they will need to grow a lot bigger yet these are just the seed leaves. They need direct bright light so if you can, put them in full light.
they are hardy so I would put the pots outside during the day and in doors at night for a week and then I would personally plant the whole pot where you want them to flower.
I usually scatter the seed direct into the ground where I want them to flower.
hope this helps.

Thank you for the reply

They are straggly for lack of sun. These are prairie flowers and they need hot, dry, sunny conditions with lean gritty soil. No fertilizer for these, Leave them in the pots for now, but move the pots outside into the sunniest part of your garden or where you plan to plant them out. Acclimate them before transplanting them to reduce shock. Let them be outside in their natural environment for a week or so but with sufficient water so they don't dry out too much. After a week or so, you should notice quite a change - looking as they should. Then you can plant them out into their permanent location. Also, get a couple more seed packets and cast them over the ground and water in. This will extend the garden a few more weeks of blooms.

just a thought: is this the small annual blue cornflower that used to be a common wild flower in our fields here in the UK?

If it is not the annual one then you are going to have an awful lot of perennial plants.

Thank you for the reply they are perennial

I am guessing the are Centaurea montana then. google that name and see if that is a match for what you are growing. if you still have the seed packet does it give you their botanical name and/or a photo?

if it is them then what you have in one pot will need to grow until you can see roots coming out of the bottom of the pot. these are fully hardy in the UK and self sow in my garden regularly.
then using pots the same size as you have them in now carefully break the compost apart so that you have one small plant in each bit of compost. pop that into the middle of a fresh pot of compost. gently firm down and water well.

The name of the cornflowers is Blue Ball

Isn't Blue Ball an annual?

Thought it said perennial on the packet

Strange. Which brand of seeds are they? Mr Fothergill's say they are annuals.

Will check them tomorrow, you could be right

I grew Blue ball a few years ago and it is an annual.
So get the pots out during the day, in at night for a then plant a whole pot direct into your borders or troughs where ever you want them to flower.

Thanks for info

Thank you all who replied to my question, I have checked the seed packets and it does say they are Hardy Annuals, where I saw perennial I don't know.