All cactus plants are members of the Cactaceae family, and there are thousands of species of cactus. There are two large groups of cacti grown as houseplants; both are popular and familiar, and both can thrive indoors with relatively little maintenance.
The desert cacti are the more "traditional" cacti, usually covered with spines or hair and often growing in paddles, balls, or obelisks. Forest cacti grow in wooded areas, ranging from temperate forests to subtropical and tropical regions. The most well-known forest cacti may be the Christmas cactus. Both desert and forest cacti boast beautiful blooms, but they have very different growing habits.
|Common Name||Cactus, desert cactus, forest cactus|
|Plant Type||Succulents (with some exceptions)|
|Mature Size||Varies depending on variety|
|Sun Exposure||Some direct sun; quantity varies depending on variety|
|Soil Type||Well-draining sandy soil|
|Soil pH||5.5 to 7|
|Hardiness Zones||9 through 11|
|Native Area||Deserts and rainforests around the world|
How to Grow Cactus Indoors
Desert cacti have a unique, stark beauty, and some of the desert cacti feature the most beautiful flowers in the plant kingdom. Growing desert cacti is not difficult. These are among the toughest of all houseplants. Successful gardening does require sticking to some pretty simple rules. There are dozens of kinds of desert cacti on the market today. For the most part, the rules governing their growth are the same. Some species of cacti will bloom after three or four years in cultivation. Others will take longer or never bloom indoors.
The forest cacti grow in tropical and subtropical regions throughout the world. They are often climbing or epiphytic plants that cling to trees. The most famous among these is the Christmas cactus, which is native to Brazil. Today, Christmas cacti are available with blooms in red, pink, purple, and even yellow. They make excellent hanging plants.
Coaxing multiple blooms from a Christmas cactus (or the closely related Easter cactus) takes a little planning. Before you want the plant to flower, cut it back and induce a rest period when watering and fertilizer is reduced, and the plant is kept cool (about 50 F to 55 F). After one to two months, move the plant to a warmer place and resume watering. Buds will soon begin to show. It is also essential to move the plant outside during the summer.
- Strong light is essential for healthy desert cacti, especially in the winter. Some species may scorch in direct summer sun if they haven't been hardened off first.
- Forest cacti like bright, but not direct, sunlight. Move them outside during the summer.
- Pot desert cactus into a fast-draining cacti mix. If one is not available, amend the regular potting soil with inorganic agents like perlite to increase drainage and aeration. Cacti are slow-growing plants and will rarely need repotting. Also, remember that many species of cacti will bloom better when they are slightly underpotted.
- For forest cactus, use a regular potting mix. Repot at the beginning of the growing season.
- In the spring and summer, when your desert cactus is actively growing and blooming or both, water whenever the compost begins to dry. During these waterings, make sure the plant is thoroughly watered. During the winter rest period, nearly cease watering. Only water if the plant begins to shrivel. The most common mistake with desert cacti is overwatering in the winter, which will cause rot either at the base of the plant or the tips of the growing areas. If the rot is advanced, it might be necessary to start new plants from cuttings or discard the whole plant.
- Water your forest cactus as a normal houseplant during the summer months and when the buds begin to show. During the resting period, only water when the soil is dry to the touch. As with succulents and desert cacti, forest cactus should not be watered heavily during the rest period. Root rot will result. Advanced root rot can only be treated by taking new cuttings and starting over.
Temperature and Humidity
- During the active growth period, desert cacti prefer hot, dry temperatures, ranging from 70 F to more than 80 F. In the winter, the plants prefer a cooler period, down to 55 F. In their desert habitats, many cacti are accustomed to very chilly nights. Do protect them from very cold winter drafts.
- Forest cacti are somewhat less picky about temperature; during the growing season, they have a wide range, from 55 F to 70 F. During the rest period, a colder spell of 50 F is essential.
- For desert cactus, use a cacti fertilizer during the growing season. Some growers have poor results with standard fertilizers, so it's probably worth it to seek out a specialized cacti fertilizer.
- For forest cactus, fertilize during the growing season with a standard fertilizer. Reduce fertilizer during the growing season.
All types of cactus can be prone to pests including mealybugs, scales, fungus gnats, and spider mites. In most cases, it's possible to simply wash these pests off of plants using cotton swabs and water.