How to Grow Cactus Indoors

Choose a planting container that complements your grouping of cacti. Terracotta is a wonderful choice as it lends itself well to the natural scene you are trying to create. The largest cactus should be four times the height of the container. The container should have room for a layer of cactus soil on the bottom that allows your smallest cactus to reach above the container's rim.

Spread the specially formulated cactus-growing medium 2 inches deep in the container. Don't use regular potting soil -- it's too moist and rich for cactus plants.

Remove the cactus plants from their containers, using care not to prick yourself on the spines. Position your taller plants in the back, the medium-size plants in the middle and the smaller plants in the front. Rearrange them until you get the right look.

Plant each cactus, beginning with the back and working your way to the front. Add soil between the plants with a spoon.

Layer gravel or sand over the potting mixture, using a spoon to get it into small crevices between plants. Add decorative rocks to simulate boulders or small pebbles to introduce color.

Sit the cactus garden on a sunny windowsill.

Water the cactus plants sparingly -- they need very little water and do not like moist soil. A few teaspoons may be all that is needed. Overwatering is the most common error made when growing cactus. Water just once a month during the winter. Monitor your cactus plants for their health and growth; adjust watering to maintain healthy growth.