Can I harden off tomatoes by opening the window

[PureBlackVoid]

I have 3 trays of tomato plants the window sill in my spare room. The windows are side opening, so will leaving them open be enough to harden them off properly instead of carrying them up and down daily?

The weather has perked up a lot these last couple of days, is it too early to start?

I guess it might work as an initial step, as it would drop temperature and humidity. But I don’t think it would toughen up the stems. Sunny days with a gentle breeze are best for hardening off tomato plants.

From the start of May I start hardening off tomato plants, after a week they live outside even at night unless there’s a risk of frost then they come back in the greenhouse.

Weather forecast is for another cold spell, isn’t it?

On a day like today they could be outdoors in a shady spot, and just brought in overnight.

Thanks all, the spare room is currently housing a flat pack kitchen as well so I was hoping to avoid climbing over the boxes daily and I’ve nowhere else to keep them inside😁

The weather has indeed gone back to normal today so think I’ll wait a bit longer just in case!