Resilient plants in the garden of Carolyn Hughes in Sydney

The recent dire predictions of a hot, dry summer ahead, with the return of El Nino, are enough to make a gardener shudder. Scenes of heatwaves and wildfires in Europe and North America over the past few weeks are a harbinger of what could be in store for us this coming summer. The last three summers we have been lulled into a false sense of security, with mostly mild temperatures and lots of rain. We have to start thinking again about how to garden in times of heat and drought. Much depends on garden practices, but equally important are plant choices. Last week, I visited an inspiring garden where the owner, Carolyn Hughes, has been experimenting for ages with a very difficult hot, dry area in her garden, which provides lessons for us all.

The bed is at the top of a sunny slope at the front of the garden, and underneath it is a rock shelf, about 6 cm below the surface of the soil. Several enormous old trees are slap-bang in the middle of the bed - a golden Robinia and a huge gum tree - taking all the moisture out of the soil, and there are also a Jacaranda and a Chinese pistachio not far away on the nature strip that also have roots invading the bed! Carolyn has tried many different plants in the bed over the years, and she has come up with some really tough specimens that are not just surviving, they are thriving. As an added bonus, the bed looks great all year round!

Rhagodia parabolica Grey Edge in the garden of Carolyn Hughes in Sydney

Rhagodia parabolica Grey Edge in the garden of Carolyn Hughes in Sydney

Silver-foliage plants are ideal for this kind of garden situation, but not all are suitable for Sydney's humid summers. One of the standout successes in Carolyn's challenging bed is the silvery-leaved native saltbush called Rhagodia parabolica 'Grey Edge'. It forms a rounded shape about 1 to 1.5 m tall, and its unusual triangular, shimmering foliage is very pleasing, and echoes the hue of the bark of the gum tree and a Prunus persica (ornamental plum) in the bed. It seems incredibly resilient to the harsh conditions. I have also seen it growing well in sandy, coastal gardens in Sydney. There are several specimens of this shrub along the bed.

Dietes White Tiger, Alternanthera Little Ruby, Limonium perezii and lavender in the garden of Carolyn Hughes in Sydney

Dietes White Tiger, Alternanthera Little Ruby, Limonium perezii and lavender in the garden of Carolyn Hughes in Sydney

An excellent companion to the saltbushes is Dietes 'White Tiger', a sturdy, clump-forming perennial with cream-striped, grey-green, slim, strappy leaves. It is a relative to the annoying self-seeding Dietes grandiflora but though it still has the same white flowers as the species, it doesn't self-seed. The upright leaves provide a satisfying contrast of texture to the Rhagodia. A fine-leaved Lomandra, another tough customer, provides more linear texture, as does Pennisetum setaceum 'Rubrum' (purple fountain grass, ht 1-1.5 m), which has stunning burgundy foliage and tassels of fluffy flowers in summer that last well into winter. It provides an effective contrast to the silvery plants. Another plant with similarly coloured leaves is Alternanthera dentata 'Little Ruby', a compact perennial that does well in Sydney. In very cold suburbs, it can look ratty during winter, but it comes good after a prune at the end of winter.

Nandina domestica Nana

Nandina domestica Nana

Other shrubs that are doing well include a compact grey-green form of the native rosemary, Westringea (ht 50 cm); Ceratostigma willmottianum (Chinese plumbago, ht 1m), a wiry plant with gorgeous, brilliant blue flowers in late summer and autumn, and leaves that take on autumnal tints before falling in winter; Nandina domestica 'Nana' (ht 45 cm), which has brilliant coloured leaves in winter when grown in hot spot; spring-blooming Rhaphiolepis 'Snow Maiden' (ht 1 m); and a couple of robust Salvia x jamensis cultivars (ht 1 m).

Nemesia and Euphorbia Diamond Frost in the garden of Carolyn Hughes in Sydney

Nemesia and Euphorbia Diamond Frost in the garden of Carolyn Hughes in Sydney

Rugged perennials that cope with the harsh conditions include Euphorbia hypericifolia 'Diamond Frost' (ht 50 cm), which forms a rounded cushion and is spangled almost all year round with tiny, white flowers. The very old purple 'flag iris' (Iris germanica, ht 30 cm), which is often seen growing wild in abandoned country gardens, also does very well. This rhizomatous plant is one parent of the so-called 'tall bearded iris', with its many and varied coloured cultivars - but the original flag iris is probably the one that does best in Sydney gardens, starting to flower in winter and continuing on into spring. A tall Nemesia, which is a short-lived perennial, self-seeds from year to year providing a profusion of dainty, soft-pink flowers throughout winter and spring.

Trachelospermum jasminoides

Trachelospermum jasminoides

Some excellent resilient groundcovers form effective carpets between the trees and shrubs and one of the best is the variegated-leaf star jasmine (Trachelospermum jasminoides 'Tricolor'), with its green, white and pink leaves. Usually grown as a climber, it can be used equally well as a groundcover in either sun or shade, spreading quite wide once established. The plain green-leaved form can also be used in the same way. Other useful groundcovers that have done well for Cariolyn include Evolvulus pilosus (sometimes known as blue eyes); an old-fashioned, pink-flowered 'pigface' (Lampanthus); and a bright pink ivy-leaved Pelargonium that meanders around, highlighting the pink leaves of the star jasmine, and winds through the ornamental peach tree.

Salvia fruticosa Greek Skies

Salvia fruticosa Greek Skies

Even though much of summer is predicted to be hot and dry, we can still expect some storms with potentially heavy downpours, which means that heat- and drought-tolerant plants that cannot tolerate moisture will likely peg out after such rain events. This has happened in this garden area with various succulents and a magnificent planting of sailor boy daisies (Osteospermum) and Gazania a few years ago. Heat-resistant plants with a short shelf life are still included, but not mass-planted, so that their disappearance won't leave a big gap. Some plants are such good long-flowering doers for a few years, until they exhaust themselves, that Carolyn considers they are well worth replacing when they do expire. Examples of these include perennial statice (Limonium perezii, ht to 60 cm), with its long-flowering clusters of purple flowers on wiry stems; Salvia fruticosa 'Greek Skies' (ht 60 cm), with attractive grey foliage and beautiful blue flowers throughout spring; and lavenders.

To help the plants survive, Carolyn digs in hydrated coco-peat and compost when planting, applies a wetting agent to the soil a couple of times a year, and mulches the bed well to protect the plants from the intense heat of the sun in the warmer months. The garden bed is an inspiration for those facing similar challenges in the hot summer ahead! I'd love to hear of other plant suggestions for such tricky spots.