Designing Gardens on Gravel (& clay & chalk & silt)

Our part of South London can be tricky for gardeners due to the different types of geology and hence soil in a relatively small geographic area. We've seen super sticky clay soil at Sho

Charlton geology ! Sand used for glass, gravels for ballast, clay for bricks & chalk for mortar.

oters Hill, gravels in Blackheath village, chalky Westcombe Park & silty riverside Greenwich gardens! Add to that historic human activities such as farming, building and the Luftwaffe (!) which again creates a varied mix of soils.

The upside is that we have very varied planting within SE London which is good for local biodiversity. But the downside for individual gardeners is that it can be hit and miss regarding plant selection if you don't know what soil you have. Moreover, for design work its important to assess the soil and sub-soil if possible regarding any structural

work that requires foundations such as walls or load-baring surfaces.

Top and sub-soil exposed at a SE7 project

As well as a prior knowledge of the local soil type, we usually do a soil test both pH and structure. Also check what else is growing around the site and its health. While its a sample, this can at least give a good indication as to the site soil situation. Needless to say odd things do happen like pockets of builders rubble or even the occasional iron double bedstead buried below!