Succulents are a popular choice with home gardeners for two simple reasons: They're beautiful to look and nearly indestructible.
To get technical, a succulent is any plant with thick, fleshy (succulent) water storage organs. Succulents store water in their leaves, stems, or roots. They've adapted to survive arid conditions found throughout the world, from Africa (where many of them are native to) to the deserts of North America.
This adaptive mechanism has resulted in an incredible variety of interesting leaf forms and plant shapes, including paddle leaves, tight rosettes, and bushy or trailing columns of teardrop leaves. As a group, succulents include some of the most well-known plants, such as the aloe and agave plants, as well as many nearly-unknown varietals found only in their natural environment. In addition, cacti are a unique subset of the succulent group and feature their own individual care and appearance.
No matter what kind of succulent you're growing, the rules are pretty similar among the different species. Here are the general rules for growing top-quality succulents.
Succulents prefer bright light when kept indoors or out, and should get at least six hours of sunlight a day. You can watch their leaves for an indication that the light exposure level you're giving them is correct—some species will scorch if suddenly exposed to too much direct sunlight, while others will have leaves that turn brown or white as the plant bleaches out and the soft tissues are destroyed.
On the other hand, an under-exposed succulent will begin to stretch, with an elongated stem and widely spaced leaves in a condition known as etiolation. The solution to this issue is to provide the plant with a better light source and prune the plant back to its original shape.
Succulents should be potted in a fast-draining mixture that's specifically designed for cacti and succulents. If you don't have access to a specialized mix, consider modifying a normal potting mix with an inorganic agent such as perlite to increase aeration and drainage.
You can also choose to pot your succulents in a terra cotta or clay planter to help with soil drainage. The porous nature of the materials will help to wick away moisture from the soil and help your succulents avoid root rot.
Succulents should be watered generously throughout the summer. Their potting mix should be allowed to dry out between waterings, but do not underwater. During the winter, when the plants go dormant, cut watering back to once every other month.
Overwatering (and the plant rot that can ensue) is the most common cause of succulent failure. An overwatered succulent might at first plump up and look very healthy, but the cause of death may have already set in underground, with rot spreading upward from it's root system.
Overwatered succulents are soft and discolored—their leaves may turn yellow or white and lose their color. A plant in this condition might be beyond repair, but you can still remove it from its pot and inspect the roots. If the roots are brown and rotted, cut away the dead roots and repot into drier potting media, or take a healthy cutting and propagate the parent plant.
Likewise, an under-watered plant will first stop growing and then begin to shed its leaves. Alternatively, the plant may develop brown spots on its leaves.
Temperature and Humidity
Succulents are much more cold-tolerant than many people realize. In the desert, where there is often a marked contrast between night and day, succulents thrive in the colder nights, where temperatures sometimes reach 40 degrees Fahrenheit or lower. Ideally, succulents prefer daytime temperatures between 70 degrees Fahrenheit and about 85 degrees Fahrenheit, and nighttime temperatures between 50 degrees Fahrenheit and 55 degrees Fahrenheit.
When it comes to humidity, not all succulents are created the same. Some prefer more humidity than others, but as a generally rule of thumb, they don't have an issue with humidity levels slightly above or below 80 percent humidity.
During the summer growing season, fertilize your succulents as you would your other houseplants. Stop fertilizing entirely during the winter.
Care of Non-Hardy Cacti and Succulents. Cornell Cooperative Extension.
Houseplant Diseases and Disorders. Clemson University Cooperative Extension.