I grew up in Essex and then lived in North London for many years, so I became very used to gardening on heavy clay soil. Seven years ago we moved to Suffolk and I suddenly found myself in a very dry and windy area of Eastern England, gardening on light free draining soil. My, what a difference the soil makes!
Clay has a bad reputation for being a difficult soil to cultivate but it does have its good points too. If you garden on clay you will know that it is very sticky and this is because the clay particles are very small and stick together in great lumps. Clay soil also holds a lot of water making it heavy to dig and slow to warm up in spring, and in summer it shrinks and cracks.
The plus side of clay soil though is that the tiny clay particles can hold on to plant nutrients such as potassium, magnesium and calcium. This means that these nutrients don’t get washed out of the soil and are available for the plants to use, so making clay a good nutritious soil. Providing you improve the structure of a clay soil by adding plenty of organic matter such as well rotted farmyard manure or garden compost you can, with time, grow a good range of garden plants.
A sandy soil has very different characteristics. Sand particles are much larger than clay particles and have an uneven shape so allowing water to drain away quickly. This means that the spaces are filled with air rather than water making the soil lighter to dig and allowing it to warm up more quickly in spring. This sounds rather good but the downside of a sandy soil is that the sand particles cannot hold on to plant nutrients so these are quickly washed away and any organic matter you add is quickly broken down. A sandy soil is a thirsty, hungry soil. So how do you decide what will grow in these two very different soils?
Once you have analysed your soil the next thing you need to note is the aspect of your garden, that is, which are the sunny areas and which shady, and then you can start to select your plants. Begin this process by checking out where each plant comes from. Plant origins can be found in a good plant encyclopaedia such as the RHS A-Z Encyclopaedia of Garden Plants. If a plant comes from a sunny, dry rocky area in Turkey then alarm bells should ring if you had hoped to grow it in a shady, north-facing border on damp heavy clay.
In your garden you should always be striving to grow together those plants that originate from similar habitats. It doesn’t matter if they are from different countries. Providing they all require similar growing conditions then they will with time look like a natural plant community. Think how satisfying this will be for both you and the plants. Try to avoid making impulse buys at a garden centre. Do your research first and go out with a list of plants that are suited to your particular growing conditions.
When I gardened on heavy clay I found that trees and shrubs grew well and evergreen shrubs such as Viburnum tinus, Pittosporum tenuifolium, and Arbutus unedo all flourished as did the summer flowering shrubs, Philadelpus ‘Belle Etoile’ and Weigela florida ‘Variegata’. They all enjoyed the moisture and nutrients in the clay soil.
Herbaceous plants were rather more difficult to grow as many of the popular plants such as echinaceas, rudbeckias, Verbena bonariensis and Gaura lindheimeri tend to come from North American prairies or countries with Mediterranean type climates and they will quickly rot off during the winter in cold wet clay.
They are all very happy however in my sunny Suffolk garden on free draining soil. Herbaceous plants that did thrive on clay were the aconitums (monkshood), heleniums, Anemone x hybrida (Japanese anemone) and most of the perennial geraniums such as Geranium ‘Rozanne’, all plants that come from areas of the world that have a fair amount of rain.
Spring bulbs were quite difficult too as many of these come from hot dry regions. Tulips for example are found on rocky slopes in Turkey and the Middle East and these were best grown in containers. Narcissus are more tolerant as they come from mountain valleys in India, China and Japan where they get a fair amount of rain and cultivars such as ‘February Gold’ and ‘Thalia’ will grow well in clay.
On a light free draining soil, especially if it is windy, trees and shrubs can be difficult to establish. Evergreen shrubs that do well are Elaeagnus x ebbingei and Phillyrea latifolia and angustifolia. Buxus sempervirens (box) seems to grow well in any soil and box spheres suit most styles of garden so this is a great plant to give structure and rhythm in any garden.
Trees close to British natives such as Sorbus aria ‘Lutescens’ (a cultivar of our whitebeam) and Pyrus nivalis a pear that is found growing in rocky places in Europe both do well. Silver and grey leaved shrubs such as lavenders, Phlomis italica, santolinas, and Euphorbia characias will all thrive.
You are almost spoilt for choice when it comes to herbaceous plants and grasses and many will seed around providing a wonderful tapestry of summer colour Gems such as Dianthus carthusianorum (Carthusian pink). Erigeron karvinskianus, Sedum ‘Purple Emperor’, Echinacea purpurea and Verbascum phoeniceum hybrids will all seed generously. It is also worth trying annuals such as Orlaya grandiflora, and the opium poppy Papaver somniferum as if left to seed they will return next year filling in the gaps in early summer.
Whatever your soil and growing conditions, providing you check out your plants carefully putting the right plants in the right place you should be able to have a very successful garden.
Take a look at Hilary’s 8 week online course: Professional Planting Design Course with Hilary Thomas at MyGardenSchool: http://www.my-garden-school.com/course/designing-with-plants/