How many beds?

How many raised beds should we have? Our back garden is fairly spacious, maybe 7 metres wide by six metres deep, with a 1 x 4m chunk taken out of it for the compost pile. We also have a large front garden with a lot of bed space, but the beds are fairly irregular and have trees and shrubs here and there, so I don't think that will work for large containers. Having said that, there is one patch of bare grass beside the chicken coop which would fit a 2m x 1m bed and allow plenty of sunlight at the plants.

This is the layout that I'm currently considering for the back garden. Each 2m x 1m bed will be divided up into nine 33cm squares, allowing for 18 different plantings per bed.

The bottom edges of beds 2, 3, and 5 will have trellises to support tall plants (most likely tomatoes) and allow them to get sunlight without shading the rest of the bed.

Beds 1 and 4 will be partially shaded for most of the day, because of the tall fence and trees which belong to our neighbour. I expect we can put something like lettuces in there and protect them from the worst heat of the summer.