Light soils that are stony or sandy are often dry because water drains quickly and freely due to the particles which make up the soil structure being large. This often mean that plants can suffer from a lack of both water and food as nutrients get washed through quickly.
Like our feature in the last issue on soggy soil, the key is to embrace your soil condition and work with, not against it.
The best option is to choose plants which will relish light dry soil, rather than trying to change the soil to suit the plants. Look out for drought-tolerant plants which have water-storing fleshy leaves, or silver, hairy, or waxy foliage to minimise water loss like sea kale, Crambe maritima, with its waxy, grey-green leaves.
There is a huge range of plants which will thrive in dry soil including easy-growing shrubs like Buddleja davidii which does well in part-shade; perennial summer blooms like Dianthus and Geum; the Mexican fleabane, Erigeron karvinskianus, which will self-seed freely in sunny or part-shade locations, and of course a range of swaying grasses like Stipa gigantea, with its tall, airy flowerheads.
If the area is dry and sunny, make the most of it by choosing plants which would be often considered borderline hardy plants in colder, wetter areas of the country. Think southernly Mediterranean climes and plant lavender and rosemary with their aromatic foliage which copes well in impoverished soil and their small, waxy leaves which reduce moisture loss.
You can even have roses in a light, dry soil with Rosa rugosa being one of the few roses that likes those conditions. Choose ‘Alba’ or ‘Rubra’ for large white or bright pink flowers followed by those gorgeous red hips.
Improving the structure of light soil is easier than with heavy clay soils, and it starts by adding plenty of organic matter to boost the water and nutrient holding properties. Using home-made compost or even well-rotted manure, dig it in to a depth of 1-2 spades before planting and put down more every spring as a no-dig mulch to keep the soil in good condition.
Adding a soil improver like biochar will afford long-term benefits for light, depleted soil. Biochar is made from woody waste by a slow-burning process and it holds on to nutrients, beneficial fungi and microbes, boosting plant root systems.
When planting, fill the hole with water and allow it to drain before planting in order to encourage roots to penetrate deeply straight away in search of moisture.
Create a ground covering of foliage to retain moisture in the soil by using plants like greater periwinkle,Vinca major, a trailing spreader that will cope in most tough spots, even in dry shade.
If we make the right choices, light, dry soil in Scottish gardens can host an abundance of fabulous plants.