[Spookess]

Hi everyone. Newbie to the forum and newbie allotment plot holder here 
I have set some seeds going on my windowsill at home which are doing great, but the ones in my heated propagator that the packets said needed constant heat (sugar baby watermelons and various tomatoes) have shot up to the point where the watermelons are touching the lid and most of the tomatoes have fallen over.
As this is the first time using this I was wondering what I have done wrong 
Should I have removed them from the propagator as soon as they germinated? 
I have positioned it in front of a sunny window and turned it daily so they didn't all bend towards the sun - now they couldn't bend  more if they tried! 

Any help/advice would be great fully received.

[AndyRVTR]

Once seeds have germinated they should be removed from heat and put somewhere with decent light but warm enough if they require it.

[Spookess]

Once seeds have germinated they should be removed from heat and put somewhere with decent light but warm enough if they require it.

Dang it! Luckily I have more seeds as been looking forward to those watermelons 

Thanks 

[Yorkie]

Even on a windowsill and turning them, it's worth putting a piece of cardboard behind it with foil on it, to reflect light back onto the seedlings.