Is your garden looking tired and dusty? This month, Flo Whitaker recommends plants that revel in summer heat and will keep on looking good until autumn
If you’re bewilderedly wandering around the garden centre, searching for plants that won’t shrivel in the heat, seek out those with light-reflective grey or silvery foliage as this usually indicates drought tolerance. Likewise, plants with tiny leaves, succulent or hairy foliage, are often better equipped for hot conditions. Small leaves have reduced surface areas – so less moisture loss. Succulent leaves mimic water reservoirs, while hairy foliage insulates from temperature extremes and also traps precious dew and moisture (a clever adaptation from desert environments).
Convolvulus cneorum is the perfect rockery plant; a compact, shrubby perennial with drought-busting silvery foliage and white funnel-shaped flowers. Convolvulus mauritanicus has periwinkle blue trumpet flowers and small grey/green leaves that casually tumble over walls or pot edges. It takes root wherever the stems touch the soil and, providing the soil is well-drained, is fully hardy.
Silver-leaved plants are ideal for seaside-themed or gravel gardens, as are many herbs, including rosemary, lavender, thyme and sage. Verbascum, artemisia, senecio, eryngium and shrubby nepeta, (Catmint) also enjoy full sun and free-draining soil. Verbenas are practically indestructible in heat. They are a large, diverse family; from low-growing bedding plants to stately verbena bonariensis that’ll attain 2 metres.
If it’s height you’re after, annual forms of ipomoea will revel in sunshine and speedily reach 3 metres. Don’t panic – although related to ‘Bindweed’, these non-hardy characters won’t set seed and rampage over your garden!
The Passiflora family, (Passion Flower) are vigorous perennials with astonishing blooms. Some forms won’t survive outdoors in the UK and are more suited to conservatory life. Curb their thuggish tendencies by regularly removing excess growth and carefully choose the planting site as you’ll need ‘room to prune’. Campsis, (Trumpet Vine) is another borderline-hardy climber, but will usually cope outdoors in southern regions, especially if grown against a sunny wall. The more heat and light you can give campsis, the more it’ll flower. Like passiflora, it needs to be kept firmly under control.
The fleshy leaves and roots of agapanthus are adept at holding onto moisture and their bold seed heads give them a long season of interest. Don’t believe the myth about keeping agapanthus starved and cramped in small pots – yes, they’ll survive grim conditions, but will positively thrive when given space and nutritious compost.
For summer patio pots, try sun-loving foliage plants such as variegated trailing nepeta, dichondra ‘Silver Falls’ or furry-leaved helichrysum petiolare – and don’t forget those old stalwarts; potted geraniums. Most varieties of bedding geraniums and pelargoniums are derived from indigenous South African forms. Heat and drought seldom trouble them, making them ideal candidates for hot conservatories. In fact, overwatering is what usually kills them off, so when an absent-minded friend forgets to do the watering while you’re away, your pelargoniums will be perfectly content.