Sunflowers - what size pot?

[SiouxsieSiouxStiletto]

I've got some Sunflower seedlings ready to go out when the frost risk has gone. I've changed my mind about where I want to put them though and now they will need to be in pots.

I've read that they only need a 20cm pot. That can't be big enough surely?

Depends what type of sunflower you've got. If it's a giant then you're going to need a much bigger pot. If it's a smaller variety then obviously a smaller pot, but I've never seen a sunflower in a pot as small as 20cm

I thought it seemed a bit small too. Glad I checked before buying them.

Think I might be going back to my origin plan of sticking them in the front garden.