This time of the year is all about managing the timing of when you plant seedlings out in the garden. Do it too early and the plants will be knocked back by night-time cold. Do it too late and the plants become ‘pot-bound’ – that is, they have grown too large for their container resulting in tangling of the roots (and possibly bolting issues later on). I’m still too suspicious of the weather to plant out relatively tender plants like courgettes and squashes - by potting them on in to bigger pots, you buy yourself a couple of extra weeks where you can keep them in doors.
I sow courgette, squash, cucumber and pumpkin plants in large module trays but they grow incredibly quickly and need to be put in to larger pots within 2 weeks or so. Simply pop the seedling out of its module, put a little compost in the base of a bigger pot, place the seedling in carefully and then fill it in with compost. It pays to water the plants very well about an hour before hand, the seedlings pop out of the pots much easier then, and of course you need to water again after you have finished potting them on.