If seeing your lawn turn straw-like every time the temperature rises and rainfall drops off worries you, you may be happier replacing it with gravel or paving. Paving a sunny spot will make the area even hotter, and this will have an effect on the plants you choose in the vicinity. If you cannot live without a lawn, a very high-grade mix will usually recover better after drought than an all-purpose one. If you intend to lawn a large area where water shortage could be a problem, some seed companies will supply you with a special drought-resistant mix not available ‘over the counter’.
Raise the mower blades during a prolonged dry spell, and leave the clippings on to prevent excess moisture loss. Do not fertilize or apply weedkillers, especially in dry form, if a period without rain is forecast.
A humus-rich soil will retain moisture much longer than one containing no organic matter. Keep your soil in good heart by incorporating manure, compost, or any of the other bulky soil additives.
A 154-2 in. (40-50 mm) mulch of bulky organic material, such as chipped or pulverized bark, farmyard manure, well rotted garden compost, shredded garden refuse or cocoa-shell or, alternatively, a covering of pea gravel, black polythene or porous mulching sheet will help to retain moisture in the soil. Polythene and other mulching sheets can be disguised by covering with a thin layer of soil or gravel.
Moisture-loving plants are nearly always likely to need additional watering in dry spells. With the aid of soil conditioners and mulches, it is possible to grow a reasonably wide range of popular plants, but unless you have a naturally wet area fed by springs, you may have to forget about water gardens and bogs requiring regular ‘topping up’.
Plants with grey foliage are generally very drought-tolerant. The grey colour is due to millions of tiny hairs over the leaf surface which cut down transpiration, thus preventing undue moisture loss. Plants with succulent or semi-succulent leaves, such as ivy-leaved pelargoniums, mesembryanthemums and portulaca, will also survive long spells without water successfully, as they store large quantities within their tissue. However, these drought-adapted plants, most of which have originated in warmer climates than our own, are ill-equipped to deal with severe wet and cold. Hairy-leaved plants will often rot during a long wet period, and if the wet leaves are frosted as well, severe damage occurs. Succulent plants can also rot in excessively wet conditions, and will usually die in frost as the stored moisture in the leaves can freeze and burst the leaf cells. Such plants should be used with caution in most parts of Britain, or treated as half hardy and given cool glasshouse protection in winter.
Many alpines, especially those with succulent cold-tolerant leaves, like sempervivums, sedums and some saxifrages, are naturally geared up to tolerate conditions receiving very litde water. Some rockery plants sold as ‘alpines’ are, however, merely dwarf forms of shrubs or herbaceous plants requiring normal quantities of water in order to survive. If you wish to grow the widest range of these plants, you may find it better not to construct a raised rock garden as such, but instead create a modified ‘scree’ level with the ground and mulched with granite chippings or pea gravel. This will dry out less quickly, while providing a cooler root run.