I was recently asked how to plant in clay soil.
Here are some options.
First off, kill off the grass and weeds. You can cover the area with a tarp or newspaper/cardboard or use a herbicide. Use a lawn mower with a bagger and remove all the weed seeds and waste. You don’t want to have to battle the weeds during that first year.
The easy way to plant with a clay soil base is to cover the area with 6 to 12 inches of a good soil/compost mix. You plant in the soil mix and not the clay soil. Over time, the roots and earthworms will break up the clay soil.
Another option is to plant native seeds in the fall. Make sure the seeds come in contact with the soil. The above are Asclepias tuberosa seeds I planted last fall. I then cover the seeds with a soil mix so that the seeds are covered and will germinate easily in the spring. Native plants don’t need or want good soil for growing.
If you have the time, energy and money, you can dump lots of compost onto the clay and till it in. You can then plant directly into the soil. Unfortunately, in the process of roto-tilling you will bring up dormant weed seeds and will have to battle the weeds in the spring.
The final option is to make a hole for each plant and throw away the clay soil. You can then add a potting mix to the hole when you plant. I have used a large bulb planter in the past with this technique and it works well.
When the plants are growing well, you can add mulch to help with the weeds and conserve water. I usually add a mixture of compost and mulch every year to help feed the plants and improve the soil. Note – I found out that the mixture I got was very hot and killed most of my grass in the center.