To keep your cacti and succulents healthy, repot them when they need it.
The amount of time between repottings can vary widely. Some species grow more slowly, and may take years before they get potbound.
An obvious exception would be seedlings and young plants you have grown from cuttings. These will need repotting sooner. Allowing their roots to become cramped could harm very young plants.
The best time of year for repotting is when the plant is actively growing. This varies from one species to another. Avoid repotting during a plantís rest period. Typically, late spring to early summer are the preferred times. This gives the plant time to become well established during the growing season.
First, select the new pot. If youíre reusing an older pot you already have, do wash and disinfect it first. Using dish detergent, wash it well. Rinse thoroughly. Then, disinfect in a solution of one part household bleach to ten parts water. Soak the pot for at least ten minutes in this solution. Remove the container from the liquid and rinse thoroughly to remove all residues of the bleach.
Select a pot that is about one size larger. In other words, if the plant is in a three inch pot move up to a four inch pot. Donít jump all the way up to a seven inch. This leaves too much potting soil that can remain damp for too long, which could eventually lead to root rot in a worst case scenario.
Remove the plant from the old pot. If you are dealing with a plant with spines, do this very carefully to avoid getting stuck.
Hold the plant in one hand by the root ball, and check the root system. If the plant was terribly pot-bound, use your fingers to loosen some of the roots encircling the root ball. Otherwise, they will keep growing in the same direction and strangle the plant.
Place a small amount of moist potting soil in the bottom of the new pot. Do not clutter the drainage holes with clay shards or pebbles. This is no longer recommended.
Now, set the plant upright in the center of the new pot. Check to see whether the plant is at the proper level. The top of the root ball should be at least an inch below the rim of the pot. If necessary, make an adjustment by lifting the plant from the pot while you add or remove potting soil in the bottom of the pot.
Finally, fill in around the edges with more moist potting soil. Tamp this gently into place. Barely cover the top of the old potting soil with new soil. Water carefully. This should settle the loose soil into place around the roots.
Generally, I like to keep the plant in partial shade for a day or so after Iíve repotted. This seems to help lessen the shock of transplanting.