Tomorrow I plan my weekly call on our nearest micro brewery. I expect to collect a dozen bags of spent hops free of charge which I will take round to the allotment where they will become stock in our shop, to sell to members at 20p per bag.
On the local sticky clay soil spent hops have a dramatic effect. When spread on the surface and lightly cultivated in, it will make the soil in your bed much more friable after a couple of months.
I have also found them to have a beneficial effect when preparing planting sites for top fruit and soft fruit. I remove the top soil, and fork the hops into the compacted clay subsoil, then replace the topsoil and let it all settle before planting.
I have heard that the Eden Project in Cornwall, in an old china clay pit, uses spent hops from the local St Austell brewery.