I am constructing a largish rose bed in my garden. I have marked out
and am removing the turf, well more matted weeds really. The "soil"
beneath is very poor, consisting of clay and sand mixed with many
pebbles of various sizes, it is impossible to dig without loosening with
a pickaxe. If I dig in plenty of horse manure would this suffice, or
need I remove a spit deep and then replace with imported top soil?