Top soil for garden border

[britishboy7]

We’ve got an area against the fence that’s 8m long, 0.9m wide and going to dig down about 0.5m to plant some small trees etc (decorative trees all no taller than 4-5ft). Will topsoil be best to use? And should we add anything for drainage too? Under the top soil or mixed in with it?

 

[sodthisforfun]

I wouldn't worry about drainage unless it floods there all the time in the rain or is boggy. Any topsoil will do, but personally I'd mix it with compost too, compost has more nutrients and also aids drainage (it dries quicker). Last year I created new beds and mixed it 50/50 and the new plants have thrived - including a plum tree