Hi
For my carrots / root veg i have used the big plastic water tanks, the type you have in your loft. (my partner works in the plumbing trade and brings them home for free if they have been damaged / spring a leak! as i am only going to drill holes in them for drainage anyway.
These are great for me as my allotment is on a brand new site that was originally a mine. The ground is on the clay side, so until I can improve the soil and brake it up a bit I'm going to grow root veg in containers.
