There are many species of aloes that are marginally cold tolerant. In Tucson, these can be grown with minimal frost protection, but only one kind will reliably survive temperatures in the mid to low 20s. Aloe aristata has been tested to at least 11°F with no protection and survived nicely. It is a low clumping species with thin, dark green leaves. The flowers are reddish and show up nicely against the darker foliage. Light shade is best, and the plant reaches a width of 15-18” with age.
Several of the other less cold-hardy aloes can be used effectively in your landscape. The trick to growing these is placement. To thrive in Tucson, most aloes prefer some summer shade. Plant your aloe under the canopy of a tree (or a shrub for the smaller species) for best results. A canopy also doubles in the winter as minimal frost protection, and this is usually enough protection for many aloes.
Some of the larger aloes to use here include Aloe ferox, Aloe marlothii, Aloe candelbrum, Aloe rupestris, Aloe africana, Aloe excelsa, and Aloe spectabilis. These can attain a height of 6-8’ with a spread of 3-4’. The all have incredibly beautiful flowers borne on stalks several feet above the plant, and range in color from yellow to orange to red, occurring in late winter and early spring.
In addition, many low-growing species of aloe do well here in Tucson. These include Aloe karasbergensis, with beautifully striated leaves and coral colored flowers; Aloe humilis, a small clumping species with reddish flowers; Aloe variegata, with short, thick leaves and many salmon colored flowers; and Aloe broomii, the Agave look-alike of the aloes. Others to look for are Aloe claviflora, Aloe divaricata, Aloe gariepensis, Aloe microstigma, Aloe parvula, Aloe peglare, Aloe praetensis, Aloe prinslooii, and Aloe vacillans.
The growing season for aloes is our cool season. Once a week watering from fall through spring is best, tapering to once every two weeks in the summer. Aloes can be successfully grown in either pots or planted in the ground.
Did You Know? All Aloes are native to Africa. However, Aloe barbadensis is the true Aloe Vera.