Root-bound plants
When roots have filled a pot and circle the inside, so the plant dries out fast, grows slowly and cannot take up water and nutrients.
Also known as: Pot-bound, Rootbound
Symptoms and identification
Roots push out of the drainage holes or grow in a tight mat around the surface. Water runs straight through and the pot dries within a day or two. The plant is stunted, leaves are small or yellow, and growth stalls even with feeding.
Causes
The plant has simply outgrown its pot or has been in the same potting mix for years. Plants that grow quickly become root-bound sooner, and so do those kept in a pot too small for their size.
Organic treatment
Slide the plant out, loosen or tease apart circling roots, trim off a quarter of the very dense ones if needed, and repot into fresh mix in the next size up. Water well and keep out of strong sun for a week. Spring is the best time.
Prevention
Check the roots every year or two, repot into a pot only 2 to 5 cm wider, and refresh the mix. Pick a pot with drainage holes.
Chemical treatment (use with care)
No chemical treatment is needed. Repotting is the cure.