Celeriac - growing conditions

Has anyone any experience of growing celeriac in a polytunnel. I do reasonably well with celeriac in the open plots and have a few spare plants and wondered if the polytunnel will be too hot for them if I put the spares in there when the new potatoes come out.
Any thoughts, anyone please. Ditto celery as I have a few plants spare of them as well.
R

I read somewhere they need plenty of water for the "bulb" to grow

At the moment though, mine seem to be doing very well outside - they are about 6" tall.

What the secret to getting a good crop - I do think I planted mine out too early they were pretty small and in this heat a large % had shrieveled and died - I did have some seedlings left in the tray so I potted these on today, thought some fresh compost will give them a feed and I will wait til they are bigger before planting out so any tips will be gratefully received as they are my OH's favourite.

Thanks
Missy