Growing celery! First time

This is my first year of growing celery and it is time to plant out. I have an allotment with carrot, parsnips etc and a greenhouse. I was going to plant my celery in the allotment but unsure whether to because of rumours. I have heard that they are not good near carrots and that they need to be kept well away from slugs. We havnt had any slugs lately but get quite a lot if were not careful. Could i keep my celery in individual pots in the greenhouse? If so how big would the pots need to be?

Thank you for any advice   

As long as my celery gets a space in the garden and lots of water, it's happy no matter where it grows. Only trouble I've had is a bit from earwigs. Once the plant is hardened off it can deal with cold weather quite easily so no need to keep it in the greenhouse.

Just to add that a plot neighbour used empty 1l fruit juice cartons with the top and bottom cut off over her celery plants. The plants quickly grew up and out of the tops of the cartons and absolutely thrived

I'm going to give it a go as it was much easier than my previous method of tying up the stalks into  a bundle using soft string 

This is my first year of growing celery and it is time to plant out. I have an allotment with carrot, parsnips etc and a greenhouse. I was going to plant my celery in the allotment but unsure whether to because of rumours. I have heard that they are not good near carrots and that they need to be kept well away from slugs. We havnt had any slugs lately but get quite a lot if were not careful. Could i keep my celery in individual pots in the greenhouse? If so how big would the pots need to be?

Thank you for any advice   

They would need to be pretty large pots if you grow them in the greenhouse and the plants can get quite large much larger than the ones you buy in the supermarkets which have been trimmed and made pretty and have probably been grown hydroponically as well so they will be smaller. They will take up a lot of greenhouse space, probably more than you think.
But they are REALLY worth the effort as they taste like a totally different vegetable than the ones in the supermarket. If you keep them well watered as another poster has said they will be crisp and sweet and  you will always want to grow them every year. You don't need to mess about with trenching these days as there are self blanching varieties and white celery is only a fashion anyway because they taste just as good with green stems. But the secret for success is the watering. I grow mine in the lowest part of the garden that always stays a bit damp and even then I water them as much as possible. They will quite happily sit with their roots in water as they are a marsh plant. If I were you I would dig the area out that you intend to plant in to about a spit depth and plant them so that any water you give them does not run off and stays where you want it.
But then with the water you attract the slugs which can be a real pain. This year I am going to use those non poisonous pellets to keep them in check. I don't want to kill my hedgehogs with metaldehyde (sp) poisoned slugs. But even if you do get slugs all is not lost because there are usually a few stalks that they haven't munched and the ones they have you can use for making soup as the brown stains don't matter when they've been well washed and liquidised. I have tubs of celery soup in the freezer made from rejects and you can use the leaves too.

They are not frost hardy and will need covering later on when it gets to that part of the year but if you are only growing a few you will probably have eaten them all by then.

It's a great vegetable. Enjoy.