A little bit of water, a lot of sun and a striking texture that catches the eye? Cacti might not be the first idea that come to mind for a houseplant, but they can be conversation starters indoors and long-lasting features in landscaping projects outdoors. Knowing the basic needs of your cactus will help keep it alive and thriving.
Common Types of Cactus
There are around 2,000 types of cactus growing around the world, and only four of those cacti are not native to the Americas. Cacti fall into two groups: desert cacti and forest cacti. Most common are desert varieties, but the popular "holiday cactus" group (USDA zones 10-12) - Thanksgiving cactus (Schlumbergera truncata, Christmas cactus (Schlumbergera russelliana, formerly S. bridgesii), and Easter cactus (Schlumbergera gaertneri) - are three of the forest cacti that can be found in home and garden centers. Hot, dry climates such as the North American Southwest and Mexico are home to desert cacti.
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The stereotype cactus depicted in media like cartoons and old Western films is the saguaro (Carnegiea gigantea, USDA zones 9-11). Its form consists of barreled branches that extend upward like arms. The saguaro can grow up to 60 feet tall and live for 200 years. It is in danger of being wiped out, and conservation efforts are being made by state parks to preserve the plant. The saguaro is in the same family as the organ pipe cactus (Stenocereus thurberi, USDA zones 10-11) and barrel cactus (numerous genera and species), all sharing similar looks. This cactus is found on gravelly slopes and rocky ridges in the lower Sonoran zone that runs from northern Arizona to Sonora, Mexico. It can also be found in California and along the Colorado river, growing where it is hot and dry.
Along with their Latin names, cacti have nicknames that often describe their shape and features. Fish hook (Sclerocactus spp., USDA zones 10-11) and prickly pear cactus (Opuntia spp., USDA zones 3-9, depending on species and cultivar) are great examples. More common varieties, like red cap cactus, also called a ruby ball cactus for its obvious red flowered top (Gymnocalycium mihanovichii, USDA zones 11-12), the bunny ears cactus (Opuntia microdasys, USDA zones 9-12), pincushion cactus (Mammillaria spp., USDA zones 8-11, depending on species), and hedgehog and rainbow cactus (Echinocereus spp., USDA 9-11), can live indoors with access to light and are popular choices for house plants.
Cactus Life Cycle
Depending on the cactus species, the life span of cacti can reach 200 years. Flowering and fruit cacti produce seeds, with some producing a million seeds to spread. They are categorized as angiosperms and have both male and female parts for reproduction. Generally, cacti grow slower than other flowering plants, but their life cycle and means of pollination are largely the same. If you properly care for your cactus, it may outlive you!
Cacti vs. Succulents
Every cactus is a succulent, but not all succulents are cacti. The difference lies in the small round area where spines and flowers can grow from a cactus, called an areole. This signifies the plant as a cactus. Some succulents have it; some do not. Succulents are any plants that store water in their stems or leaves. Cacti store water, making them part of the succulent family.
Necessities to Survive: Bright Light
Cacti love sunlight. The more sunlight, the better. They are built for a hot desert blaze and need as much sunlight as possible when living indoors. In winter months, make sure your indoor cacti are in the brightest spot possible.
Tropical and desert plants don't like the cold. The best climate for cacti is somewhere between 40 and 90 degrees Fahrenheit. Desert temperatures can fall at night, so most cacti are built to stand colder temperatures for a short period of time. If the temperature drops below 35 degrees, it's time to move your plant to a warmer environment.
Contrary to popular belief, cacti need regular watering. More important, they need proper drainage. All cacti need to be watered deeply during the hottest months, but the roots should never be waterlogged, and the soil shouldn't stay wet. Cacti stems swell when they are storing water. Cacti are dormant in winter, especially those that enjoy outdoor living. Colder months will not need as much watering. If your plant is a little smaller in winter months, it's just waiting for summer. Watering your cactus in cold temperatures can damage or kill your plant, because the stored water inside the plant (perfectly built for droughts) can freeze, harming your plant from within. Overwatering can kill cacti as well – it's better to under than overwater this spiky plant.
The right soil is essential for cacti. A desert cactus has a natural environment of sandy, coarse soil that does not remain damp after a rain storm. Mimic this in potted cacti with a specialized mix made for succulents and cactus or a mix of sand, perlite (volcanic glass used to lighten soil) and potting soil. Succulent and cactus soil can be found at home improvement stores and gardening centers.