Choose plants from list of plants that grow in clay soil.

When I plant in clay I dig a hole at least a foot in diameter and a foot deep remove most of the clay then add back 1/3 clay 1/3 steer manure 1/3 peatmoss mix well and plant a small plant into the hole . If you do that for each small plant what happens is the roots grow through the ammended soil and then break down the clay as they grow I live where we have very heavy clay soil and this works very well

Remove the old mulch and any other covering on the soil. Take soil samples of the clay to your local Extension Office Master Gardener who will help you get the soil tested so you know what to supplement the clay with to get the proper mix of organic matter and clay so things will grow in it. If you can tell them "this is a flower garden" or "this is where I want to grow turf" or "I want a vegetable garden here" they will adjust the soil supplements for that use of the area.

Once you get your report, go to your local nursery or home supply garden store and buy the necessary supplements and compost. You will either need to rent or buy a rototiller in order to mix the soil and the supplements in the ground, or if you want to do it by hand - lay a large tarp by the garden, dig out the area about 16 inches deep sifting any trash, roots, and rocks out of the soil/clay you dig out then put the supplements on the sifted soil and mix thoroughly with your shovel (similar to the cooking process of folding an ingredient in only on a much larger scale).

Do not listen to some people who will tell you that adding sand alone will solve the clay problem - you know what bricks are made of? Clay and sand! Clay needs organic matter added such as manure, compost, leaf compost, etc. to become good for growing.