I always wished my name was Clay, then I could have made something of myself. A bad joke but always good for a “groan.” Speaking of “grown” many people struggle with growing in Clay. It’s not fun to work in either, when it’s wet it is heavy and uncooperative, when it’s hot and dry it is like concrete. My previous house was situated on sand and gravel with no moisture retention whatsoever. The house where I’m living now is thick heavy blue clay, the exact opposite. I’ve found it’s great for growing a lawn because of it’s moisture retentive tendencies provided I do three things: 1) Raise the deck on the mower to shade the crown of the grass plants in the heat of summer. 2) Use gypsum pellets twice a year. 3) Core aerate at least 2 to 3 times a year, for sure in spring and in fall. I’ve reached the point I’ve purchased an aerator that I can pull behind my lawn tractor.
Available pores and oxygen are very important to good root growth. In clay soil the particles are so small that soil becomes dense with limited to no pores and oxygen for good root growth. A good test to check your soil’s density before planting is to dig a hole about a foot deep and wide. Then get the garden hose and fill the hole with water. Come back a few minutes later and see if the water has drained through the soil. If it’s still standing at the level you filled it to, you have potential problems, your soil may be horticulturally challenged.
When planting I recommend the following to help you (and your plants) in dealing with clay soil. 1. Dig the hole as deep as the root ball, but three times wider than the root ball. 2. Be prepared to work in liberal amounts of organic matter, I like using Canadian Peat and Renewed Earth, a soil mix that includes rice hulls. Don’t use sand, sand and clay together = concrete. 3. The key is don’t throw good soil in a bad hole. Mix the existing parent soil (clay) 50/50 with your soil amendment back into the oversized hole you’ve dug. You’ll get better root penetration once the roots venture outwards. 4. Use one inch and no more of shredded mulch once the plant is in the ground over the top. 5. Finally, get yourself a root feeder. I use a Ross Root Feeder attached to a garden hose. Two to three times a year I will work around the plants, pushing the probe into the root zone. The force of the water and the nutrient cartridge mixed with the water does wonders for roots trying to make a home for themselves in clay soil.