tomato tolerance for cold weather

During the last week it has been horrible weather in finland.

I live in the south in Helsinki, but the night temperatures have been just torture for your average tomato hobbyist.

My thermometer in the greenhouse has shown the following night temperatures so far in the last 3 nights:

4 - 3.9 -  6 degrees centrigrade. Day temperature did not rise much above 10C.

Tonight the forecast shows 8 degrees centrigrade for the night. Day temperatures are now closer to 15C.

I have moved everything in pots inside: 62 big plants (also includes chillies, peppers and aubergines). Some already close to 1.5m tall. (i can't do anyting any more in my living room: no room left).

I built a fleece protection around my tomatoes outside on my allotment. I have 25 plants there. They range in size from 30 cm to well over a meter in height. Most are already flowering and a quarter of them have tomatoes growing.

My questions (finally).

Does anyone have any experience with this kind of weather and tomatoes? Can they recover from this kind of weather? I always assumed that they need at least 10 degrees centrigrade as minimum temperature.

Or can I basically give up on them and transport some of my plants at home to my allotment once the weather picks up? Or in other words, how quickly can you notice whether tomato plants have suffered irreversible damage from cold weather? We are not talking seedlings here. Most of the plants are pretty developed already.

The cold weather came a bit unexpected. Previously it has been  20-25 degrees centrigrade during the day. I guess it shows you just can't trust the weather.

But I could be worse. A bit further north it snowed.

A minimum temperature of 10C is only a rule of thumb for tomatoes and many other tender crops - whether they survive lower temperatures than that depends on how much lower, for how long, how mature and healthy the plants are, and also the temperature patterns when it does rise above 10C (huge variations between day and night temperatures will stress them even if they don't drop below 10C.)

A bad sign is if the tomato leaves literally turn blue with cold - they will really struggle to recover from that.

I don't select varieties for cold-hardiness, but there are plenty (many of Russian origin) which are short-season types, although that doesn't mean they will withstand really cold conditions of course.

A US site HERE with a few suggestions.

Hope yours recover OK - that's a lot of plants you've got there!

i think a lot of us have a few scary moments with temperatures at the beginning of the season.

personally i think you'll get away with it, it's only been a couple of nights below 5 degrees and the lower daytime temperatures will help. i think it's the swing of low to high temperature and back again that does the damage.

fingers crossed.

That really is so disheartening 

I don't have any helpful suggestions but just thought I'd sympathise.

Spuriousmonkey, I highly recommend a forum called Homegrown Goodness and specifically a poster called Joseph Lofthouse. His season sounds not dissimilar to yours, long winters and brutal but quick summers.

This thread may be worth a read:
http://alanbishop.proboards.com/thread/6988/tolerant-tomatoes-right-josephs-alley

This is all very interesting.

Maybe I should just see it all as an experiment and see if there are any varieties that pop up as more cold resistant. I have plenty of Russian varieties out there on the allotment that are meant for growing outside in colder climates. Ironically this is the first year I didn't grow subarctic plenty. Maybe this would have been finally the year it could shine.



The weather forecast shows that temperatures should go back to normal at the end of the week.

Maybe there is an end in sight.

I guess I was lulled into a false sense of security with the temperatures the past few years. That's because last year it was 5 degrees above normal average in june. The previous years were also warm, but this year it is 5 degrees below average!

Next year I will actually start planting most of my tomatoes much later. I have one variety that I planted two months after the first ones. The plant is actually similar in size right now than all the other plants. The only difference is that the earliest plants have more flowers and that many of them have already fruits.

I will seed a few plants early, but most later. It will cut down on the logistic nightmare. I will still have early tomatoes, but with less work. A compromise.

If the weather clears up at the end of the week, I will move 10 to 15 of my potted plants to my allotment. I won't pull out the existing tomatoes unless they are obviously dead. You all made me curious. I want to see how they cope with this kind of weather stress. I still have plenty of space left on my allotment.

And next year I am going back to 50 plants. It's just that I had the typical rush of "get as many varieties as you can" madness during the winter.

I guess as long as you learn from your experience it is not a wasted experience.

The other thing i learned from this experience was to realize how fragile the life of a farmer must have been, and still is. Some years things just don't grow. And if it is your livelyhood than I can sincerly empathize with your feelings.

I had a quick look today at the allotment how the tomatoes are doing.

The once I had protected seemed to look still ok. I was actually surprised to see how well they still looked.    The ones without any protection looked pretty miserable (only 3 small plants).

It's still early day to say they will make it through, but maybe some of them at will.

If all is fine the weather should get better in a week's time. Fingers crossed.