Can I put my tomato seedlings into a greenhouse (unheated) now?

[user1471530109]

They've been sat in my windowsill for what feels like months. Probably more like 6-7 weeks. Can I move them into the greenhouse now? I have no heater in there. First year of having a greenhouse so apologies if this seems a ridiculous question.

I would wait until may personally. The weather's always a bit wonky in April.

It's up to you. Check the forecast for any frosts.

I just have. But they were in unheated conservatory so not to much of a shock. And there’s no frost forecast for the next week

No, I wouldn't. I tried this last year - kept some on the windowsill, put others out to "harden off" in my unheated greenhouse. I had several varieties, as I went a bit mad in lockdown and had about 14 tomato plants so I could afford to experiment.

The ones I kept indoors, even though ultimately I transplanted them later, were far more successful plants. I would definitely wait until May

I would wait as long as you can - I'm in SE England and my young tomato plants (past seedling stage now) are struggling a bit in their unheated greenhouse; I've hardened them off but they are not enjoying the temperature fluctations (~3 degrees at night then 16+ during the day).

Luckily the temperatures are forecast to be reliably in the mid-teens and milder at night from early May onwards.

Maybe I'll bring some of mine back in then. But I'm running out of space!

Saw on another gardening thread that this is an unusually cold and dry April (especially overnight). You could try having tealight heaters (in terracotta flower pots)?

Thanks everyone! Looks like I should leave it another week (or even two). It's dipping to 3 degrees here most nights still.

When I do decide to put them out there, do I need to do it in stages? Like when hardening off?

Yes, get them used to daylight temperatures first, bring them in at night for the first couple of nights if it falls below 10 degrees (which it will until at least mid-May). Then you can start leaving them out all day and night in the greenhouse. When it’s reliably above 10 degrees most nights then you could get them out of the greenhouse, by which time they should be starting to flower anyway and attract pollinators.

Mine have been in for a few weeks and have just put them in gro bags today. I started by bringing them in overnight on a tray, now I have a phone reminder to close the door at night and reopen it in the morning, they’re looking very healthy.

I have a bed in the greenhouse (soil, not sleeping) rather than pots and I think that that keeps things in it warmer. But I also drape fleece over seedlings etc, put in a couple of short canes and drape fleece over so it isn't touching the plant and reaches the soil.

Fleece is a good shout. I should probably get a thermometer to keep an eye on how cold it gets in there for a few nights before putting them out. How cold can they tolerate?

When I said seedlings, they really are proper plants now. I think I started them off in February some time. I also did far far too many plants and hoping to give a few away if they all stay as healthy as they are now. I've got a few different varieties on the go.

Can they stay in the greenhouse? Or do they need to be out for pollination? Can you tell I am a complete novice . I have grown tomatoes (even from seed!) before but never in a greenhouse. I've also got chillies, peppers and cucumbers on the go ...I'm very excited!

I am going to go against the majority and say that they will be fine. Mine have been in an heated greenhouse from the start. It's been down to just below zero in there on a few nights and they are doing just fine.