I have germinated tomato, cucumber and zinnia on sunny windowsills but now they are getting leggy and have their first true leaves. Can I move them into my cold greenhouse, the temperature of which drops to 3-4 degrees at night?
My Zinnia seedlings are in a cold greenhouse, I have a heater but its only set to come on when it drops to 5, even then it only emits heat in bursts and not full time. They are doing fine. Although if your seedlings are only little maybe keep them on the windowsill until they've got a bit stronger.
Hi Alex, if they have their first true leaves sounds like pricking out time. Pot on into individual pots choosing your strongest seedlings, use a dibber or pencil to make the hole and plant them lower in the soil. Keep them indoors until it gets warmer.
There's a good thread on growing tomatoes on here from Simon Knott with videos attached, I recommend taking a look.
Alex, sorry if my first answer seemed rude, but all those plants are not hardy, so should really not be in a cold greenhouse yet.
Pot on and keep indoors for a few more weeks.
I can't pot them on yet as don't have enough room for them - I always find it difficult to start plants off - once they're off, it's too warm in the house and too cold in the greenhouse.