How to go 12 rounds with clay and come out the victor

I recently did a gardening talk at Uffington and one couple, who’d moved just a few miles, have been struggling with their new garden because of the heavy clay soil. It has already destroyed the husband’s back, despite the fact that they only moved in in autumn.

They were also worried about what would grow. Clay, good for baking into bricks, is probably the worst soil of all to cultivate. On the plus side it is fertile and holds on to nutrients better than any other med-ium, so it’s not all bad news.

Some of the best gardens in the country suffer from sticky soil and this includes Great Dixter in East Sussex. The staff improve the soil by digging in coarse grit to some areas and they also add organic matter to lighten it up. When working on the ground they always pirouette on planks to avoid compacting the soil with their body weight. This is good advice with many soils and I use planks at Spring Cottage, although I hate to say this but I have deep, fertile soil without a stone in sight.

Clay lies cold and wet in the winter, so often spring is a little later. Once it arrives that is the best time to plant because the soil is warming up. Dig larger holes about twice the size of the plant root ball — sorry husband — because this will improve drainage. Add a sprinkle of bonemeal to encourage root production and, should it be a dry spring and summer, water regularly.

Beware of planting anything in autumn, because it will turn up its toes in a wet winter, and never dig a hole just the right size for the root ball on clay soil. You will create a sump that will hold water and kill your expensive addition. Always, always break up the bottom of the planting hole with a fork.

Managing and cultivating the soil needs a patient approach because the soil should be turned in autumn with a spade. The action of cold weather, freezing and thawing, should break the soil down and then you can complete the job (hopefully) with a fork in spring. Tap the clods to judge how willing they are. You will also find that not all parts of a garden are as sticky as some.

Once it’s more manage-able many things will grow, and the National Collection of Witch Hazels is held on grey sticky Kent clay (witchhazelnursery.com). The late Mark Trenear used to have a collection of dianthus on heavy clay in Hampshire. He dug out paths and tipped the soil on to the beds, raising them up to improve drainage. Batsford Arboretum, near Moreton-in-Marsh, splendid in cherry time, used to plant on mounds in their clay — although I’m not sure they still do this now. (batsarb.co.uk)

In order to stop the clay soil baking and cracking in summer, you will need to keep the direct sun from cooking the soil. You can mulch with garden compost, mushroom compost or green waste, but the best way is to plant densely so that the foliage excludes the sunlight. Among the woody plants that enjoy clay are viburnums, hawthorns (Crataegus), crab apple (try Malus x robusta Red Sentinel), flowering cherries (Prunus), hydrangea, buddleja and roses.

Among the easy perennials are most hardy geraniums and I recommend ‘Rozanne’, a later blue geranium that will cover a yard, so not for a very small garden. Asters generally do well (try ‘Little Carlow’), hellebores (H. x hybridus) love it, red astrantias, hostas, Japanese anemones, kniphofias and crocosmias also do well once established. Slugs will be more of a problem on clay, but most overwinter as eggs, so disturbing the soil in spring will expose the eggs — and robins love them. If the garden is sloping, so much the better, because this will drain water away from the top, creating a better growing medium. Snowdrops, narcissi, scilla and bluebells will all cope with sticky soil.

Go walkabout and see what’s growing in your neighbours’ gardens, because they are likely to have similar soil. If there’s a great open garden near you, look at that too for it will give you ideas. Avoid silver-leaved plants, because they will look a dull green on clay, likely as not.

Finally, plants do not read gardening books. If you want to plant something, try it out. I would never be growing witch hazels at all if I’d read about them first!