Cacti
Scientific Name
Cactaceae
AKA
Cactus
Origins / Hardiness Zones
North America, South America / 9-11 USDA
About
Thousands of species of cactus plants exist in the wild, including two large groups of cacti grown as houseplants: desert cacti and forest cacti. Both groups thrive indoors with relatively little maintenance and come in many sizes, with small to moderate varieties being the most popular. Desert cacti typically bear spines or hair and are shaped like paddles, balls, or obelisks. Forest cacti hail from sub-tropical regions. They resemble other succulent plants, such as bromeliads, and grow in wooded areas of temperate forests and subtropical and tropical regions.
Light Needs
Water Schedule
Temperature
Humidity Levels
Toxicity
Cactus prefers humidity levels of 40 - 60%, which is fairly easy to achieve in most homes. Forest cacti like the air slightly more humid than desert varieties. So if you see your succulent plant wilting, mist it occasionally.
Cactus are not toxic if consumed, but their sharp spines make them hazardous to pets all the same.
Cacti require four to six hours of bright sunlight daily. However, some species of both desert and forest cactus can burn in direct sunlight. Locate your cactus near a sunny window, and opt for a spot that receives filtered bright light in the summer and direct light (like a south- or west-facing window) in the winter. You can move your cactus outdoors during the summer to provide ample light requirements, but do so only when night temperatures warm to 50 degrees Fahrenheit or above.
During the spring and summer, when your cactus is actively growing and blooming, give it a hearty drink every two-three weeks, allowing the water to drain thoroughly. During the winter rest period, decrease waterings to once every four weeks (and every six weeks for some desert species). The soil should be dry to the touch in between summer waterings and mostly dry in the winter.
Cactus prefers hot temperatures, ranging from 70°F to 80°F. In the winter, the plant prefers a cool-down period, with temperatures hovering near 55 °F. In its natural habitat, desert cactus is accustomed to very chilly nights and some species can even withstand nights that dip to 35°F. Still, any indoor plant that's not hardened off needs to be protected from winter drafts.
Symptoms of a pest include shriveled leaves, a mold-like coating, and the appearance of bugs on the stems or in the soil. In most cases, it's possible to carefully wash pests off using a spray from the sink hose or cotton swabs.
Overwatered cacti can suffer from fungal rot which looks like dark, sunken spots on the stem that eventually turn mushy. Remove the affected areas of the plant and treat it with a diluted hydrogen peroxide solution.
If your cactus produces offshoots (or pups), you can use them to propagate other plants. Most pups grow at the base of the plant, sharing nutrients and water from the mother plant, while others form along the stem or on the pads. Harvesting and propagating pups contributes to the health of the mother plant while allowing you to replicate the plant.
Cacti are slow-growing plants that will rarely need repotting. Actually, many species of cacti will bloom better when they are slightly root-bound. Cacti should be repotted at the beginning of the growing season only when they need fresh soil or are suffering from rot.
Cactus can survive some of the harshest conditions on earth. Any effort to fertilize is welcomed, but is not necessary. Some gardeners yield poor results with standard houseplant fertilizers (probably due to the improper ratio of nutrients), so seek out a specialized organic cacti fertilizer that contains more phosphorus than nitrogen. Fertilize your cactus two to three times a year, only during the growing season, and refer to the manufacturer's recommended amounts. Reduce or eliminate fertilizer during the winter.
The most common mistake cactus gardeners make is overwatering in the winter. This can lead to rot either at the base of the plant or at the tips where new growth appears. If the rot is advanced, it might be necessary to start a new plant from cuttings or discard the whole mother plant entirely.
The use of non-organic fertilizer can also damage your cactus because most chemical fertilizers contain heavy metals that eventually poison the plant. And because cacti have no protective bark or leaves, physical injury is common, causing a bump to lead to an infection. To prevent this, make sure to keep your plant healthy so that it will callus over before it becomes infected.
The most well-known decorative forest cactus is the Christmas cactus, which is native to Brazil, and blooms in red, pink, purple, and yellow. Both desert and forest cacti are slow-growing, boast beautiful blooms, and are among the sturdiest of all houseplants.
Repotting
Propagation
Pests / Diseases
Common Problems
Pro-Tip
Fertilizer
