Thank you for all the links and educational descriptions of cold frame. Now that I've known more about it. It seems not a necessary thing in Houston since we only get a few days of freezing weather per year if at all. However, when and if I start to have a big collection it may become necessary. Sujit Hart Houston, Texas On Fri, Feb 24, 2012 at 12:31 PM, Jane McGary <janemcgary@earthlink.net>wrote: > Perhaps I should not mention my own work here, but in the book "Rock > garden design and construction," which I edited for Timber > Press/NARGS, there is a chapter on bulb and alpine frames,