Aloe (Aloe spp.)plants, hardy in U.S. Department of Agriculture plant hardiness zones 10 through 12, make perfect houseplants for the lazy gardener. They thrive in the same temperatures humans do and tolerate the arid conditions central heating creates. This undemanding genus contains hundreds of species, some growing in tight little rosettes and others with thick, lance-shaped leaves.
Aloe for Indoors
Aloes exist that are small enough to grow on a windowsill (Aloe aristata) or in a treelike form to fill a corner of a room (Aloe plicatilis) with its fan-shaped foliage. There's even an aloe that grows as a vine (Aloe arenicola). Typically, though, the beginner's houseplant will feature the spiky-edged, thick, lance-shaped green leaves, occasionally mottled with gray-green of Aloe vera (Aloe barbadensis). Its thick leaves hold a white sap and clear juice that may cause digestive upset or even diarrhea if enough is ingested.
The aloe is a succulent, evolving with thick flesh and short roots to protect it against heat and snatch up rain before it filters downward through the sandy soil. Give aloes plenty of light and an even mix of potting soil, sharp sand and peat -- often marketed as cactus soil -- to avoid holding too much moisture and causing root or crown rot.
Aloes grow in full sun, but place them in a bright sun porch or south-facing room outdoors -- in full sun, they can develop unattractive bronze spots. Protect them from rain outdoors, too. Water aloes only when the soil is dry and always plant them in a pot with drainage holes.
Aloes do not tolerate freezing weather, so wait several weeks after the last frost to take plants outdoors. Bring outside plants indoors when night-time temperatures begin to fall below 50 degrees Fahrenheit in autumn.
Food and Propagation
Because they are desert dwellers, aloes receive most of their nutrition from rainfall and deposits made by passing animals. Their needs lessen during the winter, so decrease watering in winter and withhold fertilizer altogether. Plants may benefit from a spring application of a half-strength solution of a 10-40-10 houseplant fertilizer. If instructions say to add a tablespoon to a gallon of water, use only a half-tablespoon. Just water the plant until water runs out the bottom of the pot.
Aloe vera and many other species reproduce by seed and offsets, called pups. The fastest way to reproduce an accurate clone of the parent is to root offsets. Snip the thick stolon that connects a pup that has grown 2 or more inches tall and plant it in its own pot, leaving the cut end above the soil to dry. Do not fertilize new plants for at least four months.
Pests and Problems
Among the traits that make aloes good house guests is their resistance, thanks to their thick skins, to many typical houseplant problems. Root and crown rot, thanks to overwatering, is their main disease threat.
Occasionally, especially when they've been outdoors to summer camp, plants might host mealybugs or scale. Remove pests with a firm spray of water. Sprays such as insecticidal soap or Neem oil prepared for indoor use are also effective controls.
Always treat bugs as far away as possible from other plants, preferably outdoors before bringing them indoors.
Remove aloe pups every other year to allow the parent to continue to grow larger without requiring a larger pot.