University of Illinois Extension

Cacti and Succulents as Houseplants

If you want to invite a wide and varied bunch of plants into your home, you might consider cacti and succulents, said Greg Stack, a University of Illinois Extension horticulturist.

“Many of these unusual plants are quite content with most home conditions and occasional neglect, asking nothing more than a bright, sunny location,” said Stack. “In return, they will give you interesting shapes, varied patterns of spines, and some really beautiful flowers.”

For starters, it is important to know the difference between a cactus and a succulent, he noted.

“All cacti are succulents, but not all succulents are cacti,” he said. “ That statement alone will make people wonder if maybe you’ve been reading too many gardening magazines.  But there is a difference. While both cacti and succulents have the ability to store moisture for use when times are tough, that is where the similarity ends.

“A true cactus has something called an areole. It looks like a patch of cotton from which spines, flowers, and roots grow. While some succulents may have spines, they will not have areoles.”

Many places sell succulent plants. Following a few buying tips can ensure getting the best, he said.

“Check the base of the plants for signs of softness,” said Stack. “This indicates a rotting problem and a plant not long for the world.  Avoid plants where the new growth is thin and pale in color. This suggests plants that have been kept in poor light conditions for too long. And always check for insects, especially scale and mealy bug.”

Once the plants are in your home, a few basic growing conditions need to be met to ensure happy and healthy plants.

“All cacti and succulents need bright light areas,” he said. “If the light is too low, they will often stretch and even round, barrel-shaped cactus will become very thin and elongated.

“Cacti and succulents have growth cycles, and it is usually in response to water and temperature. At one time of the year when temperatures are cool and moisture low, succulents will go dormant. When temperatures are warm and moisture more abundant, succulents grow more actively.”

Most cacti and succulents have their active growth cycle during the spring and summer, gradually slowing down and going dormant in the fall and winter. Plants with this growth cycle include the Echinocactus, Ferocactus, Opuntia, and Notocacus.

“These plants should be kept warm and well-watered during the natural growth cycle and cool and dry at other times of the year,” Stack said. “The more succulent tree dwellers such as Christmas cactus prefer warm temperatures and moist soils during the late spring and summer and cool temperatures and dry soil for several months before their yearly blooming.”

Temperature is an important factor for cacti and succulents. Providing the proper temperature can often result in encouraging the cacti and succulents to bloom. Proper temperature is dependent on whether the plant is growing or dormant.

“Dormant plants prefer temperatures between 45 and 55 degrees,” said Stack. “These cool temperatures combined with occasional light watering ‘hardens’ the plant. Flower buds are more likely to form at the cooler temperatures.

“Many cacti, particularly the globe-shaped ones, will bloom readily if given this cool, dry period. Areas right next to windows often provide the perfect growing environment during the winter and can satisfy the cool temperature requirement. Growing at normal room temperatures will by no means harm the plant but if you want to see flowers, cold helps.”

During the summer, cacti and succulents like to be outdoors. Locate them where they get light shade and keep them watered.

“Even though cacti and succulents can tolerate dry conditions for extended periods, they do like to receive water for best growth,” he noted. “Watering is based first of all on whether they are dormant or growing. During the growing period, water the plants thoroughly when the soil gets dry and don’t let them sit in a saucer of water.

“Water again only when the soil gets dry. During the dormant period, apply water very sparingly. Let the soil get dry and then apply enough water to slightly dampen the soil. Overwatering during the dormant period can lead to rotting.”

Stack recommended a few cacti as good starter plants. These are easy to maintain and often will flower.

The Mammillarias, or pin cushion, cactus is perhaps the most commonly sold. They form nice clumps and have silky hairs covering the body of the plant and have names such as owl’s eyes, birdnest cactus, old lady cactus, and feather cactus. They are easily grown and will flower readily when young, producing white to pink flowers in a circle around the top of the plant.

“Another group of reliable cactus is the Notocactus,” he said. “These also form clumps or nice ball-shaped plants. They are reliable bloomers at a young age. Look for such names as Sun Cap, Silver Bell, and Scarlet Ball.

Aeoniums are succulents that grow in the form of flat pinwheels. They can be green, bronze, or silver in color and are very architectural looking. In nature, they grow during the winter, but indoors may switch to summer growing. Watch for signs of dormancy by a closing and shrinking of the leafy rosette.” 

One of the more challenging but truly unique succulents is the Lithops or living stones. In nature, they grow submerged in the soil with only their tops exposed, looking just like pebbles. Allow the soil to dry completely between infrequent light watering during their summer dormant period.  In the fall and winter, water the plant more frequently but still maintain the soil on the dry side. The frequent reward for this care is daisy-like flowers in November or December appearing in what looks like a crack in a rock.

“Cacti and succulents can be the almost perfect houseplants--asking little but offering much in way of interest,” said Stack.