As a general rule, you can repot once a year in late winter to early spring. This is typically before your plants go through their yearly growth spurts. However, this repotting schedule should not be the taken as a strict rule. Every species is different, and even every individual plant within the same species will have varying needs. It depends greatly on their environment.
Plants are great at telling us when they need something. If something is wrong, their leaves will turn brown or yellow, they’ll start wilting, getting lanky, or just stop growing. When a plant needs to be repotted, there are a few signs to look for.
When your plants get straggly, pale, or refuse to grow larger they could need fresh nutrients or a larger pot. Roots sticking out of the drainage holes is a definite sign your plant needs a new home. When the soil is dry, gently remove your plant from the pot. See if thick roots have coiled around the edges. If they have, this means your plant has become pot bound and the roots need more space to grow.
It’s important to be familiar with the species of plant you’re growing. Some plants, such as African violets, aloe, and spider plants, prefer to be root bound. Peace lilies and Christmas cactus thrive on being pot bound and won’t actually produce flowers otherwise.