I am not a gardener, but still found this book to be quite useful. I bought it when I worked at Sooke Harbor House, one of the world's top hotels with a gourmet kitchen that focuses on using only seasonal local and natural ingredients.
This book is an excellent resource, stuffed with specific information about vegetables, herbs, fruit and edible flowers. I found it very handy to know when I can get fruit from a plant twice in a year, what parts of some plants are edible, what seasons things were available, and how weather would affect the flavor and usability of upcoming crops.
There is a lot more detail in the book that i have never used: managing plant beds, crop rotation, pruning tips and other cultivation tips and guidelines, so it would be very useful for a gardener. For me it was quite a good resource, and I recommend it to anyone who has the same interests.