Last year I experimented with biointensive gardening and companion planting. It was my first time and I followed my hunches more than study the established facts and methods. The results were quite good; beginner’s luck, I believe.
I’m reading more on companion planting this year and planning the garden more carefully. The stormy and cold weather of the past couple of weeks, discouraged me from taking the seedlings into the garden as I had prepared to, and instead provided time for me to study more.
Here’s an edited printable chart PDF which covers most vegetables and herbs. And here are a few useful pages with charts which I drew from:
http://en.wikipedia.org/wiki/List_of_companion_plants
http://www.gardensablaze.com/Companions/CompanionYield.htm
I haven’t finished designing the garden yet, but I’m getting close.