Clay soil gardening takes time, patience and effort. Clay soil is heavy and dense, when it’s wet you can slice it into neat slabs, when it’s dry the spade hits it with a clang and won’t even penetrate. It is difficult to get plants to grow in this type of soil.
If you have clay soil in your garden you will need to work with it for several months before you can plant. You will need to dig in lots of organic matter and gravel every couple of weeks to break up the soil.
Clay soil does contain a lot of nutrients that will help your plants to grow, the problem is the drainage of excess water.
Clay holds water very well and can drown your plants if you don’t provide adequate drainage. If you keep digging in gravel you will get enough drainage to be able to grow there.
Once you have done this try to plant plants that have thick roots that go deep into the ground. These will hopefully penetrate through the remaining clay and further help the drainage.