I echo this question and was interested in answers, it's stupid to say it won't move coz it depends on lots of factors, I agree it's much better to secure anyway, that way you never have to worry, far better to be safe than sorry no matter what the location is.
We had one with toughened glass (so weighed a lot), well bolted down on to a slab base, but in a horrendous gale a few winters ago, several panes of glass were blown out and eventually the whole frame buckled with the force of the wind, allowing panes of glass to fly out, and you can guess the rest . Have to admit though, the base never moved from the spot! As we have a very exposed garden in the north of Scotland, we decided not to bother replacing it - I'd hate to have that clearing up job again! We now just have a little potting shed where I bring on a few plugs at the window in the Spring .
My mother had a geodesic dome greenhouse in the 1980s in Edinburgh, and said it was much better in the wind. I have no idea how easy it would be to buy one now, and doesn't answer the question of fixing it down, but it might be one possibility for people in very exposed locations. I am currently trying to work out the best base for my new greenhouse, and am veering towards a circumference of paving slabs on a bed of sharp sand.
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We had one with toughened glass (so weighed a lot), well bolted down on to a slab base, but in a horrendous gale a few winters ago, several panes of glass were blown out and eventually the whole frame buckled with the force of the wind, allowing panes of glass to fly out, and you can guess the rest
. Have to admit though, the base never moved from the spot! As we have a very exposed garden in the north of Scotland, we decided not to bother replacing it - I'd hate to have that clearing up job again! We now just have a little potting shed where I bring on a few plugs at the window in the Spring 
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My mother had a geodesic dome greenhouse in the 1980s in Edinburgh, and said it was much better in the wind. I have no idea how easy it would be to buy one now, and doesn't answer the question of fixing it down, but it might be one possibility for people in very exposed locations. I am currently trying to work out the best base for my new greenhouse, and am veering towards a circumference of paving slabs on a bed of sharp sand.