Tomatoes-Temperature

[ken]

Infact I think it is about keeping the plants at 10C or above if at all possible. We're in a frost pocket so I always assume our temperatures will be lower than the local forecast. So I'm in the shuttle brigade, moving the plants between house and greenhouse everyday. Las year I bought a couple of large, square plastic drip trays from Homebase. They say not for carrying, but I think this is an over-cautious 'elf 'n safety' warning and the trays have handles on the sides. The trays will hold nine plants though I find six at a time is enough...

[freddy]

Hi folks.
Well, I planted them into the greenhouse border around 2 weeks ago, and so far they're making good progress. I HAVE had to put on some heat at night, which I could have done without. It seems to me that it's been a very cold spell over the last few weeks. Is this normal ? All part of the learning process, I guess. Next year, I'll try to resist the temptation to sow early. I have however got more plants on the go, so hopefully my cropping period will be extended. Over the last two years, I've lost my outdoor crop to the dreaded blight. This year I'm going all out to produce a later crop, so I'm gonna try Bordeaux Mixture.

Cheers...freddy.

[ken]

Hi Freddy. I think we're all in the same boat, and a bit of mutual sympathy is called for. This isn't a normal year. By now, I would expect us to be enjoying reasonably warm nights, with just the occasional drop in temperatures. In other words, I'd reckon on leaving the plants in the greenhouse overnight quite often, perhaps with a fleece covering, and only bringing them into the house if there was a threat of a late frost. Right now, even the day time tempertures are pretty miserable!

[freddy]

Hi folks.
Interesting to note that last night it dropped to 8.1C in the g/house. Does that mean I should have maybe waited until July to plant out ? Confusing eh ?

Cheers...freddy.

[PLUMPUDDING]

It went down to 5C last night in my greenhouse, but the plants look fine. The ones in the garden are still a bit blue looking as there was a frost the night after I decided it was warm enough to put them out. They've all got plenty of fruits on though and a few in the greenhouse are just starting to redden up. Can't wait for the first decent flavoured tomatoes of the year.

[Mike Vogel]

Yes, that' s interesting. This year, for the first time, I diddn't bring plants indoors at night, but left them in the unheated greenhouse covered up with sheets of bubblewrap. This seems to have been enough to keep the plants sufficiently warm, but I wonder whether they would have put on more growth if I had kept them warmer at night. All plants are doing finr, and the peppers are in flower.

[Compo]

I agree with the science of the 10c Barrier, and it is interesting that the tomato seeds lurking in my greenhouse bed have only just sprung to life after being shed from the tomatoes I forgot to pick that fell on the bed last year. Nature has its way and of course we are trying to stretch it an manipulate it by planting seed in greenhouses propgators and the like.

but I do have another thought on this, I think the plants must obviously be able to tolerate a wee bit of sub 10c temperatures because, well they do............mine have had minus 10c temps in the unheated greenhouse and the golden nuggets are currently bearing small green fruit. My theory is that we are talking about a sustained exposure to -10c hence the luck with bubble wrp / fleece etc. I do not take the plastic propagor lids off mine till they are well established and temps are ramping up.

If you think of a human in sub zero temps, he / she could survive for a while without protective clothing and not be damaged as long as he / she got back in doors from time to time.

Just a thought, oh and I know that humans and plants are different!!

CoMpO

[Geoff]

It is a good job they survive below 10 - most of the nights here recently have been nearer 5 than 10.

[Johnboy]

Hi Compo,
I do not think that anybody has suggested that they will not exist below 10C but 10C is the optimum for continual growth. Every time the plant is subjected to a temperature below that point it gets a check in its growth pattern. They eventually get to putting out a crop but that crop can be very vastly different had the plant been grown the the optimum minimum. Here the other morning the overnight temperature fell to 3.5C
and even the plants in the greenhouse simply didn't like it. My outdoor plants here are grown in pots here this year and are put into one of the tunnels at night. They are in pots placed on the bed of two trolleys so easily put to bed each night. They have two trusses set and are at flower fade for the third truss but the fruits are going to be quite small this year probably due to the cold temperatures.
JB.

[ken]

Yes, I agree with Johnboy. Temperatures below 10 are clearly not fatal to tomato plants, but can cause damage. I've said once befofe on the Forum that one year I got tiny little tomatoes on some trusses. When I queried this with the experts at Wisley, they said the embyonic tomatoes had been damaged by low temperatures. This year is a bit wierd too: one or two lower trusses haven't developed at all. The plants are now trying to catch up for lost time so I have three or four trusses of flowers open at the same time on some plants, and in some cases lower trusses are opening after higher ones.... But the plants are looking very strong and I think the crop will be OK.

[The Mouse]

Well I'm starting to get excited, because my first Sungold tomatoes are starting to get some colour. What's more, it's the ones which have been planted outdoors for the last month (not enough space for all of them in my little greenhouse) which are ahead, despite the chilly temperatures they have had to endure since they went out.

Actually, my theory on that is that the extra 'stress' of the colder temperatures has made these fruits develop more quickly - it perhaps triggered the plants to reproduce as quickly as possible!

That said, temperatures here haven't fallen below 5c since they were planted out. I'm very pleased that it didn't get any colder!