Repotting melons - how big and how do they grow?

Thank you. They are now in individual 14litre pits, so I hope they do ok. I have got them in the garden as it's so warm but I can move them into the greenhouse if needed.

I think it depends on what kind they are.
We grew them twice in France and even there in the very hot wet summers they never became very sweet.
I think they were canteloupe. Also once we grew watermelons.
Foliage spreads quickly on the ground which is why I liked them as they covered the weeds. like courgettes and pumpkins.
In the UK I would repot them separately each in a large container anf keep them in a greenhouse, or one of those that you make with shets of glass on a wooden frame.
lots of water as J52 says.

We have grown them in the greenhouse and put them in a deep 40 cm pot, with a climbing framework.
When the fruit develop they need a net to support them. We keep the nets that oranges, lemons etc come in, for this purpose. They need a lot of water and we feed them with tomato feed.

They'll need a big container each. I think they would climb if you gave them a sturdy framework but the fruit would need supporting,(if you get any).

I'm not sure they're very suited to our climate.

Anyway, Google is your friend

The leaves are enormous, you could use outer ones as an umbrella.
I haven't grown melons but a few years ago I put some parrot seeds in my D's garden one May and it grew a large gourd which was used as a lantern for Halloween.

They're happy in the ground and better too given the speed of their growth.