[header] How to build vegetable garden boxes [title] Make sure that your garden box will be able to drain. [step] Do not put garden boxes on surfaces that will not absorb the water that runs through your garden box. For example, tarmac and concrete are not ideal surfaces for a garden box. 
[substeps] If you plan to place the box on a surface that was previously turfed, remove the turf by peeling it back with a spade. [title] Add grit to soil that doesn't drain well.