When in drought . . . planting for a parched summer

Bigger picture or local ups and downs: to which should we look in order to plan for the best? Investors live with this question but so do gardeners, whose dilemmas are often similar. For gardeners the bigger picture is the warming climate. The local question is how it will affect that important little space, their own garden. 

In the past 17 weeks, the climate has been vilely cruel to mine. In much of Europe it has been even worse, but in and near Oxford minimal rain has fallen in my gardens since March 7, the driest spring-to-midsummer they have ever endured. I wrote here that ideal conditions had at last returned at ground level on June 7. Perhaps the text provoked that cruel abuser, Mother Nature. No worthwhile rain then fell for the rest of the month.

The hasty conclusion might seem to be that the garden must change totally. Here is an easy perennial recipe for success in dry summers. If you have space, plant a big drift of pale blue-flowered perovskia, a loosely shaped grey sub-shrub from Afghanistan. Its woody stems are 3ft to 4ft high and die back in winter, but in dry summers they flower on and on. 

Perovskia flowers on and on during dry summers © GAP Photos/Julie Dansereau – Design: Piet Oudolf
Bright yellow flowers of Santolina chamaecyparissus contrast well with perovskia © GAP Photos/Richard Bloom

In front of the perovskia, plant lots of cotton lavender, about 2ft high. The easiest and brightest is the silvery leafed Santolina chamaecyparissus, which has flowers like buttons in a strong shade of yellow. I leave these flowers on the plant as they contrast well with pale perovskia, but others find them too bright and cut them off. The stems of a cotton lavender need pruning back hard in late March to stop the plants becoming bare and straggly in their middle. If you have room for a long line of perovskia you might mix in a few individual plants of the best tall grass, Stipa gigantea, using it at intervals of several yards and leaving its stems to arch up to 5ft as a contrast at a greater height.

This combination is easy, drought-proof and willing to grow in any sunny soil, the poorer the better. Another foolproof one majors on lavender galore, the dark blue Hidcote variety to the fore, with intermittent bushes of the small-flowered pink rose Cécile Brunner, pruned to neat dimensions, to break up the blue continuity. And yet there is still more to summer than these mainstays. Even in this dry year there is also more to Britain than universal drought.

Some of you have kindly emailed me during the south’s dry months with pictures of green fields in Northern Ireland or green slopes in Derbyshire to remind me that not every garden has been desiccated. Within the general pattern of warming and drying there are usually exceptions, one of which may be your garden, another, a year like 2024. Afghan sage and cotton lavender are not the only future always, everywhere. 

Lavender variety Hidcote is a summer mainstay © GAP Photos/FhF Greenmedia
Pink rose Cécile Brunner can break up the blue of lavender plantings © GAP Photos/Howard Rice

Another anomaly is that established gardens show less discomfort than newer ones. In London I see penstemons flowering earlier and more freely than ever they did in last year’s wet summer. Deutzias, roses, shrubby potentillas, salvias and now white-flowered hoherias have been smothered in blooms without flinching. Big-leaved catalpa trees have had masses of lovely white flowers, earlier and finer than usual. A prairie of grasses and yellow rudbeckias is not the only winning bet.

The sufferers have been new plantings and summer bedding. This spring I have been struggling with both. Like many of you, I was continuing to repopulate the garden after heavy losses in those icy interludes of winter 2022-23. Young perennials, planted out in early April, have been resenting the dry run since then. So have annual bedding plants, put out hopefully in late May. French marigolds and zinnias are familiar flowerers in hot gardens in Pakistan but they need watering every other day to stop them wrinkling their leaves and shrivelling. This year they have had no respite in which to establish.

Size matters too. Small gardens have retained a heavenly appearance in early mornings and evenings if owners have been following a watering routine. When the growing season began, water butts were full to the brim; when they fail, watering cans, filled from taps, are usually permitted when hose pipes are not. The routine has been a chore but is worth the regular effort. The most heavenly scent of June is released by white regale lilies in pots by a door; even in this dry year these and other lilies have been sustained by twice-weekly watering. When the hard glare of the early afternoon sun passes, the last of the day’s light brings out cool colours quite beautifully. 

In a big garden survival is patchy. It is impossible to water sufficiently by hand and keep an unshrivelled appearance. Instead, I adopt a mixed strategy, balancing a garden’s planting for summer like a balanced investment portfolio. Up to half of it is composed of drought-proof mainstays, perovskias and lavenders, but the other half is varied, majoring on plants with a degree of drought resistance which grow into other shapes and give finer colours. Here are three ways to identify good ones.

Grey and silvery leaves stop water from sweating out of a plant: no wonder they are prominent in dry Mediterranean climates. Look for low-growing artemisias, woolly grey ballota and the low-growing spurge, Euphorbia myrsinites. Dig grit, not gravel, round them when you plant them and check that your choices are hardy in winter, their alternative enemy. Some of the best silvery plants die in frost and need winter protection indoors; they are not fully hardy.

Campanula lactiflora offers milky blue flowers © Marianne Majerus Garden Images
Persicaria amplexicaulis Fat Domino flowers from July through August © GAP Photos/Elke Borkowski

Choose a backbone of plants with long taproots, central roots which thrust down and draw up and store water. Look them up before shopping as you will not identify them easily when they are out on sale in pots. Star turns in midsummer are tall verbascums, which make freestanding vertical accents in a summer garden when they are in yellow flower. Tall campanula lactiflora with pale milky blue flowers is another tap-rooted winner, as are early flowering Oriental poppies. The better knotweeds, not the Japanese invasive menace, are excellent in dry soils for the same reason, even in open shade. My favourite is Persicaria amplexicaulis Fat Domino with masses of fat red spikes of flower from July on through August.

Best of all are hollyhocks, tap rooters which are able to survive in narrow spaces near paths and gravel as a result. They will give height and seed themselves into cracks and gaps where you would never expect them to grow.

Beside tap rooters, choose fleshy rooters. Day lilies are winners here, as are agapanthuses and not-so-red hot pokers, or kniphofias. Their fleshy roots, too, retain water and reach out to find it. Consider white bindweed, that lovely “lily”, as country dwellers once called it. It has fleshy roots indeed, fragile and complicated to extract from a flowerbed, but as a result it thrives in dry summers, even in wild hedges. If it did not entangle and choke other plants it would be a wonder in the garden. Instead, it is a weed with a lesson: think about new plants’ roots, fleshy or not, and choose plenty of fleshies to vary the garden in dry or not so dry years.

Never be one-sided. Balance your choices and allow for seasons which will vary. Always expect surprises, not all unwelcome. My major bet is that gardening will continue to vary locally within a wider warming average. What fun; ingenuity is still needed.  

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