There are two main groups of indoor cactus grown as houseplants: the desert cacti and the forest cacti. Indoor cactus plants come in a wide variety of shapes and sizes, but most are easy to grow provided their care needs are met.
Indoor Cactus Appearance
Desert cacti are the type most associated with a typical cactus shape and behavior. These cactus house plants often have spines or hairs that prick the skin when touched. Shapes vary from paddles, balls, or obelisk with most producing flowers under the right conditions.
Forest indoor cactus are tropical or subtropical plants with atypical cactus shape or growing patterns. Some are climbers or epiphytic, meaning they grow up the length of trees in their native habitat. The Christmas cactus is an example of this type of indoor cactus plant.
Indoor Cactus Lighting Needs
Indoor cactus plants prefer bright, indirect sunlight of between four and six hours per day in the spring and summer. Unlike the outdoor, desert varieties, prolonged exposure to full sun results in burning or scarring of their surface. Direct sunlight in the cooler, winter months is acceptable and plants will thrive in a south or west-facing window.
Cactus House Plants Water Requirements
Most Indoor cactus plants are drought tolerant, but still require regular watering in the spring and summer growth months. Water at least once per month if the indoor cactus lives in a warm, bright location. Insert a stick into the pot’s soil and, if it comes out dry, it is time to water. Moisten the soil to the roots but do not let the soil become soggy as this leads to root rot. Taper off the watering schedule beginning in fall and provide water only once every four to six weeks in the winter to allow the plant to go dormant.
Soil and Fertilizer
All indoor cactus plants require fast-draining soil to avoid becoming waterlogged. Use a potting soil designed for cacti or mix your own by amending houseplant potting soil with sand, pebbles, or perlite for drainage. Forest cacti are more soil-tolerant and will grow in regular potting soil but add peat moss to the soil to retain moisture, making up for their lack of water-storing ability.
Fertilize your cactus house plant during the spring and summer to encourage vigorous growth and flowering. Use organic fertilizer, such as fish emulsion, added to the soil for a slow-release feeding. A synthetic fertilizer, such as 10-10-10 or 5-10-10, diluted to ½ strength also works. Feed two to three times during the growing season only, avoiding fertilizer in the dormant winter months.
Indoor Cactus Pruning and Propagation
Most indoor cactus plants only require pruning to remove damaged or dead areas or to control size. Always use sharp, sterilized garden shears or a knife and wear thick, protective gloves to avoid injury from spikes or toxic sap.
Propagation of cactus house plants is easiest by cuttings. Follow the same sterilization and safety procedures as with pruning. Cut the offshoots, called pups, at a 45 degree angle to allow the wound to callus. Let cuttings sit in a dry place for up to 7 days prior to repotting.
Indoor Cactus Varieties
The Rat Tail Cactus
The Rat Tail cactus is a low-maintenance, indoor cactus plant producing orchid-like blooms in the spring or early summer. The stems are bright green when healthy, covered with bristly hairs and brown thorns. Stems reach a length of up to 5 feet and their long tubular shape resembles the tail of a rat. This indoor cactus plant prefers bright, indirect light from a south or west-facing window all year long. Once temperatures at night reach a minimum of 50 degrees Fahrenheit (10 degrees Celsius) but avoid full-sun exposure.
Water the rat tail cactus house plant to keep the soil moist, but not soggy, during spring and summer. In winter, decrease watering to only when the soil has become dry, then water lightly. Grow this indoor cactus plant in a hanging basket to best accommodate its trailing growth pattern. Line the basket with sphagnum moss to help retain moisture and amend the potting soil with sand or perlite if not using a cactus-specific soil mixture.
Repot the rail tail cactus once per year to accommodate its fast growth and need for new, nutrient-rich soil. Wait until flowering is complete before repotting. Prune the plant to remove dead or diseased stems. Deadhead expired flowers once blooming is finished, wearing protective gloves.
African Milk Tree
The African Milk Tree is technically a succulent, not a cactus, but its growth pattern resembles that of typically desert cacti. The plant has a fast growth rate of 1 to 2 feet (30 to 60 cm) per year and is used as an outdoor hedge in suitable climates. Each triangular stem features three distinct sides separated by raised ridges. Teardrop-shaped leaves emerge from the stems along with thorns. It grows to a height of 9 feet (2.7 meters) outdoors but growth is typically half when grown as a houseplant. The plant prefers bright, indirect light from a south-facing window.
Like a cactus house plant, water the African Milk Tree once per week in the spring and summer. Moisten the soil to the roots, but do not let the soil become soggy. Allow the soil to dry between waterings, using an inserted stick to check for moisture presence. Reduce watering to once per month in the fall and winter. Grow this succulent in a well-draining potting soil amended with perlite for added drainage.
Fertilize in the spring and summer, once per month, with a water-soluble fertilizer diluted to ½ strength. The plant prefers temperatures above 55 degrees Fahrenheit (13 degrees Celsius) but does not require high humidity as it leaves the plant vulnerable to pests and disease.
Barrel Cactus
The Barrel cactus is ball shaped when young but lengthens, turning into an oval shape, as the plant matures. This indoor cactus features rows of spines evenly spaced on pronounced, ribbed lobes. When grown as cactus houseplants, they rarely bloom indoors unless conditions are prime. The blooms are yellow and appear in spring or summer at the top of the cactus. Grow the Barrel cactus in full sun near a south-facing, sunny window.
Water this indoor cactus once every two weeks during the spring and summer. In the fall, taper off watering to once every four weeks. Do no water in the winter to mimic the cacti’s natural dormancy period. As spring approaches, slowly increase watering to once per month, then follow the spring and summer watering schedule. Always allow the soil to dry completely between watering. This cactus house plant requires a well-draining soil. Use either a cactus soil mix or combine a peat-based soil with sand or perlite to improve drainage.
Provide temperatures between 50 to 80 degrees Fahrenheit (10 to 27 degrees Celsius) in a dry environment with no added humidity. Avoid placing your plant near vents, humidifiers, or in bathrooms with high humidity.
Bishop’s Cap
The Bishop’s Cap indoor cactus is a spineless variety of cacti that starts out with a round shape. As the cactus matures it develops four to eight ribs giving it a bulbous, star shape. This cactus house plant blooms more readily than other cacti indoors and produces yellow flowers resembling daisies. As the plant matures, it’s natural for it to form white, hairy scales. Protect young plants from full sun, providing the cacti with filtered light or light shade. Mature plants are more tolerant of sun but never full sun.
Give light waterings once every two weeks, or when the soil feels dry, during the spring and summer. Taper off waterings beginning in the fall when temperatures cool. Do not water in the winter months to allow the plant to go dormant. Slowly introduce water again in the spring. Grow Bishop’s Cap in either a cactus soil or by creating a mixture of 25% coarse sand, 25% pumice, and 50% potting soil.
The Bishop’s Cap indoor cactus prefers temperatures around 70 degrees Fahrenheit (21 degrees Celsius)in the spring and summer. Reduce temperatures to around 40 degrees Fahrenheit (4 degrees Celsius) in the winter to discourage infestations of mealybugs or scale.
Peanut Cactus
The Peanut Cactus gets its name from the finger-shaped stems it produces in clusters. Each stem grows up to 6 inches in length and ½ an inch in diameter and is covered in small, white bristles. This indoor cactus produces orange or red blooms in late spring to early summer. These indoor cactus plants prefer bright sun exposure from a south or west-facing window. The plant does not tolerate low lighting.
The Peanut Cactus is a drought-tolerant indoor cactus due to its fleshy, water-storing stems. Allow soil to dry completely between waterings to avoid root rot. Soak the soil when watering in the spring and summer, avoiding pouring water directly onto the cactus. Reduce water in the winter to once per month at most. Use a cactus or succulent soil to grow this cactus house plant or amend potting soil with coarse sand and perlite to improve drainage.
Average household temperatures and humidity are acceptable for this indoor cactus. It does not tolerate high humidity and the use of a dehumidifier is needed for humid conditions. In the winter mimic the cacti’s natural dormancy by providing temperatures of between 32 to 44 degrees Fahrenheit ( 0 to 7 degrees Celsuis). The lower temperatures encourage blooming the following spring.
Fairy Castle Cactus
The Fairy Castle Cactus reaches a height of 6 feet (2 meters) at maturity. This indoor cactus gets its name from the multiple stems it produces at varying lengths that resemble the turrets and spires of a castle. Each stem is five-sided with wooly spines on each plane. Blooming indoors is rare and often does not occur until the cactus is 10 years or older. Flowers are white or yellow and appear at night. This cactus house plant prefers full sun but tolerates partial shade. Too little light exposure causes faded color and misshapen columns.
Water this indoor cactus once the soil is dry. Let the water seep through the soil until it runs out the pot’s drainage holes. If a drip tray is used, pour out excess water collected to avoid root rot. Use a soil mixture that is well-draining such as cactus soil or a peat-based potting soil amended with coarse sand or perlite.
The Fairy Castle Cactus prefers high temperatures and is not frost tolerant. No added humidity is required. Avoid placing this indoor cactus plant near vents or air conditioning as it will stunt growth. To encourage growth, feed once per month with a cactus fertilizer or dilute the fertilizer in water and feed during waterings.
Lady Finger Cactus
The Lady Finger Cactus gets its name from the stems resemblance to fingers. Each stem grows up to 8 inches (20 cm) tall and 1.2 inches ( 3 cm) in diameter. The tubes are bright green with yellow or golden-colored spines protruding. Blooms appear in early spring with colors of white, pale yellow, or bright pink. Flowers grow from the upper portion of the stems. Provide this indoor cactus with up to 6 hours of direct sunlight per day for mature plants. Young plants are less sun tolerant and thrive with indirect light or partial shade.
Water is stored in this cactus house plant stems so watering sparingly. Allow the soil to dry between watering and provide enough water to evenly moisten the soil but not become soggy. Decrease watering in the fall and refrain from watering during the dormant winter months. The soil for these indoor cactus plants requires a fast-draining mix of potting soil amended with sand or perlite or a cactus mix. Add a layer of fine gravel to the bottom of the pot, before adding the soil, to improve drainage.
Average household temperatures and humidity are suitable for the Lady Finger Cactus. Avoid temperatures below 20 degrees Fahrenheit ( -4 degrees Celsuis) as the plant is not frost tolerant. Cooler temperatures during winter encourage blooming in the spring.
Lamb’s Tail
The Lamb’s Tail is technically a succulent with a trailing growth pattern suitable for hanging baskets. Each stem grows to a length of between 2 to 4 feet ( 0.6 to 1.2 meters) with tear-drop shaped leaves. The plant will grow to a width of 1 to 2 feet wide ( 0.3 to 0.6 meters). Blooming when grown indoors is rare. Lamb’s Tail prefers a sunny location near a bright window with several hours of direct sunlight per day. Too much sun exposure, especially if grown outdoors, will scorch the delicate leaves.
Similar to indoor cactus, Lamb’s Tail is drought tolerant and stores water in its leaves. Water the plant heavily once per month, allowing the soil to dry between waterings. Taper off frequency of water in the fall and winter. If in doubt, do not water as the plant is susceptible to root rot. Grow the plant in a well-draining, sandy soil such as a mix for cacti or succulents. Potting soil amended with sand is also acceptable.
Keep temperatures between 65 to 75 degrees Fahrenheit ( 18 to 24 degrees Celsuis). Lamb’s tail will tolerate short exposure to temperatures of 40 degrees Fahrenheit ( 4 degrees Celsius) but is not frost tolerant. Avoid excessive humidity levels and do not mist the leaves or place it in a bathroom.
Dinosaur Back Plant
The Dinosaur Back Plant is grown as both an indoor cactus and outdoor plant. It reaches a height of 12 inches (30.5 cm) tall and 36 inches ( 91 cm) wide. It features blue-gray trunks that fan out and form overlapping clusters. The branches are thick and waxy, resembling the skin of a dinosaur, and sport a few long thorns protruding from the surface. This cactus house plant produces small, cream-colored flowers in the summer. Mature indoor plants prefer full sunlight from a south or east-facing window. Younger plants require some sun protection with filtered light but not total shade as it inhibits growth.
Follow the soak and dry method for watering this indoor cactus plant. Allow the soil to dry out between waterings, then water until it runs out the pot’s drainage holes. Water most often in the spring and summer growth months, tapering off beginning in the fall. Do not provide water in the winter to allow the plant to go dormant, which promotes blooms next summer. Grow the Dinosaur Back Plant in a well-draining cactus soil or potting soil amended with pumice, gravel, or perlite for drainage.
Optimal growth occurs in temperatures above 50 degrees Fahrenheit ( 10 degrees Celsius). Cooler temperatures below 25 degrees Fahrenheit ( 4 degrees Celsius) affect the plant’s appearance and growth.
Lifesaver Cactus
The Lifesaver Cactus is a small indoor cactus prized for its unique blooms resembling Lifesaver candies. The flowers feature a raised, shiny center surrounded by a corolla with red and cream-colored stripes. The green stems of this cactus house plant are tubular shaped with distinct ridges, edged with soft spikes. While the blooms are magnificent to look at, their aroma is less than inviting. It is described as giving the scent of rotting meat, which attracts pollinators in its native habitat. Partial sun is best for the Lifesaver Cactus from an east or west-facing window. Too much sun exposure causes the green stems to turn red.
Water this indoor cactus plant, when the top 1 inch of soil feels dry when a finger is inserted, during spring and summer. Pour the water slowly until it runs out the drainage holes of the pot, then empty the drip tray of excess water. Taper off watering in the fall, when the weather cools. During the winter water no more than once per month. Provide a well-draining cactus or succulent soil mix that includes both organic and inorganic matter.
Fertilize your indoor cactus once per month beginning in the spring. Use a liquid succulent plant food or a complete, granular fertilizer diluted to half strength. Stop feedings in late summer to allow the plant to go dormant for the winter months.
The Candelabra Tree
The Candelabra Tree is often an outdoor plant, but can be grown as an indoor cactus as well. It grows to a height of between 36 to 49 feet (12 to 15 meters) in the wild but will mature much smaller when grown as a houseplant. This cactus features several stems with spikes protruding from the surface. Blooming occurs in fall and winter with greenish-yellow flowers. Place your Candelabra Tree in full sun near a south-facing window for optimal growth. An east or west-facing window will also suffice.
As with many cacti, this indoor cactus plant stores water in its stems, making it drought tolerant. Water in the spring and summer once every two weeks or when the soil dries out completely. In the fall decrease watering, reducing winter waterings to occasional or none until early spring. Grow this cactus in a well-draining soil of two parts coarse sand, one part peat moss, and one part loam.
The Candelabra Tree is a light feeder requiring a 10-10-10 NPK fertilizer, diluted to half strength, once in the spring. Please note the milky, latex-based sap of this cactus is both poisonous and a strong irritant. Keep this plant away from children and pets, and do not allow contact with its sap.
The Moon Cactus
The Moon Cactus is a grafted specimen consisting of two separate cacti. The lower “host” cactus can be a number of species, but is often the Hylocereus cactus. The top “scion” is Gymnocalycium mihanovichii. The scion cactus is the most eye-catching with a color of red, orange, or yellow atop the green host. Blooming occurs in the summer with yellowish-green flowers. Provide bright, indirect light for this indoor cactus to accommodate the differing sunlight preferences of the host and scion. Too much direct sunlight will fade the scion’s bright colors.
Allow the soil to dry between waterings of this cactus house plant, then water until soil is well moistened. Cacti in small plants require watering once per week. Do not allow water to stand in the drip tray as this leads to root rot. In the winter withhold waterings, opting for occasional misting instead. Use a well-draining cactus soil mix with a low pH.
Feed the Moon Cactus once per month in the spring and summer with a fertilizer designed for cacti. Withhold feedings in the winter to allow the plant to go dormant, which encourages blooming next season.
For cacti lovers there is a wide variety of beautiful and unique cactus house plants to collect and care for. Most are low maintenance and resistant to drought. Cacti are often resistant to pests and disease providing their simple care needs are followed. The indoor cactus makes a wonderful houseplant for both novice and experienced plant lovers.
Indoor Cactus FAQ
Yes, all types of cacti require some degree of sunlight to thrive. Some prefer full sun, while others need only filtered sunlight.
Most cactus house plants will do well when placed outside in the summer months. Be cautious of placing them in full sun as it may damage their exterior. Bring them in once temperatures begin to cool at night.
Most varieties of cacti bloom in the spring or summer. Not all cacti will bloom indoors.
Too much water is often the cause of a cactus turning white. Decrease watering frequency and ensure the environment does not have high humidity.
The most common causes for failing indoor cactus plants is too much water or incorrect light exposure. Provide water only when the soil dries out and decrease waterings in the winter months. Bright, indirect sunlight is best, though some varieties prefer more direct sun.
