When to repot? Repotting can be done at any time, especially if a plant is suffering. But the best time to perform the task is just before growth begins — in most cases, spring; just remember that not all plants have the same growing cycle.
Four signals. It's time to repot if new leaves or stems grow slowly, even with the application of fertilizers; if the soil dries out very quickly; if water doesn't percolate into the soil easily; and if roots start coming out of the drainage hole.
Another test. Pull the plant gently from the pot and inspect the roots. If they are tightly coiled, the plant may be potbound. Some plants, however, prefer this condition; clivia and agapanthus are examples.
Starting Up. Use a pot slightly larger in diameter than the original. Clean it well. If it's a new terra-cotta pot, soak it first.
Taking out. If the plant you're replanting is dry, water it several hours before you remove it from the pot. If you must break a pot to release stubborn plants, hit is as few times as possible to avoid damaging roots.
Once the plant is out, eliminate as much of the old soil as possible. Use a fork or pointed stick to pick away between roots, taking care not to damage them.
Putting in. Put a handful of soil in the bottom of the pot. Position the plant in the new pot at about the same height as in the previous pot; if the leaves are sturdy, you can hold the plant by its foliage. Fill in the empty space between the pot and the root clump, firming the soil with your fingers as you go. Tap the pot several times on the surface of the table and add more soil if necessary. Water the plant and place it in the shade; leave for about 1 week before putting it back in its usual spot. Expect the plant to start growing again in 1 to 2 weeks.
To fertilize or not? Fertilizer isn't needed for the first 6 months if the new potting mix has sufficient nutrients. If not, fertilize about 2 weeks after repotting with an all-purpose houseplant fertilizer.
Stop cats from digging. If you feline companion likes to scratch in the soil of newly potted plants, hide a couple of mothballs in the soil. Some of these pets' favorite plants are ferns, bamboo, catmint, and schefflera (umbrella plant).
Temperamental sorts. Some houseplants, such as the weeping fig (Ficus benjamina) can be traumatized by repotting, suffering leaf drop and arrested growth. If you buy one of these difficult specimens and don't like the pot it's in, simply slip the old pot into a larger, more attractive one.