Would help if I knew what part of the country you were in, and quite what you mean by a large number. Do you have a greenhouse?

Live in High Wycombe 500 ft above sea level and the start of Chiltern hills.

No greenhouse but 2 weatherproof but unheated sheds. circa 50 plants bought this year.

Have a look at Four Seasons and work back from the wedding......that might give you a few ideas on winter protection that they use to keep up the stock in a garden opened to the public.

Well I know that High Wycombe can get jolly cold, and that's an awful lot of plants. Bear in mind though, that pelargonium geraniums will tolerate up to ten degrees of frost without any trouble - what kills them is winter wet, which causes them to rot. Your shed might work, but only if it has a supply of daylight - they will still need some light, can't be kept in total darkness. If you decide to put them in there, cut back topgrowth by half or two thirds, dust them with sulphur dust (garden centre) and keep them pretty dry - they'll probably only need a tiny drop of water after a couple of months, but inspect them regularly. I've stored mine before in a box on the wardrobe in an unheated bedroom and not watered them at all until I repotted in late February/March, when I did water to start them into growth, moving them to a brighter situation too. The important thing is to not let any leaves fall onto the soil and stay there - remove immediately, they will rot and cause fungus.

many thanks for your advice

Brian

I guess they's survive well in an unheated coldframe if they're kept very dry Bamboo?

I've always brought a few pelargoniums indoors in late autumn and if treated well they'll flower all year around. This year I intend to try to overwinter 50-100 plants so I'll try the coldframe idea. I didn't realise they could cope with 10 degrees of frost.