Aloes are excellent garden subjects and deserve a place in all South African gardens. Not only are the plants very attractive on their own, but the annual flowering season in winter brings bright and wonderful colour into the garden at a time when colour is usually absent in gardens. In addition the flowers attract a variety of birds like sunbirds and orioles to your garden. Because most aloes are capable to survive long periods of drought they are important elements in a water-wise garden.

They also do well in warmer areas in other parts of the world, some of the best aloe gardens are to be found in places like California and Portugal and other Mediterranean parts of Europe. Smaller aloes are popular in succulent collections all over the world.

Aloes occur naturally in most parts of Africa and Madagascar, extending their range into parts of the Arabian Peninsula. Only a few of the more than 130 South African (or the more than 600 species and varieties world-wide) are currently grown in gardens and collections in the country. There is an enormous scope for the extension of this short list by adding more South African species (and varieties) for those who would like a strictly indigenous garden and collection.  If your field of interest is not limited to political boundaries the numerous species from the rest of Africa, Madagascar and Arabia can be added.

There is a large variety as far as size, plant form, flowering time and flower colour is concerned. Some of the “exotic” aloes which have become available over the last few years obviously have a significant horticultural potential, many of them flowering in spring, summer and autumn. In addition aloe breeders have produced spectacular cultivars with special properties like masses of flowers and extended flowering times. There is no doubt that these cultivars have an enormous horticultural potential.

Aloes, like most other garden plants, do need good care, but the pleasure and satisfaction resulting from the effort is worth it all the way. In this article, caring for aloes is discussed from a South African view point; adaptations for local conditions must be made for other areas.

Planting and requirements

All aloes require a well-drained position. Most garden soils work well but it is essential that some form of organic material should be added, some well composted manure could even be beneficial, especially in the case of larger types of aloe. Adding bone meal when preparing the spot where the aloe is to be planted is definitely beneficial for future growth. Where the soil is clayish and water retaining, it is advisable to add some river sand or similar material into the mix. When transplanting, remove all dried roots, new roots will be formed after a few weeks. Be careful to introduce plants which have been in a shady position slowly to full sun, plants can get sunburn like people!

Aloes do need feeding from time to time, adding some liquid or granular fertiliser is beneficial for good growth and bigger flowers. Bone meal and fertiliser in small quantities are beneficial for the growing of healthy plants.

Some of the smaller aloes are grown more successfully in containers, the same rules apply for these, good drainage is essential.

Landscaping

Aloes combine very well with other indigenous plants and other succulents, the rockery should be well designed, get some advice from an expert or buy a good book on landscaping. Remember to take the eventual size of the aloe into account when planning your rockery. Also take into account when the species or cultivar you are planting will flower.

Aloes for cold gardens

Severe frost will kill many aloes; even a less severe cold snap in winter could destroy flowers. In cold areas plants could be grown in protected areas. Some aloes like Aloe polyphylla and Aloe reitzii come from very cold areas and can therefore be grown in very cold conditions, these two species flower in October and February respectively, avoiding cold periods altogether. Other aloes flowering when frost will not damage flowers include Aloe fosteri (flowering in March and April), the summer flowering form of Aloe cryptopoda (also flowering in March and April) and Aloe pretoriensis (flowering in April). A number of the aloes from the Arabian Peninsula have also proven to be quite frost resistant, flowering during the warmer months the flowers are to be enjoyed without concern of frost damage. Frost netting can be used to protect flowers, but the net should not lie directly on the flowers; this actually causes more damage to the flowers.

Aloe pests

Like most garden plants, aloes are susceptible to a number of pests, these occur naturally in the wild, but concentrating plants in the garden, often creates suitable conditions for the pests to spread easier than in the veld. All of these can be treated by the gardener who keeps his or her eyes open for signs of problems. Different species of aloe are usually susceptible to some pests and resistant to others. In the case of all the pests mentioned below the golden rule is not to allow the problem to get out of hand. A keen gardener will inspect his plants regularly to kill the problem in the bud. Controlling pests should of course always be done in such a way that the minimum damage is done to the environment. Not only would one try to avoid doing harm to animals like birds and bees, but it should be kept in mind that others like spiders, lady birds and lizards, are actually one’s friends in the battle. It is somewhat hard to admit that it is actually us who are creating the environment where species becomes pests, in pristine habitat there are no such things as pests, there nature keeps a balance between all species. 

Snout beetle

This is probably the most common pest affecting aloes in the garden. Two species of snout beetle attack aloes in the garden, a smaller one about 10mm long, and a much bigger one with a length of up to 25mm. Tell tale signs of the smaller beetle being present are round brown marks on the leaves, resembling the top of screw. When these are seen, it is important to take immediate action. Both beetles have a distinctive long snout, the smaller one will usually be found in the crown of the plant, the bigger one is much more difficult to spot as it hides underneath the aloe leaves where it eats away at the leaves and developing inflorescences. Both lay their eggs in the stem of the aloe and the larvae feeds on it, causing the plant to fall over and rot. The easiest way of treatment is to sprinkle a powdery pesticide (commercial product names change all the time) when the insect is seen or suspected. Spraying with an insecticide like Malasol or Marshall will also get rid of the beetles, unfortunately these treatments might not reach beetles hiding underneath the leaves or larvae already present in the stem. A systemic pesticide like Dimethioate could be more suitable. For those who prefer not using pesticides the only solution would be to physically remove and kill the insects as soon as they are spotted, this is really a viable option for the keen gardener.

Scale

A white scale often appears on aloe leaves, the insect involved is enveloped in a hard skin which protects it against predators (and treatment!) while it is sucking sap from the plant. Not only does this make the plant unattractive, but over a long period the plant can be killed slowly. A pesticide like Malasol may be used; a mineral oil like Oleum must be added. The oil in fact smothers the insect, when the problem is spotted early the scale can even be treated by painting it with used cooking oil. Another environmentally friendly method which works well is wiping the infected leaves with a cloth soaked with dishwashing liquid, after an hour or so it should be possible to wash away the insects with a strong squirt from a hose pipe. The treatment should be repeated until all signs of the scale disappear.

Aphids and woolly aphids

Some aloes are very prone to aphids and woolly aphids; these are usually found in the crown and soft growing point or in between the leaf bases, very often carried onto the plant by ants which feed on an excretion of the aphids. These can also be treated by dusting one of the powder pesticides or by spraying with a registered aphicide. Some growers have had success treating the plants with a weak soapy solution.

Aloe cancer

Cancerous growth on aloes can be a very serious problem, not only is it unsightly, but in the case of soft-leaved species it can kill the plant if left untreated. The growth is caused by a minute white mite which induces the abnormal tissue to create a suitable habitat for itself. All of the abnormal growth must be removed with a sharp knife. The wounds can be treated with a strong solution of Dimethoate. A treatment which have been used with success lately, is painting the abnormal growth with neat Formalin, make sure that only the abnormal growth is treated, the Formalin will kill both the mites and the treated plant material, stopping the abnormal growth. Seedlings and young plants cannot be treated this way. Formalin which can be bought at most pharmacists, must, of course be handled with care. Plants can also be sprayed with a systemic pesticide registered for mites like Biomectin or one of the pesticides which is also effective for the treatment of mites (listed below). It should be noted that that is known that regular use of pesticides could actually increase mite attacks due to the removal of natural predators of the mites. Some of the pesticides formulated for insects have no effect on mites, which are of course not insects, but relatives of spiders. Please remember that spiders are never to be considered a pest, they actually predates on many garden and home pests. 

Leaf bugs

Sometimes small insects are spotted, moving very quickly on the surface of the leaves. If left without treatment the leaf starts showing the effects of the insects sucking on it, small white spots give it an unhealthy appearance. The problem can be treated by spraying with a pesticide like Malasol. A soapy solution will be a non-toxic solution.

Sucking insects

A problem which occurs only in summer (pests are, of course, more active during the warmer months) is that the flower buds suddenly aborts and fall off. This is probably caused by an insect sucking the sap in the developing bud. A treatment which we have found very effective for this problem is spraying the developing inflorescence with the systemic pesticide Dimethoate.

Rust

The most important form of rust attacking aloes is a fungus causing fairly large yellow spots on the leaves, which grow larger over time and eventually release masses of spores. Once again, some species of aloe are much more susceptible to this disease than others. It occurs most frequently on plants which do not get enough sunshine and is most prevalent in wet weather conditions. Infected leaves should be removed and if possible a more sunny position should be considered. A fungicide like Benlate could be alternated with Dithane or Virikop as treatment. Formalin has been used with success for this problem as well; the infected part should be painted with neat Formalin.  Black spots on aloe leaves caused by another fungus are unsightly and should also be treated with a fungicide.

Ants

Ants have already been mentioned in association with aphids above. Often when a plant looking unhealthy is dug out; it will be found that the roots are hanging in the air because of ant activity. A rule would be to keep aloes free of ant infestation. Pesticides registered for ant control works well in this case.

Short list of chemicals which may be used on aloes 
 

Insecticides:
Dursban (active ingredient: Chlorpyrifos)
Marshall (active ingredient: Carbosulfan)
Malasol (active ingredient:

The following insecticides are effective for mites as well:
Dimethoate (active ingredient: Dimethoate)
Parsec (active ingredient: Amitraz)
Seizer (active ingredient: Bifenthrin)

Mitecides:
Biomectin (active ingredient Abamectin)

Fungicides:
Benlate (active ingredient: Benomyl)
Octave (active ingredient: Midazole)
Bravo (active ingredient: Chlorothalonil)
Bumper (active ingredient: Propiconazole)
Dithane (active ingredient: Mancozeb)
Virikop (active ingredient: Copper oxychloride)

Remember that it is always advisable to add a wetter/sticker when spraying.

Caring for some special aloes

Aloe polyphylla or Spiral Aloe is best planted on a sloped position in a rock garden with a very well drained medium that is rich in organic matter. The plants require ample watering and should preferably not be left to dry out completely during the growing season in summer, it does in fact needs to be fairly regularly watered in winter as well. When the plants are transplanted one should take care not to damage or disturb the roots too much, prevention should also be taken to keep the roots moist when exposed. Plants should get ample sunshine, at least a full morning’s sun, plants that are grown in shady positions are very susceptible to aloe cancer and to rust which can be fatal to the plant which has very soft leaf tissue (unlike most aloes with harder leaves). It is very important to keep the roots cool, this can be done by covering the soil around the plants with mulch like bark chips or by putting flat rocks next to the plants, both of these also help with moisture retention. Coming from the highlands of Lesotho, the aloe can survive extreme cold weather; it flowers in late spring, when all danger of frost is past.
This aloe is an excellent feature plant in a fairly large container next to the pool or on the patio. It must be remembered that it would like an open spot with lots of sunshine and lots of air movement and that the container should be well drained as well. Unglazed clay pots are very suitable, they give better drainage and because of evaporation keeps the growing medium nice and cool.

Aloe barberae or Tree Aloe can be grown very successfully in warmer gardens. It forms a very nice tree with attractive orange to red flowers in winter. It grows fast if planted in fertile soil and given ample water, especially in summer. It is susceptible to scale, and this should be treated before spreading to large parts of the tree.

Aloe plicatilis or Fan Aloe comes from a winter rainfall area; it should therefore be watered fairly well in winter, a bit less in summer. It prefers sunny spots as well. It is very attractive if planted in a suitable container or if planted in the rockery.

Aloe dichotoma or Quiver Tree or Kokerboom is not the easiest aloe to grow; it comes from very dry areas. It should be planted in a very well-drained spot or container. It is very prone to aphids in its crown and should be treated for this regularly. Large plants which are replanted do not root easily; plant may look healthy for up to two years without forming any roots, before starting to rot from the bottom of the stem. It is very important to keep the plant growing actively, bone meal in the soil will help, if the soil is well drained, it could handle quite a bit of water. Regular treatment with a fungicide like Benlate will help to keep the plant healthy.

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