Living in Essex and working in the garden industry, I know first-hand how much of a problem heavy clay soil can cause. From unwanted waterlogged/boggy areas to compacted unhealthy lawns, it can cause a real problem for clients and landscapers. But there are ways to improve these conditions by certain methods that have been used for centuries which make it possible to grow what you wish, whether it be crops or ornamental aesthetically pleasing gardens with a diverse range of plants.
Clay soil can get very wet as it holds a lot of moisture in its dense particles. Clay soil can also get really dry in hot weather, creating cracks in lawns and soil which will lead to plants wilting and dying in drought.
When realising you have to deal with clay soil after an inspection as a garden designer, you will need to decide what you will want to plant in that area and whether that is practical and functional for the client. Then you can decide either to work the soil to improve it or to work with the soil as it is by choosing plants and trees that would thrive in a heavier clay soil. The benefit of doing some work on the soil is that you would have a much wider variety of plants and trees that you could choose from, but depending on the budget that may not be an option.
One way to improve clay soil is to reduce the density of particles by breaking up the material with loose particles such as sand, horticultural grit or gravel, all of which would enable water to drain through more easily leaving the ground less wet.
You could also break up the clay with organic matter which has bacteria and living organisms that can break up particles which can add to the soils nutrients. Another way to tackle clay soil is use compost and soil improvers on the market. A combination of all three elements in the soil, sand (loose particles), silt (denser particles) and organic matter with nutrients would be the perfect mix. This is typically called a ‘loam’ mix and is suitable for a wide array of plants that can be used in the garden.