Which plants cope with drought in a UK garden?

Lists of drought-tolerant plants are easy to find and are not much use on their own, because they tell you what to buy without telling you what to look for or why half of them die the following spring. The useful skills are reading the adaptations off a plant in front of you, and understanding why wet winter soil kills more Mediterranean plants in Britain than any drought does.

Step by step

1. Learn to read the leaves.Silver and grey foliage reflects light and reduces leaf temperature. Hairy or felted leaves trap a layer of still air that slows water loss. Waxy or glossy surfaces reduce evaporation. Small, narrow or needle-like leaves have less surface area to lose water from. Aromatic oils in the leaves, as in lavender, rosemary and thyme, also reduce loss. A plant with two or three of these is telling you where it evolved.
2. Learn to read the roots and the structure.Fleshy or succulent leaves and stems store water. Deep taproots reach moisture far below where a lawn or bedding plant can. Bulbs, corms and tubers avoid drought entirely by going dormant underground through the dry season, which is why so many Mediterranean bulbs are effortless here.
3. Understand the British complication.Most drought-tolerant plants come from climates with hot dry summers and cool dry winters. Britain provides the cool but not the dry. What kills lavender, rosemary, cistus and most silver-leaved plants here is not cold — it is roots sitting in cold wet soil all winter. This single fact explains most disappointment with drought planting.
4. Fix drainage before choosing plants.On heavy clay, incorporate grit, plant on a slight mound so the crown sits proud, and mulch with gravel rather than bark so the collar stays dry. A raised bed or a gravel garden is the reliable way to grow Mediterranean plants on clay. Getting this right matters more than which cultivar you buy.
5. Consider natives and long-established garden plants too.Drought tolerance is not only about Mediterranean species. Many plants that thrive on thin chalk or sandy soils here — sea holly, verbascum, achillea, catmint, hardy geraniums, euphorbias, many ornamental grasses — cope with drought and with a British winter, which is a considerably easier combination.
6. Match the plant to the actual spot.A drought-tolerant plant is not one that never needs water. It is one adapted to a hot dry position, and it will sulk in damp shade just as a moisture-lover fails in dry sun. Map where the sun and the dry spots actually are rather than assuming.
7. Water new plants properly regardless.Every plant, drought-tolerant or not, needs watering through its first growing season while its roots are still confined to the rootball it arrived in. Drought tolerance is a property of an established plant. Trees and shrubs need this care for at least their first full year.
8. Plant in autumn wherever you can.Autumn planting gives roots the whole cool damp winter and spring to establish before facing their first summer. It is the single biggest improvement most people can make to survival rates, and it costs nothing.
9. Do not feed or over-improve the soil.Rich soil and generous feeding produce soft, sappy growth that is both more drought-sensitive and less winter-hardy. Mediterranean plants in particular want lean, sharply drained soil, and grow better and live longer with less.
10. Mulch with gravel rather than bark.For drought planting, a gravel or grit mulch keeps the soil surface cool and reduces evaporation, while keeping the crown of the plant dry — which matters far more here than the extra nutrition a bark or compost mulch provides.

Tips

• Ornamental grasses are among the most reliably drought-tolerant garden plants in Britain and give structure through autumn and winter as well.
• The Royal Horticultural Society and most good nurseries flag drought tolerance in their plant descriptions. Combined with reading the leaves yourself, that is enough to choose confidently.
• Planting densely so foliage shades the soil reduces evaporation considerably. Bare soil between plants is where the water goes.
• A plant grown hard, without feeding and without frequent watering, develops a deeper root system and is far tougher than the same plant grown soft.
• Do not confuse drought tolerance with neglect tolerance. A gravel garden still needs weeding, and weeds compete for exactly the water you are trying to conserve.

Common mistakes

• Assuming drought-tolerant means no watering when newly planted — Every new plant has roots confined to its original rootball for a season or more. Drought tolerance only applies once established, and the first year is when most losses happen.
• Planting Mediterranean species into unimproved heavy clay — They are killed here by wet roots in winter far more often than by cold or drought. Drainage, a raised planting position and a gravel mulch are what make them survive.
• Feeding drought planting generously — It produces soft growth that wilts faster and is less hardy. Lean soil produces tougher, longer-lived plants.
• Bark mulching around lavender and similar plants — It holds moisture against the crown through a wet winter, which is exactly the condition that rots them. Use gravel or grit for these.

Questions people ask