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Growing Succulents in the Desert Column

(List of Growing Succulents in the Desert columns)

Growing Aloes in the Arid Southwest by Gene Joseph

(This article may only be reprinted with the author's permission.)

The genus Aloe contains a good number of species that can be grown here in the arid southwest, enhancing the landscape with interesting leaf colors and markings, striking forms and silhouettes and in almost every case, beautiful flowers. The aloes that perform best here are generally those from South Africa and Namibia and the Arabian peninsula. These plants are more heat tolerant than aloes native to the more tropicalareas and those from the cooler winter rainfall areas. Our climate is hotter than those from where aloes originate. Because of this, it is best to plant them where they get mid to late afternoon shade in the summer. Aloes are mostly cool season growers though, so they can take full sun throughout the day in winter. This is actually easy to accomplish. Planting on the east side of a tree, shrub or wall will work, but the best location is to plant aloes just under the south canopy of a tree. In this case when the sun is high in summer, the plant is in the shade and in winter, with the lowering sun, the planted aloe will receive full sun. Aloes grow well in containers, but are somewhat more sensitive to heat when potted, so placement is very important. The roots of aloes, both in the ground and in containers, are sensitive to overheating and if this occurs will start to rot. Besides placement, another thing that will help mitigate the heat is to plant something green, preferably a summer grower, around the base of the aloe. This should be something that will do well with minimal, shallow waterings throughout the hot summer. Some examples of this are Salvia spps., Manfreda spps., Stapelia spps., Crassula spps. (summer tolerant only!), etc.. This root/heat problem is more of a problem for the taller growing aloes than the clumping types.
There are basically three types of aloes in growth form that grow well here in the low deserts; tree aloes, clumping stemless aloes and single (or limited clumping) stemless aloes. The tree type species includes A. dichotoma, A. ramosissima, A. marlothii, A. ferox, A. speciosa, A. africana, A. excelsa, A. candelabrum, A. rupestris, A.alooides, A. castenea. Most of these tree aloes will grow to many feet tall (5 to 10) with a spread of several feet. Aloe dichotoma with some protection will grow to 25 feet. Also, the tree aloes have some of the most dramatic and beautiful flowers of all. The inflorescence can be several feet tall and across and the colors can range from yellow to orange to a spectacular red. Most of these species, however, are not color specific, so the flowers can be different on individuals within a species. These aloes are significant accent plants in the garden. Give them a place of prominence, planting them amongst rocks and plant lower, spreading plants at their base.

The stemless clumping type includes A. greenii, A. variegata, A. glauca, A. aristata (cold tolerant to mid teens!), A. nobilis, A. parvula, A. vera (A. barbadensis), A. fosteri, A. sapinaria (very common in older landscapes), A. longistyla, A. sinkatana, A. humilis, A. vacillans, A. globuligemma, A. mudenensis, A. suprafoliata, A. brevifolia. These aloes are grown for their colors and textures and also their flowers, which range in color from whitish to yellow to salmon to red. These plants are best used as spreading mass plantings amongst other plants, at the base of tree aloes and along walls, walkways and together with rocks.

The third basic aloe form is the stemless, mostly single rosette, which includes, A. broomii, A. hereroensis, A. peglare, A. praetensis, A. tomentosa, A. striata, A. karasbergensis, A. lutescens, A. claviflora, A. cryptopoda, A. gariepensis, A. krapohliana, A. melanacantha, A. microstigma, A. prinslooii, A. petricola, A. reitzii. The species in this group are accent plants and look best (and seem to grow best) when planted in a rock garden type of landscape. Their appeal is mostly their distinctive leaf colors, shapes and of course flowers.

With the exception of Aloe aristata, which is cold tolerant to the mid teens, most of the previously listed aloes will need protection from temperatures in the mid twenties. This can be mostly accomplished by placement. If the aloes are planted under a tree, this will in most cases, give enough cold protection to keep them from freezing. Planting next to a large rock will work as well, as the rock will give off heat throughout the night keeping the plant from freezing. Another action, and a very effective one, is to cover the plant with frost cloth. Using the modern, light weight material over the top of the plant can effect 5 to 10 degrees of cold protection. (Keep a piece near the plant, cut to size and marked with the plant’s name, ready to throw onto the plant at the end of the evening.

During the cool season, most aloes should be watered weekly for optimum growth and appearance. In the hot summer, water them weekly as well, but with a reduced amount of water. This will keep the roots from drying out too badly. It is important during hot weather to not water aloes too much, as this is a classic cause for rot, starting in their roots. Aloes respond well to fertilizers during the cooler months. Any available house plant food applied at ½ strength will show results.

The aloe flowering season in our region is late winter through early spring. The flowers are spectacular and are excellent hummingbird attractors. An aloe section of a desert garden adds diversity, beauty and interest to the landscape. The plants in previous paragraphs are tried and true here in Tucson. There are many others to experiment with and new ones should be available in coming years as seeds and plants make their way into the nurseries from the Arabian countries.

List of Growing Succulents in the Desert columns