When weather becomes warm and sunny, its time to start damping down the floor of the greenhouse in the morning, splashing water over it to increase humidity levels in the whole glasshouse. Reducing problems with red spider mite which favour a dry environment.
Start growing plug plants in your greenhouse. These are a cheap supply for a large numbers of plants.
Now is the time to prick out those seedlings before the tray gets too over crowded, pot them on as individual transplants as soon as they are large enough