After watering | No change, or worse | Leaves firm up |
The RHS houseplant problems page links old and new leaves yellowing together, with dark, mushy roots, to overwatering. Virginia Cooperative Extension’s watering guide adds foul-smelling mix and fungus gnats.
If the mix is dry and the roots are firm, this is not your problem. See the calathea drooping guide instead.
What the Roots Tell You
Maryland describes three common rots:
- Pythium. Roots are brown to black and soft. The outer layer pulls away from the core and leaves a fine, hair-like thread. Much of the root system may stay behind in the pot.
- Phytophthora. Root tips turn dark brown and quickly go soft. The lower stems can blacken, and plants wilt even in moist mix.
- Rhizoctonia. Coarse, reddish-brown threads like spider webs grow over roots and stem bases in warm, moist conditions.
Clemson Extension’s houseplant disorders factsheet adds that stems may be girdled at soil level by a ring of brown or black tissue.
Calatheas grow from rhizomes. UF/IFAS describes them as rhizomatous or tuberous herbs. Squeeze the rhizome too. Firm tissue can be saved; soft, collapsing tissue cannot.
How to Rescue a Calathea With Root Rot
- Stop watering. Empty the saucer or outer pot. The RHS suggests checking for water collected in the base and tipping it away.
- Remove the plant and loosen the old mix. Work over newspaper so you can see every root.
- Cut away all soft, dark roots with clean scissors. Clean the blades between cuts.
- Divide if the clump is mixed. UF/IFAS describes propagating calathea by dividing the rhizome so each piece has at least one leaf. Keep only firm pieces with healthy roots and a leaf.
- Repot in fresh mix and a clean pot. Maryland advises clean or new pots and sterile potting media, never garden soil. The RHS recommends free-draining, moisture-retentive, peat-free compost with around ten per cent grit, in a pot one or two sizes larger than the rootball.
- Keep it apart from your other plants. Maryland advises separating infected plants from healthy ones and throwing away severely infected plants.
Do not feed a plant with damaged roots. Wait for new leaves first.
Aftercare and Watering
Water again only when the surface of the mix has dried slightly, as UF/IFAS advises. Keep the mix moist but not wet. NC State’s Goeppertia makoyana profile asks for moist, well-drained mix with organic matter and perlite.
Check by touch, not by calendar. Virginia Cooperative Extension suggests pushing a finger 2.5–7.5 cm (1–3 in) into the mix, depending on pot size. It warns that overwatering is about how often you water, not how much. Do not leave the pot standing in drained water for more than 60 minutes.
Keep the room warm. UF/IFAS gives 18–27 °C (65–80 °F) for calatheas indoors and warns of chilling injury below 13 °C (55 °F). Cold, wet mix is where rot starts.
Preventing It Next Time
- Water less in winter. The RHS says to take care not to overwater in winter, when growth slows.
- Use a pot with a drainage hole and avoid overpotting.
- Inspect new plants before placing them with your others, as Maryland advises.
- Keep humidity up with air, not with wetter mix. Our calathea curling leaves guide covers humidity.
Judge recovery by the next leaves. Leaves that yellowed will not turn green again. If the plant collapses further, use a healthy division to start again. Our houseplant root rot guide covers the general method, and the calathea hub links our other guides.
References
- University of Maryland Extension: Root rots of indoor plants
- Clemson Cooperative Extension, HGIC 2251: Houseplant Diseases & Disorders
- UF/IFAS Extension: Cultural Guidelines for Commercial Production of Interiorscape Calathea (EP285)
- NC State Extension Gardener Plant Toolbox: Goeppertia
- NC State Extension Gardener Plant Toolbox: Goeppertia makoyana
- RHS: How to grow calatheas
- RHS: How to help a poorly houseplant
- Virginia Cooperative Extension: Properly Watering Container Houseplants (SPES-804)
How this guide was put together: University of Maryland Extension, Clemson Cooperative Extension, UF/IFAS Extension, NC State Extension, Virginia Cooperative Extension and RHS guidance.