I want to cut a small bed from the lawn near the kitchen door to grow a few
culinary herbs. The bed will be at waist height because the lawn is up
behind a retaining wall. The subsoil is solid red clay. The position is a
good sunny spot in SW uk. I want to plant mediterranean type Herbes de
Provence which I believe require a sandy well drained soil which I
absolutely do not have. The size of the bed will only be say 6' x 2' so I
don't mind a bit of digging out or buying sand or loam, but what is the best
way to ensure drainage between the wall and the clay, and what is a good way
to mix or obtain the correct type of soil (whatever that is)?

tia, Tim /w