When you have clay soil, improving it is job #1.  I’ve dealt with both grey clay and red clay.  In the organic garden the best way to improve the soil is adding organic material.  One of the major problems people run into when they try to fix clay is that they don’t go far enough.  Clay is wonderfully nutrient and holds water like a sponge, but it has a hard time with drainage.  Before you start digging think about what is going to happen to the water that goes into the hole you just dug.  If you are planning to dig you want to dig a large area and possibly add some drainage.  Don’t just dig a hole that is 2 foot wide and 6 inches deep.  You won’t really be doing much good.  Dig an entire garden bed at once … a large one.

If you don’t want to mess with possibly screwing up and having to fix your drainage you might want to think about building an easy no dig garden bed.  This entails placing a lot of organic matter on top of your soil and planting in it after it has turned to compost.  This does work and it will improve your soil.  You need to put several feet of some sort of organic mulch down and just let it sit there and rot.

If you decide that you want to go ahead and dig or till up your lot you will need to get a hold of as much organic matter as you can.  Fall leaves, compost, and anything else you can come up with.  You’re going to dig it deep and add a lot of the stuff you’ve gathered to your soil.  A good technique for incorporating organics into clay is to use the backbreaking technique known as double digging.  Double digging works great for your soil and will give your body quite a workout also.  If your organics are already broken down you want to put a 2 – 4 inch layer onto the soil prior to double digging.  I’m a little strange and must admit that I love to dig.  I might be part badger but you give me a shovel and I’ll dig all day.  It may scare my neighbors but keeps me off the streets.

I’m not going to get into the sand controversy.  I have added sand to my clay and I’d do it again if I didn’t have more organic material than I know what to do with. 

A final option is simply to plant and keep a constant layer of mulch on your soil.  This will improve your soil slowly but it will get better as the mulch decomposes and is replaced.  You should add new mulch annually.

Quick Tips and Tricks about Clay:

Never walk on wet clay soil
Don’t walk on your garden beds
Water deep but not often
If you want to dig and the soil is too dry and hard – water and wait 3 days before digging

Sources and Resources about Clay Soil

Natural Resources Conservation Service
Organic Gardening
Fine Gardening