Why Sandy Soil Dries Out So Quickly

Sandy soil is made up of relatively large particles with plenty of air space between them. Water runs straight through rather than being held around the roots, and nutrients wash away with it. The upside is that sandy ground warms up early in spring, drains freely in winter and rarely waterlogs — which is why so many Mediterranean plants settle into it so happily. The downside is that a dry spell in July can leave shallow-rooted plants struggling within days.

If a cane pushes into your soil easily and a handful crumbles rather than clumps, you are almost certainly gardening on sand. Rather than fighting it, the sensible approach is to work with it: choose plants that evolved on dry, gritty hillsides, and give them a little help while they establish.

Improving the Ground Without Fighting It

You will never turn sand into loam, and you do not need to. The goal is simply to increase its ability to hold water and nutrients, and the easiest way to do that is with organic matter.

• Spread a 5–7cm layer of garden compost or well-rotted manure over the surface each autumn and let the worms work it in.
• Mulch every spring with bark chip, leafmould or gravel. A mulch slows evaporation and keeps soil temperature steadier.
• Dig in organic matter only where you are actually planting. Deep, repeated digging dries sand out further and destroys the fungal threads that help plants find water.
• Resist heavy feeding. Flushy, high-nitrogen fertiliser pushes soft growth that wilts at the first sign of drought.

Building up sandy soil is a long game. Do it every year and you will notice the difference in how long a border stays damp after rain.

Three Plants You Can Rely On

If you want certainty in a sunny, sandy border, start with these three.

Lavender. English lavender, Lavandula angustifolia, is the toughest type for British gardens — 'Hidcote' and 'Munstead' are compact, fragrant and reliably hardy. It needs full sun, sharp drainage and a light trim straight after flowering in late August. Never cut back into the old, leafless wood, because it rarely regrows from there.

Rosemary. An evergreen shrub that shrugs off drought once established and gives you year-round structure as well as cooking herbs. 'Miss Jessopp's Upright' makes a neat vertical accent. It is happiest against a warm wall in colder parts of the country, and it dislikes sitting in wet soil in winter far more than it dislikes a dry summer.

Sedum. The border sedums, now properly called Hylotelephium, are superb on sand. 'Herbstfreude', often sold as 'Autumn Joy', carries flat heads of pink flowers that turn bronze and feed late bees. Leave the faded stems standing through winter for frost to catch, then cut them back in early spring.

More Plants for Dry, Sunny Ground

Once the framework is in place, fill the gaps with these tried-and-tested performers. All of them cope with sandy soil and full sun.

• Shrubs: cistus, santolina, perovskia and the grey-leaved phlomis.
• Perennials: nepeta, salvia, achillea, eryngium, kniphofia, verbena bonariensis and stachys.
• Low carpets: thyme, helianthemum and drought-tolerant ornamental grasses such as blue fescue.
• Bulbs: alliums, tulips and nerines, which are made for ground that bakes in summer.

Grey and silver foliage is a useful clue here. Plants with hairy, waxy or narrow leaves have usually evolved to cope with heat and drought, and they look good together in a gravel garden or a south-facing border.

Planting and the First Season

New plants need help for one season only; after that, most of the plants above look after themselves.

• Plant in early autumn or spring, when the soil is moist and temperatures are mild.
• Water thoroughly at planting and keep watering through the first summer — a good soak twice a week beats a light sprinkle every day.
• Water the root zone rather than the foliage, aiming for around five litres per shrub each time.
• Mulch after planting, keeping the material clear of stems and crowns.
• Space plants slightly closer than usual if you want quick cover, then thin them as they fill out.

Care Through the Year

Keep on top of a few simple jobs and a sandy border will improve year on year. Trim lavender and rosemary lightly in late summer, but leave any hard pruning until growth restarts in spring. Cut back spent perennials in early spring rather than autumn, so seed heads and hollow stems can shelter wildlife over winter. Top up the mulch each spring, and divide crowded sedums every three or four years to keep them vigorous. If a plant sulks after a wet winter, it is almost always drainage rather than cold that has done the damage — lift it, work a handful of grit into the planting hole, and replant.