Inconsistent watering

What's happening

Croton likes its soil kept lightly and evenly moist. When watering bounces between forgetting it until the soil is bone dry and then drenching it, the roots can't keep a steady supply to the leaves. The plant reacts by dropping leaves — especially lower ones — and the bottom leaves may wilt or go limp before they fall.

How to fix it

Get on a consistent schedule. Water when the top inch of soil feels dry, soaking thoroughly until it drains from the bottom, then let the top inch dry again before the next watering. Don't let it dry out completely, and don't leave it sitting in a saucer of water. Checking the soil with your finger every few days, rather than watering on a fixed calendar day, keeps the moisture even and steady, which is what stops the drop.

This is general guidance based on common symptoms; individual plants vary.