I researched how to build a keyhole garden, and these are a couple of documents & pages that I relied on the most (although I didn’t believe everything I read). Click the photos to enlarge.
Building It
Summer Crop
Tomatoes, Leaf Lettuce, Basil, Carrots
Winter Crop
Broccoli, Cauliflower, Brussel Sprouts, Romain Lettuce (red & green), Carrots