However much it rains, a rubbishy stony soil dries out in no time. A couple of warm, windy weeks and it’s dry again. Hardest to cope with in drought is sandy or gravelly soil: soil that turns into a fine beach, its spaces that were once filled with water now full of air and the plants’ roots themselves dying of desiccation. It’s why I moved from Essex, where I had a garden on the River Granta, with 10ft of packed flint shingle below it. That was dry! It was hard going, like builder’s rubble or the sandy, pine-covered landscapes of Surrey and Norfolk.
But how do you cope with such powdery, gritty or sandy soil? Above all else you give it masses of compost, anything to build up some humus in there. When you plant or dig it over, you always pile in the compost deep down as well as at the top, then you mulch it with more compost. If you don’t have compost you use leaves, maybe pinned down with a sprinkling of grass clippings; it keeps in the moisture and gives the worms something to take down.
At worst, you can mulch with fresh hedge clippings, although that will require a sprinkling of nitrogen-rich fertiliser such as sulphate of ammonia to stop the decay robbing the soil of nitrogen. And you must add compost even in a wet year to keep building up that humus. Frankly, you must compost every scrap of vegetable matter that you can, fine-shredded hedge clippings included, even if they take a couple of years to rot down. It will never go to waste.
If rainfall is sufficient, shrubs that sucker (Mahonia, Pernettya) will stand firm in rubbishy soil, but it doesn’t offer much anchorage to plants with a single stem and a heavy top. Brooms and lavender, for example, will thrive in extremely poor soils, but stand up best when they have developed in situ as seedlings, getting their tap roots deep into the sand before they make much heavy top-growth. So if you are planting in loose soils, it’s always best to put a small plant into a very well-prepared hole. Putting a large rootball of peaty compost into sandy soil is the worst of all possible worlds; it is the perfect recipe for making the plant waggle at the crown and in strong winds it may tear at the root.
With little humus or fine clay particles to hold the nutrients, you will find sandy soils very hungry. Even if you are growing plants suited to drought you may still find that they are small and lean. To achieve lushness you must feed regularly with artificial fertiliser. But be careful: if you overdo it the weight of poorly anchored top growth will make a plant fall over; nothing goes over like an over-fed, rain-sodden broom. Yucca, on the other hand, has a big grey rosette to stabilise itself all round.
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Lousy soil is not all bad. Sand is wonderful for plants that need perfect drainage around their necks, especially in a wet year, even if they take a year to get their roots down and thrive. Nerines love it and throw up masses of lipstick trumpets in autumn. So does Amaryllis belladonna. Euphorbia characias stands tall and firm and sea hollies think life’s a beach. “Yeah, but it’s rained all week,” you say. Well, that’s the point: on sandy soil it just disappears again, like a rabbit down a hole, then you are back to dry soil before you know it.
The best plants for dry soil
Euphorbia characias
Broom (varieties of Cytisus, Genista and Spartium)
Ceratostigma plumbaginoides
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Cistus spp.
Rosa pimpinellifolia
Artemisia ‘Powis Castle’
Abelia x grandiflora
Box
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Aucuba
Ceanothus
Coronilla
Lavatera olbia
Rosemary
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Lavender
Thyme
Rosette-forming plants
Yucca
Houseleeks (Sempervivum)
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Tap-rooted or perennial plants
Valerian
Sea-holly
Erigeron
Agapanthus
Horn poppy (Glaucium flavum)
Toadflax (Linaria purpurea)
Flax (Linum)
Catmint
Macleaya cordata
Stachys byzantina ‘Lamb’s Ears’
Tall sedums
Californian fuchsia (Zauschneria californica)
Blue lyme grass (Elymus arenarius)
Bulbs
Allium
Gladiolus byzantinus
Zephyranthes candida
Amaryllis belladonna
Nerine bowdenii