raised beds

[aquilegia]

I'm planning to make some raised beds to go on the patio and drive way. So they'll be on a solid surface. I will of course make sure they drain well, but I wanted to know what height I should make them. They will be 2ftx2ft square (because that's the length of the wood I have). I'll be growing mostly perennials, wild (or wildish) annuals and bulbs out the front and veg in the ones on the patios (such as carrots, courgettes, salad and tomatoes - as overspill from my veg patch).

[aquilegia]

[saddad]

Either... at the most comfortable height for you to work... which depends on how tall you are... or if they are just planters what ever you want. 2' is good for deep rooting  plants, but the deeper your bed the more filling it takes...  :-X