Topic: Stressing Tomatoes

[MikeB]

Stressing tomatoes is done by exposing them to the cold and I have done this for the last four years, trouble is I can't remember why.  So the question(s) is why do you stress tomatoes?, how long for? and at what period in their life cycle.

[Curryandchips]

Isn't stressing done to activate the fruiting process, as the plant reacts to a threat to its existence. Hence a thermal shock could produce more flowers, with hopefully more fruit ...

[MikeB]

The stressing I'm refering to is done when the plant is only 4-6" high, so quite young.  I've seen it refered to in various texts and it is always reccommended, but the text acts as if you already know why you're doing this and as I say I've forgotten.

[supersprout]

Hi Mike
As a tomato newbie, I've not come across this idea yet - do you have examples from the texts? My books don't seem to mention it anywhere!

In an American book on raising artichokes from seed, it's claimed that if you plant early Jan, you should chill the young plants in March and warm them up in April. This tricks them into thinking they've endured a winter, so they produce flower heads for eating and can be treated as annuals (this must be the part of the US where it's too cold to overwinter them). But I can't see a connection with toms!

When my mum grew tomatoes in her greenhouse in Northumberland, we often got strong plants with only green trusses that we wanted to ripen before the Autumn. They were deliberately put under stress by chopping the roots three quarters of the way around the ring culture pot. This did the trick, but we didn't call it 'stressing' so far as I remember.

[MikeB]

Of course I can't remember a single article  ??? ???,but if you go to

https://www.reneesgarden.com/articles/grow-tomato.htm

and look at stage 12 it is referenced there.  A found a number of references to trimming roots in searching for more info on the cold stressing, it's called believe it or not..........

root stressing  :D :D

MikeB

[supersprout]

LOL who'd a thought it eh ;). Looking at the weblink, the cold stressed seedling looks erm, weedy. She says:
"Remember that seedlings need to be kept at about 65 - 70 degrees after they have true leaves and until they are ready to go into the garden".

Do you think cold-stressing might be something to avoid? :o :o ::)

[jennym]

I did read some research on the effects of temperature on tomatoes. Evidently, the uptake of nutrients by the tomato plant is affected more by the temperature around the root area, than by the air temperature, although of course any air temperatures at around freezing would damage the plant.

It appears that nutrient uptake is better in plants that have more heat at the root area - this need not be artificial heating, it was seen as an effect of growing in the ground, which would hold the heat better than a pot, all other things being equal. It was seen that when temperatures fall from high during the day to cool at night, if the ground holds the heat well, the nutrient uptake was better than if the overall temperature was constant but lower.

There is also research on the effect of cold on flower formation too - it seems that once the tomatoes have around 4 true leaves, if they are exposed to temperatures below 8 degrees C for any length of time, then there is an effect on flowers, a sort of malformation which results in smaller fruit and lower yield.

However, before this point of growth, exposure to temperatures down to 10 degrees C can result in stockier plants, there is a growing system used commercially to control growth which subjects the plants to temperatures around 10 degrees in the morning after a higher temperature at night.

[MikeB]

As a recap Jenny would it be fair to say. Subject the tomato plant to a low temperature of 10C in the morning before it has 4 true leaves. e.g. when it has two leaves?  This will then give a sturdier plant

[jennym]

Erm, yes Mike, I believe so  ;D

[tim]

Ours get stressed enough when they get frosts for some time after planting out - in the 'house!

[Trixiebelle]

I stress my tomatoes every year. They seem to do well from stressing as long as I don't get them TOO anxious. I say things like:

YOU KNOW I PLANTED BOLTHARDY BEETROOT @ THE SAME TIME AS YOU ...

YOU'RE NOT DEVELOPING AS WELL AS MY LITTLE GEMS ARE YOU ..

OK! SO YOUR LITTLE SHOOTS ARE APPEARING ABOVE THE SOIL. SO THANK ME!

RED ... RED ... CALL THAT RED??!!!!!! I'VE GOT BURST VEINS IN MY EYES REDDER THAN YOU!

But I love them really!

[rosebud]

Hahahahahahaha!!, Trixebelle, that is exactly what was going through my mind just before i read your post, ;D ;D ;D.  Only i might add Grow or you will end up in the bin. ;D ;D real stress!!!.

[Robert_Brenchley]

That's rather my approach as well. 'Think you can get away with not growing do you? Well, I won't have plants taking the mick in my lessons, so you either get on with it or do an hour's detention. And if you don't pull your socks up after that, you'll be in isolation. So just get on with it, and I'll say no more, OK?'

[MikeB]

I suspect that the last three posts are taking the p**s, ;D ;D ;D, but as I'm not certain I'll let it pass.

Anyway I've found what the process is:
Vernalization - Chilling to induce early bloom, hence earlier tomatoes - It must be done early, when the first true leaves are opening up and the plant is only 1 1/2" tall.  Night temperatures of 10C to 13C for two to three weeks are usually effective.  Not all vegetable specialists agree that his method makes sense.  If you decide to try it, treat only part of your crop so that you will have some unchilled plants for comparison.

From ' The new seed starters handbook ' by Nancy Bubel

[supersprout]

If you're going to experiment mike, will you post your results later in the year? VERY interesting! :D

[MikeB]

If you're going to experiment mike, will you post your results later in the year? VERY interesting! :D

I think I'm already doing this, my greenhouse drops to 5C most nights so all my toms are being stressed.  I don't have any unstressed ones for comparison, but this time I've kept notes when I planted, when they germinated etc. Perhaps we can compare times, I let you know how many days it took to flower from germinating and you could do the same?

[rosebud]

NO, Mike, we are not taking the wee wee, just having a bit of silly fun . First day of spring that is whats doing it, just made me laugh stressing tomatoes ;D ;D ;D ;D ;D
No offence meant at all, Cheers Rosebuddy. ;D ;D

[Curryandchips]

Well I have just had a very enjoyable ten minutes re-reading all these posts in this thread. An unsuspecting visitor stumbing on these posts must think us stark raving bonkers talking about stressing tomatoes !!! And our sincere interest and deliberation would only make them more convinced !  :D I speak from a position of direct experience, at work, they consider me certifiable, wanting to spend early mornings at the weekend in a damp field ! Long may it continue !!!

[MikeB]

NO, Mike, we are not taking the wee wee, just having a bit of silly fun . First day of spring that is whats doing it, just made me laugh stressing tomatoes ;D ;D ;D ;D ;D
No offence meant at all, Cheers Rosebuddy. ;D ;D

Hi Rosebud,

Absolutely no offence taken, I was joining in.

[supersprout]

I let you know how many days it took to flower from germinating and you could do the same?

OK Mike, I am going to keep notes now - I sowed my tomatoes yesterday, and they will be the first entry in the 2006 Captain's Log :o :o

Thank you for the prompt - I wouldn't have got around to it and know how useful these retrospectives are :D