I planted raspberries in spring of 2011 in my clay loam, in a low spot of my yard, too close to my maple tree. Needless to say, they haven't been particularly happy and I decided to move them. I built several 2'x4' raised beds (8" deep) and am putting them in full sun. The problem is, I don't have much soil lying around to mix in with the compost and peat moss. I went to buy bags of topsoil at Farm and Fleet (since Menards doesn't stock it now) and that said "blend of peat moss and sand". I thought, I can buy those separate for cheaper, if it's not real topsoil.

So, how do you think the raspberries will grow in a mix of peat moss and compost, with wood chip mulch? They are open bottom boxes, so the roots could perhaps penetrate the clay soil if they need to. Thanks!