Plants for Dry Places
Plants have found many methods for coping with heat and drought. Some, like theand other , have developed fleshy leaves, stems or ‘bodies’ which can store considerable quantities of water to last them until rain arrives to replenish these reserves.
Others cover their leaves with scales or hairs which insulate them from the heat and cut down the rate at which water evaporates from them. Yet others reduce the size of their leaves to tiny needles, which also reduces evaporation.
Some thrust strong roots deeply and almost vertically downwards in search of sub-moisture, and there are also bulbous- and tuberous-rooted plants which make all their growth in a limited season, when water is available, and then die down, relying on the moisture stored in their bulbs or tubers to keep them alive for many months.
These are the plants to look for when you want to fill a dry space in the garden. Most cacti are too tender to be grown out of doors in Britain, except temporarily in summer, but there are quite a lot of hardy succulents or semi-succulents including all the stonecrops (sedums) and houseleeks (sempervivums) In tribute to its hardiness, the common houseleek, tectorum, acquired its name because it will thrive on roofs with no more ‘soil’ than the dead leaves and other debris which may have collected in the corrugations of the tiles.
Others are echeverias, which somewhat resemble sempervivums in their succulent grey rosettes, but are less hardy and usually in need of protection in winter. The same is true of the agaves, large rosette-forming plants from Central America with fleshy, often spine-tipped leaves which in some varieties are conspicuously variegated with white or yellow. All the plants loosely known as are drought-resistant and so are gazanias and the succulent-leafed annual, portulacca.
The scaly, downy or hairy-leaved plants are usually silver or grey and this can be very useful from a decorative as well as from a utilitarian point of view. Grey borders, or borders in which greys and silvers predominate, perhaps with white, blue and pink flowers to complete a restful colour scheme, are much in fashion and almost all such plants prefer situations that are rather dry, certainly well drained in winter and summer.
The list includes a great many species and varieties of achillea, anaphalis, anthemis, artemisia,, cistus, convolvulus, dianthus, eucalyptus, helianthemum, helichrysum, hieraceum, hippophae, lavandula, lychnis, olearia, onopordon, perovskia, phlomis, santolina, senecio, stachys, teucrium, verbascum and zauschneria.
Brooms, genistas and gorse are familiar examples of shrubs with very small leaves, the green stems performing some of the functions normally associated with leaves. Incidentally, all belong to the great pea family, Leguminoseae, which is notably rich in plants that have adapted themselves to grow in dry places. Every lawn owner will be aware of the annoying way in which clovers and medicks, both members of the pea family, will survive long after grass is half dead through drought.
Many conifers use the device of small leaves to survive both dryness and intense cold and none is more adept at existing in extremely dry places than the juniper family with their tiny, awl-like leaves. Heathers, though also small-leaved, vary considerably in their tolerance of drought, some being accustomed to growing on very moist, acid moorland, but the taller kinds, such as Erica arborea, Erica mediterranea and Erica terminalis, will all survive a considerable degree of dryness. Tamarisks of all kinds survive dryness and are particularly good near the sea as they are also salt-tolerant.
Deep-rooted plants which grow well in dry soil include acanthus, anchusa, echinops, eryngium, hollyhocks, Papaver orientale and verbascums.
The best bulbous or tuberous-rooted plants for such places are those that make most of their growth in winter or spring, when the soil in Britain is rarely very dry, and then become partly or fully dormant in summer when it may well be dry. This group includes, and hyacinths and also a lot of smaller bulbs such as winter aconites (eranthis), crocuses, muscaris, scillas and chionodoxas. Nerine bowdenii and, where winters are mild, Amaryllis belladonna are other possibilities.
It is not so easy to find plants for places that are both dry and shady but there are a few that will survive even this awkward combination. They include ivies of all kinds,calycinum, foetidissima and Ruscus aculaetus.