Question
Why are the leaves on my dieffenbachia are curling inward?


Answer
Hi Anita,

There are many things that can cause the leaves to "curl".  It is hard to say.  The most common causes are irregular watering (over watering can cause leaf roll/curl in many species.), insect damage or infestation, and environmental effects (light, humidity, nutritional deficiencies).  Some leaf deformations are purely developmental, but I am assuming that these deformations are on mature leaves.

Examine your plant thoroughly for insects and discoloration of the soil (white deposits on the soil or at the soil line in the pot).  If you see white mineral deposits on the soil, it is time to repot the plant and wash the accumulated salts from the potting medium.  This can be done by several soakings in clean water allowing the plant to drain thoroughly between soakings.

There is a virus that infects Dieffenbachia which causes the leaves to bend downward, but a mosaic is usually apparent with this virus in addition to the leaf deformations.  

If you find no insects or mineral deposits, then resume a normal watering program, allowing the surface to dry to the depth of approximately 1 inch (2.5 cm) before watering again.  It is also important not to "feed" the plant unless it is actively growing.

Let me hear from you regarding progress.