Vegetable garden of the (super) lazy in the 04 (800m)

[lemur]

There are two concepts:

a) the minimum temperature of the soil for there to be germination, which you should know that this is not a number set in stone: there are sometimes significant varietal differences (lettuce); for the same variety, it should be understood that an indication like "minimum germination temperature: 10 °" means that at 10 °, the majority of seeds germinate, within a reasonable time; below, it germinates again but less or less quickly or both!

b) the temperature tolerated by the seedlings, once they have emerged; there, it is the risk of frost which is the fear; namely: in general, this limit increases when the size of the seedlings increases (therefore the more developed seedlings are less resistant - I know, it is counter-intuitive and yet logical for the living!).

Another notion would still be the "zero vegetation": the temperature at which there is no more growth! Higher, of course ...

The question I ask myself is:
If the air temperature is (artificially in the chests) correct for the plant, what about the soil temperature?

Does a correct temperature of the air in the chests necessarily induce a correct temperature of the floor in the chests?
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The temperature of the air outside the boxes being very cold, style -10, the ground outside the boxes being also very cold, does it come to cool by "capillarity" the ground inside the boxes?

And consequently at what soil temperature do the roots of tomatoes pass the weapon on the left?

I'm sure I'm wrong, but I think that the cold air in the trunk could only cool the earth if it lasts a long time, a long absence of sun for example.
I think on the other hand that by capillarity it cools, or the fact may be to put the plants on a polystyrene type insulation or other.

[Adrien (ex-nico239)]

I'm sure I'm wrong, but I think that the cold air in the trunk could only cool the earth if it lasts a long time, a long absence of sun for example.
I think on the other hand that by capillarity it cools, or the fact may be to put the plants on a polystyrene type insulation or other.

If I have too cold air, that is to say which kills the plants in the trunk, it is not even worth it.

If I manage to keep an air temperature inside the chests that does not kill the crops (this is already the case for beans and peas for example) what will be the temperature of my soil in the trunk interior: influenced more by the “cozy” interior of the trunk or the “frozen” exterior

[Did67]

You can't reason like this: the minimum air temperature your plants can tolerate is very variable! Winter wheat tolerates -20 ° C. Winter lettuce, some cheeses, leeks are not far from it!

Other plants are very sensitive. My sweet potatoes "broiled" in my absence, and it didn't freeze! Green beans, it's gone with a razor: a few small "rolls". The tomatoes resisted. Like escaroles, all kinds of cabbage. Turnips. Fennel. The onions. The carrot seedlings did not flinch ...

The ground is a buffer: it is colder during the day, but "recharges". It is warmer at night, and recharges the air.

The temperature gradient depends on the soil. The speed at which the thermal front "advances" is called effusivity ...

If you want to "model" that, you can hang on! A good thermal engineer, if given the effusiveness and the heat capacity of the soil could undoubtedly do it.

But let's be silly and pragmatic:

a) for resistant vegetables, the question does not really arise seriously! The main purpose of tunnels / frames / chests is to force them ...

b) for sensitive vegetables, in my opinion, it is generally the aerial part that will be limiting ...

c) by - 10 ° approximately, on January 2017, XNUMX (from memory), my ground was not frozen under the hay ...

[Adrien (ex-nico239)]

the minimum air temperature that your plants can tolerate is very variable

b) for sensitive vegetables, in my opinion, it is generally the aerial part that will be limiting ...

c) by - 10 ° approximately, on January 2017, XNUMX (from memory), my ground was not frozen under the hay ...

Of course.

My question (and my ignorance) arises (for example) for tomatoes.

Example
If the air is at 3 in the trunk and at -10 outside and the floor at 3 outside .. what about the temperature of my floor in the trunk?

And starting from there
If the air temperature allows the tomatoes to survive in the trunk
Can the temperature of the ground kill them?

[Adrien (ex-nico239)]

some news

Tomato seedlings
The advantage of the tubes: the big space saving indoors
We manage about thirty "plants" in a box of cookies
I tried to take them out immediately upon emergence when they are still white and put them in “full” sun.
But it's the October sun so even if it's beating (+ 30 in the sun at the moment) no damage a priori.
The box of cookies is filled with water: it avoids watering, it heats up in the sun and since I leave them outside until almost overnight, it keeps the heat while the cold falls outside.
Then direction artificial lighting until around 2 a.m. for a total exposure to light of around 18 p.m.
What I'm going to do with it: I don't know.
Finally if put some in chests and see how it behaves and if it holds because the lighting there will be significantly less
I'm afraid I did it a month too late but hey we'll see.

If it doesn't hold up to the brightness level, I will take it up in a tube and transplant at different sizes to see what works best and in the end up to how much it holds with and without additional protection (bell)

There are other tests already in place: photos to follow and video later

In short, there is bread on the boards.

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The same in position, too bad it is "hot" minimum 4 at night.
The first night went well
I positioned 3 tubes while waiting for the cold

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A second in another chest

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Brussels sprouts a little at all stages (must be one or 2 Alsace in the lot)

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lamb's lettuce seedlings

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lamb's lettuce growing

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A box of future radishes (sown) and a little lamb's lettuce (where there is no hay) which dates from 2017 and which grows back every year.
The concern is that it's either too cold (and it doesn't grow all winter) or too hot and it goes to seed too quickly in the spring, so we hardly benefit from it.

It must therefore be protected in winter so that it grows without climbing and then shade it in the spring.

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[Did67]

When is the "natural emergence" (the seeds which "hang around", as soon as you uncover the soil) chews in your house?

A difference between the "Italian" chews [those with large leaves, say "with large seeds"] and the "shell" type cheeks [from the north of France / Blegique]? The seconds are much more resistant but smaller ...

[Adrien (ex-nico239)]

When is the "natural emergence" (the seeds which "hang around", as soon as you uncover the soil) chews in your house?

A difference between the "Italian" chews [those with large leaves, say "with large seeds"] and the "shell" type cheeks [from the north of France / Blegique]? The seconds are much more resistant but smaller ...

I wasn't watching too much anymore ... basically, at the end of September I would say.
In all the places where I sowed it in 2017 it proliferates but we do not profit much for the reasons given above.

When spring arrives she is still small and by the time she gets older it is too hot.
But in the spring I observed that the one who grew in the shade of the small bales of straw and therefore who never saw the direct sun of the day grew normally.

When the large square will be in operation again (perhaps from this season) it will therefore be necessary to provide for very early shading

[Did67]

Ditto for germination ... Shade !!! I fortuitously saw a crazy difference between a seedling on bare ground (after harvest of pot), I throw the seeds, I trample. And in one place, I put a large bunch of parsley mounted in seeds (to peel later). True to myself, I forget. Result two weeks later: a very dense lift under the bouquet ("like the hairs on a dog!"), But disparate, much more spread out, elsewhere ... You have to achieve a sort of "skeleton" ...

I have massive spontaneous emergence every year along the blackcurrants, as soon as the cover is thin ...

It is a plant that grows under the others ...

[Did67]

For those who read German and want to progress in winter vegetables, this book based on the experience of an experimental garden in Vienna (Austria).

With a preface by Coleman.

Too bad everything is so "clean" - nothing is ever perfect.

You can browse a part on Amazon and see the images ...

2020-10-30_19h04_49 Températures mini.png (701.08 KiB) Viewed 2508 times

I translate the legend to you:

"We do not find systematic scientific data (numerous) concerning the hardiness of vegetables. Chinese salad varieties [it's Mizuna] - related to Chinese cabbage -, such as the" Red Streaks "variety here, are credited with resistance. at temperatures of - 5 ° C. Our tests have shown that these plants tolerate temperatures of - 14 ° C. without damage.

This ties in with a remark I had already made about the unreliability of certain data.

[Adrien (ex-nico239)]

For those who read German and want to progress in winter vegetables, this book based on the experience of an experimental garden in Vienna (Austria).

With a preface by Coleman.

Too bad everything is so "clean" - nothing is ever perfect.

You can browse a part on Amazon and see the images ...

2020-10-30_19h04_49 Températures mini.png

I translate the legend to you:

"We do not find systematic scientific data (numerous) concerning the hardiness of vegetables. Chinese salad varieties [it's Mizuna] - related to Chinese cabbage -, such as the" Red Streaks "variety here, are credited with resistance. at temperatures of - 5 ° C. Our tests have shown that these plants tolerate temperatures of - 14 ° C. without damage.

This ties in with a remark I had already made about the unreliability of certain data.

Ah too bad I do not read German ...

Afterwards, as I often say for the lamb's lettuce, you have to be aware of what "withstands temperatures of -X" means.

The lamb's lettuce example is quite educational.
Lamb's lettuce has been taken every year for 10 years with us and it is still there (we could also take the example of clary sage which comes out at the end of summer and only unfolds for 4 or 9 months. later)
So the temperatures don't kill her.

And after?
What interest for the consumer?

It doesn't die but it doesn't grow.
Result we can not consume it
No interest.

What would be interesting, however, is that they GROW by -10 and that we can therefore grow it productively in winter.
But this is not the case.

On the other hand no doubt that by protecting it from the very cold and even by giving it a little warmth we can manage to take advantage of it in winter.
But in this case, in principle, its resistance to -10 is no longer of any use to us except in the bizarre case where the temperature would drop to -25 occasionally and to -10 under the greenhouses / chests which would mean that the production would not be lost.

In short, what matters to me if we want to produce is production temperature with small lower tolerances in order to guarantee punctual and extreme cold snaps.

On the other hand, the minimum temperature supported is interesting if the goal is not production but just winter conservation, that is to say keeping alive for a hypothetical recovery advanced in spring.

And then we don't invent anything, the elders took care of it for us: sowing tomatoes in October