Mediterranean Garden Society
Mediterranean Garden Society
Growing Aloes in our Succulent Garden
by Andrew Sloan reprinted from The Mediterranean Garden No. 86 October 2016
The photograph at the top of this page shows Aloe bellatula (Photo Wiki Commons)
Andrew’s photographs of many of the aloes in his collection can be found in the Gallery of Aloes
Andrew writes: In a previous issue of this journal (TMG 69, July 2012) I wrote about how we were changing to a waterwise garden, inspired by an MGS trip to Israel. In the present article I’d like to focus on aloes and on how we grow them in our succulent garden.
Almost everyone, I think, will know Aloe vera, now widely naturalised and grown as a medicinal plant, and most people will also be familiar with the commonly grown Aloe arborescens, but many other aloes are little known. There are in fact more than 500 Aloe species distributed across sub-Saharan Africa, Madagascar and the Arabian peninsula, of which I have so far managed to collect 120. Conveniently for me, just as I started to become interested in aloes a wonderful book entitled Aloes, The Definitive Guide was published by the Royal Botanical Gardens, Kew with photos and detailed information about each species. It is a big book of 700 pages and not cheap but quite indispensable to the aloe collector and frequently referred to as the Aloe Bible.
This book separates aloes into the following groups:
A. Grass aloes. These are plants with long narrow leaves, often grass-like, and a simple inflorescence. I have only one (A. cooperi), too small to have flowered yet.
B. Maculate aloes. These are sometimes referred to as spotted aloes and are quite difficult to identify without the inflorescence because of the similarity of their leaves. All the species are stemless and most sucker out to form large clumps, with the tips of the leaves frequently curling up when stressed. Aloe maculata, formerly called A. saponaria (soap aloe), is the most commonly grown in my area of Southern Spain but my personal favourite is Aloe fosteri which bears brightly-coloured yellow or orange flowers branching out up to a metre in height in the autumn.
C-F. Stemless aloes, separated into small/large clumps with few or multi-branched flower stems. Aloe vera belongs to this group along with a number of very showy aloes with spectacular flowers. Aloe buhrii, A. capitata and A. suprafoliata are among my personal favourites for this reason and I also like the reddish stressed colour of the leaves when plants like A. dorotheae are exposed to full sun in the summer.
G. Pendulous or sprawling aloes. In their natural habitat they are often found growing on cliff edges or among rocks in countries such as Ethiopia and Yemen and they branch out to form a large, sprawling group. Aloe pendens and A. jacksonii are both growing well in my garden in small groups.
H. Shrubby aloes, flower stems few and branched. Aloe kedongensis from Kenya has large red flowers which last for several months and is one of my favourites, as is A. andongensis with attractive light green leaves and orange flowers. Both branch freely from the base so are easy to propagate.
I. Shrubby aloes, flower stems multi-branched. Like the previous group a lot of these aloes come from East Africa and have attractive leaves, branch formation and inflorescences. Aloe nyeriensis, A. elgonica and A. camperi are personal favourites and are growing well for me and I am excited about growing the spectacular A. pseudorubroviolacea from Saudi Arabia.
J. Tree aloes. Tall aloes whose wide green and grey-blue leaves of different shapes, reddish-brown teeth and multi-branched colourful inflorescences make them some of the most exciting aloe species. Aloe arborescens is the most common while A. thraskii, A. ferox, A. marlothii, A. rupestris, A. africana and A. dichotoma from South Africa are some of the most striking. There are also some special aloes from Madagascar like A. helenae, A. vaombe and A. vaotsanda, though these are less commonly grown.
Hybrid aloes
Most aloes are not self-pollinators, i.e. a plant will not set seed with its own pollen, therefore two plants of the same species are needed to produce true seeds of that particular plant. Aloes grown from seeds arising from uncontrolled pollination in a garden are therefore likely to be hybrids. There are a number of natural hybrids which occur in the wild where different aloe species share a locality and flower at the same time, such as A. arborescens × ferox which is spectacular. In South Africa, Sunbird Aloes & De Wet Plant breeders are growing some very attractive hybrids although these plants are not available in Europe. These growers transfer the pollen from one species to a receptive stigma of another species and after the seeds have germinated in a controlled environment a selection process starts whereby weak and inferior plantlets are eliminated so that the final product is a vigorous, fast-growing and attractive plant. A very good book highlighting 60 of these hybrids has recently been published, Garden Aloes, Growing and Breeding Cultivars and Hybrids by Gideon Smith and Estrela Figueiredo. These same hybrids are available in Australia under the name aloe-aloe. The photographs of these plants that I have seen are impressive. Some smaller hybrids originating in California are now available in Europe, at least at my local garden centre in Spain, and do particularly well in pots.
Our succulent garden
We live in southern Spain 40 km west of Malaga in the countryside at an altitude of 300 metres, with hot dry summers with temperatures in the high 30s and with an average of 530 mm of rain from October to April (although not during the last two winters as we are currently in a drought phase). We do not normally get frost in the winter; I estimate that we are in the equivalent to USA Plant Hardiness Zone 10a.
Outside our kitchen we have a south-facing terrace that looks out on to our main garden area with two retaining dry-stone walls each about 1.5 metres high and stretching out for about 60 metres. The stone walls are four metres apart, the first at ground level and the one behind at the garden level so the plants are basically at eye height which makes for good close-up appreciation.
When we decided to change our garden five years ago to a waterwise one we had to take out the old plants and improve the drainage by mixing several lorry-loads of river sand into our clay soil, which we had improved in previous years with goat manure and compost. Good drainage is essential for growing aloes and other succulents. Two attractive bushes survived from the previous garden, a heliotrope and a large Russelia equisetiformis; both are at the front and help to break up the garden into different areas.
The most important area for us is just off the kitchen terrace, which is our outside living area and adorned with a variety of succulents in pots and several hanging baskets of Lepismium cruciforme (syn. Rhipsalis cruciformis) and Sedum morganianum. We decided to plant two Caesalpinia gilliesii about 20 metres apart to provide some shade and long-lasting summer flowers, and in the middle put in a large Aloe marlothii hybrid, which produces bicoloured yellow and orange flowers in late spring. This is the focal point of this part of the garden and around it we have put smaller plants like the aloes Aloe greenii, A. claviflora, A. pendens and A. jacksonii, the agaves Agave xylonacantha and A. potatorum and some crassulas, notably Crassula pubescens subsp. radicans and C. capitella ‘Campfire’, as well as small cacti. In front of the large aloe we have put a Sedum nussbaumerianum, its copper tone contrasting nicely against the red of the crassulas, and a S. rubrotinctum. In between we have some small aloes – Aloe peckii, A. ‘Cosmo‘, A. humilis, A. aristata and A. distans – around which we have put small and medium-sized stones which are both attractive and provide shade for the roots in the summer heat, an inorganic mulch which succulents prefer. In the back row we have planted some large aloes such as A. rupestris, A. helenae, A. kedongensis, A. nyeriensis and A. vaombe, all of which will grow to two or three metres tall, mixed up with some large aeoniums and cacti, most notably Echinopsis spachiana (syn. Trichocereus spachianus) with its huge creamy-white flowers. The colours of the aloe inflorescences and their blue and green leaf colours are nicely highlighted against the background of the light grey stone wall while the sun lights up the frequently reddish colour of the teeth on the leaves, especially in winter when the sun is lower. Big stones have been put around the bases of the large aloes to provide shade for the roots and in some cases to support the trunk.
In other parts of this garden we have followed the same structure: large at the back, medium in the middle and small at the front. In one section I have a number of small aloes from Somalia and Ethiopia with spotted green leaves (A. somaliensis, A. mcloughlinii) and behind them I have put a selection of Madagascan aloes with capitate flower racemes, which should be spectacular if they prosper. I am still on a learning curve and plants can be quite particular about whether they like it in our garden or not, sometimes growing well in one part of the garden and failing in another area with a slightly different microclimate so I am still continuing to grow other aloe varieties as a back-up replacement for plants that fail. Aloes don’t seem to mind being moved and many a time I have replanted and changed a position after seeing it planted out in the garden or if it has become too big. As I garden according to the lunar calendar I try to do this during the waning or descending moon phase on a flowers day (see my article on this in TMG 61, July 2010).
There are several other parts of the garden where we have also planted aloes and other succulents without providing better drainage for the whole area. There we have made good-sized holes and mixed in river sand and some compost with the clay soil before planting. Outside the front door in a small area a large Aloe thraskii is the centre point and around it are planted smaller aloes, agaves and crassulas, and at the front some red-leaved Aloe dorotheae has spread out in a small clump around which blue Senecio talinoides has been planted. Even without flowers the different colours of the leaves and the contrast in structure of the succulents make for a very colourful garden all year round.
The original intention was not to water at all in the summer when we have no rain for four or five months. Most of the plants would survive this regime but would not really thrive so we are now following sensible advice from more experienced succulent growers and watering once every three weeks from June to September. I do this by hand with a hose early in the morning, trying to water at the base of the plants and not to leave water on the leaves or the crown of the plant which they don’t like. The leaves of the aloes tend to close up and in some cases the tips of the leaves curl up or burn, but the arrival of the first rain in late September or October brings an instant relief and they open up again. The plants are particularly vulnerable in the first year before their roots are well established and I try to plant in the autumn to establish them before winter. We very rarely get frosts in the winter but if global warming brings us some extremely cold weather in future winters then most of the aloes would need some protection such as a sheet wrapped around them, as growers do in California when they have a frost.
I have found it very satisfying to grow aloes from seed, although some patience is needed as it can take a number of years from germination to flowering. It is a good way of growing the larger tree aloes and other uncommon plants not to be found in nursery gardens. I sterilise my mix of cactus potting soil and river sand, let it cool and put it in some seedling pots, scatter the aloe seeds on top and cover them with some more sterilised river sand. I soak the pots in a tray to water from beneath and after draining off the excess water put them inside a clear plastic bag which I close and place in a light, but not sunny, spot with a temperature of at least 20 degrees Celsius. Healthy seeds should germinate fairly quickly and should continue to be watered from beneath in a tray for the first few months so as not to disturb the roots. Silverhillseeds and koehres-kactus.de are two reliable seed suppliers.
Cuttings or off-shoots from aloe species that branch or sucker will root easily provided that the cut surfaces are allowed to dry in order to allow callus formation. I like to try and dig out the offshoots by loosening the soil around them and gently pulling them out with any roots they have. Larger, spinier aloes can be difficult to handle or weed around and I have found that a pair of Fox Gloves stretching up my forearm provides good protection, whilst retaining flexibility in the fingers. I was very lucky to find two other gardeners growing aloes nearby and they have been very kind in giving me cuttings and off-shoots from their plants. These have included some quite rare plants like Aloe peckii from Somalia and as this species suckers out quite freely I have been swapping this and other plants with friends I have made on Planet Aloe in Facebook. Aloes will last for several weeks without water and can easily be packaged up in newspaper and tissues, having first shaken the soil off the roots, and posted to a friend elsewhere in Europe in an old shoe box. Nursery gardens are starting to have more succulent plants available including some small aloes, otherwise there are specialist on-line nurseries like Joel Lode at cactus-aventures.com, cb-succulentes.com (for Madagascar aloes) or pepiniereissa@hotmail.com, from all of whom I have bought good quality aloes.
I hope this article will transmit the pleasure and satisfaction there is to be had from a succulent garden. I shall finish as I did my last article by saying that collecting aloes seems to be addictive – but I think it is a healthy addiction!
THE MEDITERRANEAN GARDEN is the registered trademark of The Mediterranean Garden Society in the European Union, Australia, and the United States of America