How to Grow Cacti Indoors

A cactus is the perfect choice for anyone new to houseplants or for those who want the natural feeling and health benefits of indoor plants, but who simply don’t have a lot of spare time for plant care. Cacti are a low-maintenance, versatile group of plants. They’re great for growing indoors or out and their unusual, sculptural forms create a sense of décor as well as natural beauty.

What’s the Difference Between a Cactus and a Succulent?

A single plant is a “cactus”; two or more plants are “cacti”. All cacti are succulents, but not all succulent plants are cacti. The big thing that cacti and succulents have in common is they both have plant parts (leaves, stems and roots) that can store water in their tissue for long periods of time. The ability to store water allows cacti and succulents to succeed in sunny, dry locations such as deserts, steppes, or in the nooks of craggy rocks – areas where most other plants would fail.

The main difference between cacti and other succulents is a special structure found on cacti called an areole. Areoles are small round spots found on every cactus that produce tufts of small hairs and/or spines. While there are a few types of succulents that produce thorns, the thorns don’t emerge from areoles, and so they are not cacti.

You can have great success growing cacti in your home or office if you provide the right conditions. The keys are: enough light, a well-draining container and soil, and proper watering. Here are the six top tips for success with cacti:

Cacti can be grown in just about any kind of container from a coffee mug to a standard clay pot, as long as water can drain out the bottom. If you want to use an unconventional container for your cactus, you need to drill a drainage hole in the base (multiple holes if the container is large). Unglazed terracotta planters are especially good for cacti because of the porous nature of fired clay. Moisture can permeate the pot and evaporate away; reducing the risk of overwatering your cactus. You can create your own miniature desert garden by placing multiple plants in a large, shallow planter.

Cacti prefer a snug fit in their containers. When it’s time to repot, choose a container no more than an inch larger than the diameter of the root ball.

2. Light

Cacti grow best with at least 6 hours of sunlight per day. If possible, place your cacti by a south or west-facing window where they can get the maximum amount of natural light each day. For those with less than ideal situations you can help keep your cacti happier with artificial light.

Choose fluorescent or LED bulbs. They burn cooler and provide good energy efficiency. A daylight spectrum is best. What type of fixture depends on how many plants you have. Realize that plants directly under the light will get the most benefit so the more plants, then the more – or larger – fixtures you will need. The light doesn’t need to be any closer than a foot above the plant.

Just like people, cacti enjoy lounging in the summer sunshine. Your indoor cacti will benefit from a summer vacation out on the deck, a patio or balcony. Smaller, individual plants make a nice centerpiece on patio or end tables. Arrange larger potted cacti in a group together to create a desert scenario.

It’s best not to put your plants outdoors until the temperatures are consistently above 50°F (10°C). Transition your plants from indoors to outdoors by placing them in a shaded location first, then gradually moving them into more sun over the course of a couple of weeks. Just like people, if you place your cactus directly into full sun after a winter indoors, its delicate flesh can burn. Bring plants back indoors in early fall, before the danger of frost hits.

3. Water

Properly watering cacti is a case of “less is more”. The easiest way to damage or kill your cacti is by overwatering it. Try to keep it on a schedule by watering thoroughly (until the water runs out the drainage hole in the base of the pot) and then allow at least the top two inches of soil to dry before giving it a thorough watering again. To determine the right schedule for your plant, feel the soil. It should be thoroughly dry to the touch. Eventually you should figure out your plant’s water usage to the point that you can water it on a regular schedule. Never mist cacti. The moisture can pool up in the nooks of the plant and lead to rot.

Plants use the most water when they are actively growing so you will want to pay attention to seasonal light changes that affect plant growth. Your plant will probably dry out faster in the summer than in the lower-light days of winter, or even periods when there are many cloudy days in a row. Home heating can confuse matters because it dries the air and can, in turn, cause soil to dry out faster in the winter, even though the plants may not be actively growing. If, after you check the soil with your finger, you are unsure, hold off on watering for a couple days and then check the soil again. Remember, cacti are built for drought conditions. You are less likely to harm your plant if you let it get a little dry.

The simplest way to ensure that your plant has the right kind of soil is to purchase a potting mix specifically formulated for cacti and succulents. If you want to mix your own, a 1:1 blend of potting soil and perlite will do the job. Crushed pumice or gravel can be used with, or instead of perlite. Pure sand is not a good potting medium. It doesn’t provide any nutrition to the plant and can become so compacted over time that it blocks water drainage.

Select a fertilizer designed for cacti and succulents. Fertilizers can be found in several forms. Liquids are especially convenient to apply as well as slow-release granules. Whatever type you choose, be sure to follow the product directions for the correct application rate.

In winter continue to fertilize your plant only if it is actively growing. Depending on the light level, some plants may slow down or even stop growing in winter. That’s okay, growth will resume when the daylight hours grow longer again. You can resume feeding when the plant starts active growth again.

In general, cactus plants are happiest when temperatures remain above 50°F (10°C). Keep them out of cold drafts, away from doors in winter, and away from air conditioning vents in summer.

Cacti are susceptible to a variety of pests and diseases, however, the number one way to kill a cactus is by overwatering. Too much water, or a poorly draining pot, and the roots can start to rot. If not caught in time, the rot eventually moves throughout the plant. It is very difficult to save a cactus that has developed root rot.

If the flesh of your cactus looks healthy and firm but you’re seeing other problems, then you will want to inspect your plant for insect pests or determine if there has been physical damage such as bumping, scratches or bruising. Physical damage to a cactus can leave it permanently scarred, but it won’t necessarily affect the health of your plant. Cacti in nature are subject to all sorts of abuses from insects, birds, rodents, wind, and temperature extremes and are generally tough enough to survive. Learn more about common insect pests of houseplants here.

A variety of conditions might be required for your cactus to produce flowers, ranging from exposure to a specific number of hours of daylight, maturity of the plant, watering, and dormant periods that mimic the conditions found in nature. Many cacti require five or more years before they are mature enough to flower. It’s best to enjoy your cactus as a foliage plant and if you do happen to get flowers, consider it a happy bonus.

Cacti and Pets

When you have pets, it’s always best to research any plant you intend to keep indoors. Start your research with the ASPCA’s list of Toxic and Non-Toxic Plants. It’s a list of many common plants that can harm your cat, dog, or other domestic animals. If you don’t see your plant listed there, then try a general search online or perhaps check with a veterinarian just to be sure.

Cacti are generally not toxic to cats and dogs; however, animals are curious creatures and sometimes accidents just happen. It can be very difficult to remove cactus spines from a pet’s nose or other body part after a mishap with a cactus. Any spines left behind in the skin have the potential to become irritated and infected, so consider this before adding cacti to your houseplant collection or deciding where to locate plants in your home.

Cacti Planted in Glued Rocks

Its common these days to find individual cacti, succulents, and dish
gardens for sale that are potted with a rigid material made from glued rocks
covering the soil surface. This material holds the plants snug and makes it easier to ship them without worry that the plants will become dislodged while in transit.

If you would like to remove your plant from the rocks, start by putting on a pair of protective gloves so that you don’t get cactus spines in your fingers. Run a thin, blunt tool around the inner rim of the pot; between the rocks and the side of the pot. You could use a flat-head screwdriver, knife, or other flat utensil (we don’t recommend sharp tools because we don’t want you to cut yourself). Once all the gravel is loosened from the side of the pot you should be able to lift the plant out of the container and break away the glued gravel. If it doesn’t break easily try using a pair of needle-nose pliers, taking care that you don’t gouge the plant or roots. Once the gravel is removed you can repot the plant as you would normally.

Looking for other plants that would make good companions to your cactus? Click here to discover more great houseplants.