posted 10 years ago
If you've got poor drainage, may I suggest radish? I've used a layer approach to heavy clay that goes like this: small twigs/leaves/thin branches, followed by horse manure (somewhat aged), followed by a sprinkling of radish and clover seed, covered by about 1/4-1/2 inch of bark fines. In the first year, this resulted in lush growth. That fall we knocked it over, and covered the downed vegetation with more horse manure, probably about 4 inches. The following spring we grew squash there, which did outstanding. No tilling or broadforking. The radish made roots that were 1 to 2 inches in diameter, which punched numerous holes in the clay.
8 inches of compost is enough for many annual edibles to grow well in without ever having to punch through the clay. We used to do 12 inches of horse manure over clay, then simply plant. It worked well, but not great, it's better to have a cover crop first.