I am trying to get hold of some rockery stone - there was a small-ad in the local press for 3 cwt free. But no-one ever answers the phone. It's our local hard stuff, Kentish Rag, a limestone cemented sandstone which comes in irregular chunks. It is now difficult to source, so I was rather pleased to see the ad, and intend to pay the owners if it hasn't already gone.

The stone I have in the garden is a mishmash of the previous owner's rock specimens, and mine, and a load of smashed concrete. I did look up how to make hypertufa, but decided that the concrete - known among geologists as "urban conglomerate" or "wimpeyite" (Wimpey's being a major construction company) was very similar, especially if mossy. However, it will be difficult to construct a rockery which looks like a natural outcrop. Ragstone would be much easier.

Penny