What Temperature does, Broccoli, Cauliflower, Cabbage, Carrots, Romaine lettuce, Freeze to death dead.

[gary350]

What Temperature does, Broccoli, Cauliflower, Cabbage, Carrots, Romaine lettuce, Freeze to death dead.

Murfreesboro TN

 

[Meadowlark]

There is a text book answer for each of the above, but in my experience the actual death temp depends on several complex variables including soil nutrients, plant health, water absorption in the plants, and length of time at the low temp. Hence, in my opinion, there is no absolute one answer to the question.

Soil Nutrients: Without question, plants grown in highly nutrient dense soil are more tolerant of low temps. I have seen synthetically fertilized plants consistently expire at higher low temps than naturally fertilized plants.

Plant Health: Plants that have been weakened by insect damage and/or disease(sometimes unseen) are much more susceptible to damage/death from low temps. This factor alone can make a difference of several degrees in the low temp tolerance.

Water : Plants that are high in water absorption do better than otherwise, especially in temps in the 20s. Temps in the teens, it may not be as much a factor.

Time : 15 deg. F low temp for an hour before sunrise is no comparison to all night at that temp in the amount of damage it does to the plants.

Further I have observed that some plants started from seed in the ground rather than started elsewhere and transplanted do much better at low temps. Onions are a good example of this.

Because of the complex set of variables there is no one answer for each plant. Here is my own garden experience for each plant mentioned by the Op (all temps in F):

Broccoli: damage at 22 deg. and death below 19 degs.

Cauliflower: damage at 31 deg. and death below 27 deg.

Cabbage: damage at 20 degs. and death below 12 degs.

Carrots: damage at 20 degs and death below 14 degs.

Romaine : Damage below 24 degs. and death below 19 degs.

Another I have years of experience with are onions. I have had onions take about 50% loss at 10 degs that were started from seed. Transplants 50% loss at about 15 degs.

 

[YumYum]

My Flat Dutch cabbage made it fine through a 21F degree night this time of year. Spring plants can be a bit more sensitive since the roots are not as deep which I think helps them survive, especially onions. Ditto for my Iceberg lettuce I had growing while in the Spring my Black Seeded Simpson leaf lettuce seedlings killed off at 19F.

 

[Oliver Buckle]

the roots are not as deep which I think helps them survive,

A good observation, there is a good case for saying the roots are the main part of the plant and above ground is simply food and reproduction, and soil is a pretty good insulator.

 

[gary350]

My 35 broccoli are starting to grow heads I hope we get a good harvest before cold kills the tops. Last winter I hilled soil up around broccoli 12" tall like a row of potatoes tops froze off at but plants under the soil did not die at -7 degrees, plants grew back about April 1 and we got 1 more harvest. Google says below 25 kills broccoli.

Last year cauliflower never grew a crop it seems to grow slower than broccoli top froze off. I hilled soil up 12" high plants grew back April 1 but never grew any cauliflower. Google says below 25 kills cauliflower. I hope to get a harvest before 25 deg this plants appear to grow slower than broccoli.

We had no Dutch cabbage or Napa cabbage last winter Google says 25 kills them.

Google says below 15 kills carrots. Last year carrots were in 10 gallon pots they froze and died. If I had pulled carrots the day before they froze they would have been good to eat. In the past I never grew carrots in pots. This year my carrots are in hills like potatoes, tops can freeze off and carrots under the soil are still good if I dig them up the day of the killer freeze. I just never knew for sure what the killer freeze is???????

I hope I don't have to pull or dig up 4000 carrots early this year. I never grew this many carrots before. Farmers Co-op had $8 carrot seed packs 2 ounces of seeds = 40,000. seeds. I planted all 40,000. seeds about 4000 grew.

The science of freezing says, 25 degrees with a clear sky is colder than 25 degrees and a cloudy over cast sky. I understand over cast clouds holds down the heat and it is not possible to have frost but 25 degrees is still 25 I don't under stand that? 25 degrees with no clouds is colder than 25 degrees with clouds.

Now that I know the target killer temperatures I need to keep a close watch on garden temperatures. My thermometer near the house aways reads 2 degrees warmer than the garden 100 ft from the house. If I swap thermometers its still 2 degrees warmer near the house.

We are zone 7a Murfreesboro TN.

 

[Meadowlark]

So, why did you ask the question if you already had the answer ?

Did you even read my response which described the complexity of the answer and the variables that can make a substantial difference?

Google says below 25 kills broccoli.

Google says below 15 kills carrots.

 

[gary350]

So, why did you ask the question if you already had the answer ?

Did you even read my response which described the complexity of the answer and the variables that can make a substantial difference?

I read all that. There seems to be several answers. Google is generic answer. Down to 25° is a safe zone.

 

[big rockpile]

Mulching helps some stuff.

Next year I'm planning on planting Carrots pretty late, mulch them and dig almost all Winter. When they get woody quit digging and let rest go to seed and collect it.

big rockpile

 

[Anniekay]

My 35 broccoli are starting to grow heads I hope we get a good harvest before cold kills the tops. Last winter I hilled soil up around broccoli 12" tall like a row of potatoes tops froze off at but plants under the soil did not die at -7 degrees, plants grew back about April 1 and we got 1 more harvest. Google says below 25 kills broccoli.

Last year cauliflower never grew a crop it seems to grow slower than broccoli top froze off. I hilled soil up 12" high plants grew back April 1 but never grew any cauliflower. Google says below 25 kills cauliflower. I hope to get a harvest before 25 deg this plants appear to grow slower than broccoli.

We had no Dutch cabbage or Napa cabbage last winter Google says 25 kills them.

Google says below 15 kills carrots. Last year carrots were in 10 gallon pots they froze and died. If I had pulled carrots the day before they froze they would have been good to eat. In the past I never grew carrots in pots. This year my carrots are in hills like potatoes, tops can freeze off and carrots under the soil are still good if I dig them up the day of the killer freeze. I just never knew for sure what the killer freeze is???????

I hope I don't have to pull or dig up 4000 carrots early this year. I never grew this many carrots before. Farmers Co-op had $8 carrot seed packs 2 ounces of seeds = 40,000. seeds. I planted all 40,000. seeds about 4000 grew.

The science of freezing says, 25 degrees with a clear sky is colder than 25 degrees and a cloudy over cast sky. I understand over cast clouds holds down the heat and it is not possible to have frost but 25 degrees is still 25 I don't under stand that? 25 degrees with no clouds is colder than 25 degrees with clouds.

Now that I know the target killer temperatures I need to keep a close watch on garden temperatures. My thermometer near the house aways reads 2 degrees warmer than the garden 100 ft from the house. If I swap thermometers its still 2 degrees warmer near the house.

We are zone 7a Murfreesboro TN.

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Get ya some row covers. That will help keep frost off and keep your veg growing for longer in cold weather.

 

[Oliver Buckle]

Get ya some row covers. That will help keep frost off and keep your veg growing for longer in cold weather.

sections of plastic water pipe make an excellent, cheap support for a cover, you can stick a bamboo in the ground and slide the pipe over it each end.

 

[big rockpile]

My son had some Tomato Plants they was doing great through frost but yesterday it got in the 20's that was just too much.

I don't think Row Covers will help below 30 on some things.

big rockpile

 

[Meadowlark]

... don't think Row Covers will help below 30 on some things.

big rockpile

Correct. Actually, in my experience on many things.

 

[DECEMBER]

Water freezes at 32° F. If the temp is at or below that for more than a day, they won't last long.

 

[Oliver Buckle]

Water freezes at 32° F. If the temp is at or below that for more than a day, they won't last long.

They can take it a little bit lowe. That's pure water, but a few sugars and salts dissolved in it the water in the leaves will lower the freezing point a bit.