Fortunate indeed are those whose climate allows them to grow succulents without the expense of heated glasshouses. This is possible, and widely practised, in southern Europe and the southern USA. in parts of South Africa and Australia, and in the north island of New Zealand. Frosts are not unknown in many of these areas, but are sufficiently slight toallowa wide choice of the more robust succulents to thrive unprotected.
Where the summers are hot and dry, as in California, many succulents are better suited than mesophytes for garden use. and are becoming increasingly popular as their peculiar attractiveness is more appreciated2. The sculptural effect of the noble, stiff leaves of agaves, the organ-pipe columns of cerei and the soft, fleshy foliage of the lowly ice-plants create a landscape that is unique and compelling. Great scope for artistic design lies in blending plants and garden ornaments with the architectural background.
Your own slice of desert. Succulents can be utilized in various ways. Sloping ground or raised beds provide the ideal site for a general collection, with the free use of rocks beneath which the roots can find anchorage and moisture (6.10). The soil should be porous but nutritious-sand alone has no food value—and a top dressing of grit or shingle is advisable to prevent the plant lying on wet soil. It also helps to keep down weeds, and provides a contrasting plain background to show off the special geometry of "desert" plants. Other xerophytes, not strictly succulent, such as Yucca, Nolina and Dasylirioti, fit in well with the display (6.8). Examples of landscaping with succulents can be seen on the grand scale at the Huntington Botanical Gardens in California, and in southern Europe (6.1, 8. 9, 10). For the choice of plants it is best to find a loca I supplier, because growth conditions vary in so many ways from one country to
On a smaller scale, succulents can be employed singly or in groups to fill corners too hot and dry for other plants and can be planted in decorative containers for terraces and patios. But despite their ability to withstand drought, they will benefit from watering if the summers are hot and rainless.
Ground cover and basket plants. Succulents offer a wide choice of ground-cover plants, which are especially welcome for clothing bare soil in places too parched for grass. A long list could be drawn up of shrubby Mesembryanthe-maceae: they come in a variety of leaf forms and flower colours, and many are showier than the original ice-plant, Mes-embryanthemum cryslallinum. White-leaved senecios such as S. serpens and S. kleiniiformis contrast effectively with the darker foliage of creeping sedums such as S. stahlii and S. spurium. Eche-verias, with their neat rosettes, are highly diverse in form and flowering.
Another use of succulents is in hanging baskets (6.16), where a lapse in watering may be fatal to mesophytes. For many kinds this is the ideal means of presentation, because it matches the way they grow in nature on cliffs and escarpments. A short list of the more obvious choices would include the rat's tail cactus (Aporo-cactus flagelliformis), Sedum morgani-anum and its hybrids, Ceropegia woodii and allied species, several crassulas (C. rupestris, for example), any of the 60 or so species of Rhipsalis. and Senecio rouileyanus.
Sunshades. For those wishing to specialize in succulents, the range of species can be extended by attention to their special needs. For instance, in much of California the fierce summer sun combined with drought upsets succulents
Right (6.10): Succulents bring a touch otthe exotic to gardens at Eze on the Mediterranean Coast where they relish the trost-tree climate high light intensity and sea breezes
Below (6.11): Cacti by the thousand in a commercial nursery in southern Calilornia. The yellow-spined plants are Echinocactus grusonii .the 'Golden Barrel'; on the left, tine specimens ot Agave victoria-reginae.
that are accustomed to different cycles of growth and dormancy. Partial shade is the answer for these, and it can be provided in two ways. The first makes use of a natural screen by planting suitable xerophytic shrubs and grouping the more delicate succulents beneath them. The second is the lath house, with slats but no glass, which not only breaks the full force of the sun in summer but also protects against an occasional frost in winter. In moist tropical countries such as India, protective structures are also needed to keep off the excessive rains.
Where the frost bites In countries where glasshouse culture is a necessity, collectors are intrigued by the possibility of growing succulents outdoors, unprotected, all the year round. The emphasis is on exotic and cactiform types here: the truly hardy sedums, sempervivums and Iewisias come more within the province of rock garden and alpine fans. Since the war years I have annually planted out surplus succulents to test them for hardiness, first in London and later in Reading (6.12-14). Especially prepared sloping beds are used, against a white south wall. The soil is extra porous, over coarse drainage material, and rocks are used as much as possible to isolate the succulents from wet surroundings. Fog and damp are a worse enemy than low temperatures (6.14). Where a plant is valued, a duplicate of it can be kept as a reserve under glass.
The novel effect of an "outdoor desert" is well worth trying, even if some replanting is needed after a severe winter. In the trials I have made with cacti, Opuntia robusta, O. rastrera, (6.12), O. poly-acantha and O. humifusa proved the most enduring. Globular cacti rarely last more than five years. Lobivia silvestrii (6.13) and Echinocereus viridiflorus being two of the best. Mexican agaves include a few that are hardy: Agave parryi, A. lophantha, and (with luck) A. americana. The danger is water collecting in the centre of the crown and causing rot. Of the Mesembryanthemaceae. I find Ruschia uncmata (6.12,11.9) by far the toughest: of the Aloineae, Aloe aristata
(13.9). Crassula sarcocaulis(6.12), in its red and white forms, is highly recommended. For ground cover, annual Portu-laca (5.3, 12.1) and Dorotheanthus
(11.10) may be sown. Along with these true succulents can be associated borderline succulents such as Yucca. Cordyline australis and some species of Dasylirion. as well as spiky Collelia, Eryngium, Acanthus and others that blend well with the general "desert" effect. My choice is necessarily personal: I can speak only for those I have tried. The door is wide open for experimentation, and different areas will nodoubt produce different selections of suitable plants.
As distinct from permanent plantings, many of the larger, tougher succulents may be put outdoors during the summer, either in pots or troughs, or plunged in a bedding display. The largest and spikiest plants are kept in pots for ease of handling; the smaller, unarmed species are bedded, lifted in the autumn when frosts are expected and then packed under the glasshouse staging with some earth covering the roots until they are ready for planting out again the following spring. "Hie main problem, apart from specimens growing too massive to carry, is the danger of introducing pests and weeds into the glasshouse when the outdoor plants are brought in for the winter. But such displays look after themselves during the summer, and their novel appearance excites much comment from passers-by.
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