Chance of frost tonight.

[M+C]

Good day everyone.

We just got rained on over night and tonight there calling for -1 Celsius.
I don't really have a good means to cover my plants.
Will they survive a light frost?
They are starting to ripen up fairly good but I would like to not take them down.
Any thoughts.

 

[Alpine]

Much depends on the specific strain you are growing. Some can handle light frosts better than others. Covering with agribon (or something similar) will sure help.

pier

 

[Radagast]

They were just talking about that in robncars fluecure thread, check it out:

It did, wow. I'm maybe 400 miles north of you and I got no frost forecast for at least a couple weeks.

I push my luck. I have been burned before though. Tobacco doesn't freeze until around 29°F, so if it's forecast something like 34° with a frost warning, I ignore it.

 

[ChinaVoodoo]

If you can pick them and deal with them, it's a safe way to play it. If you aren't sure if they are ripe enough and can stalk cure, then it's ok. If you don't have room for everything, I would do another priming and hope for the best. In 2014, I picked at 0° with snow and I ended up with a lot of olive coloured leaf that never ended up worth smoking. Several other years, I've left it multiple times on wet - 1° and - 2° nights with very little frost damage.

Agricultural research has shown that tobacco doesn't freeze until - 2°, and that has been my experience; however others will tell you that you can't (edit) trust your forecast to be accurate to the degree.

Research also shows that if you get frost damage and the threat of future frost is gone, that it is best to leave it on the plant so the plant can repair itself.

 

[ChinaVoodoo]

FYI, yesterday I looked up the weather forecast and it gave me the Calgary forecast. I didn't realize it wasn't Edmonton. I decided I was not going to do a single priming and leave the rest. Luckily, I don't have to worry about it because my forecast is significantly better. But please, make your own decision here.

 

[M+C]

Thanks guys.
With the provided info. Im probably going to leave it.
It's only for one night, and it's a slight chance. The rest of the week is looking really nice again.

 

[ChinaVoodoo]

Thanks guys.
With the provided info. Im probably going to leave it.
It's only for one night, and it's a slight chance. The rest of the week is looking really nice again.

Keep us updated!

 

[M+C]

Hey. It's been a while but we did dip down to -1. The tobacco took it like a champ! All is well!

 

[deluxestogie]

You can assess the effect of frost on tobacco after the sun has come out, and stressed the leaf.

Bob

 

[skychaser]

What was your dew point?

 

[M+C]

Not sure. This happened almost 2 weeks ago.
There was frost but it was light. Damaged the squash and tomatoes but only slightly.

 

[ChinaVoodoo]

This is often the benefit of staying calm and calling the weather man's bluff. One little dip, even if there is damage VS two more weeks of ripening. Sometimes you have to pick, or you lose because the weather doesn't care about you. But this time worked out. Right on.

 

[ChinaVoodoo]

I've tried and failed to find the original research, but I'm fairly sure I have it memorized because this is an important topic for myself.

Research has shown that tobacco freezes at -2°C.
Tobacco which has reached -2°, or -3°, but is not refrozen, will recover if left in the ground.
Tobacco which has reached -4° will have terrible, permanent damage.
Tobacco which has frozen at - 2° will now freeze at -1°, and damage occurring in subsequent freezes is more difficult to repair.

 

[skychaser]

I've tried and failed to find the original research, but I'm fairly sure I have it memorized because this is an important topic for myself.

Research has shown that tobacco freezes at -2°C.
Tobacco which has reached -2°, or -3°, but is not refrozen, will recover if left in the ground.
Tobacco which has reached -4° will have terrible, permanent damage.
Tobacco which has frozen at - 2° will now freeze at -1°, and damage occurring in subsequent freezes is more difficult to repair.

Not at all my experience! 31f for 1 hour causes some damage on nearly every strain I have ever grown. If it goes to 30f or below for any length of time the damage is severe and most strains are ruined. 28f = compost pile. That's why I asked about the dew point. When I get my first frosts in September it is always in very dry air. I don't know what role humidity might play. I suspect a high dew point might be why you seem to have much diffident results than I do. I have never seen any literature on that. But any temp below freezing that will nip tomatoes or squash, which are two of the most sensitive plants I grow, also burns my tobaccos to some degree.

 

[ChinaVoodoo]

You grow way more tobacco than i do, so your testimony means something. But, the literature I was referring to has fit with my experience on tobacco. My tobacco has been more resilient than my tomatoes, for sure.

 

[plantdude]

Was in the low 70's here yesterday. Felt down right cold, the mosquitoes even thought so

I imagine dew point/ humidity would play some role in damage. Seems like we can get a damaging frost around here at about 34 on pepper plants. Just guessing our humidity probably averages in the 60-80% range that time of year, I know dew point would be more accurate to look at but I've never paid attention to that. What's the difference in humidity between Edmonton and western Washington?
We are in the same boat as @ChinaVoodoo, we usually get at least two more weeks of good growing weather after the first frost. Our hard freeze and gusty winds usually hits right in the middle of the 5 day public land modern gun deer season about Nov15th. Hunt the first few days in an area that's overgrown and you can't hardly see 20 yards, go back the next day and suddenly there are hardly any leaves on the plants and you can see 100+ yards, always a weird experience to have.

 

[deluxestogie]

I suspect that the low temp value is not as important as the duration at or below temps that injure leaf. Tender leaf (growth tip) is more delicate than mature leaf. Lack of air movement allows the temp to drop more rapidly in low areas than in moving air, but once the temp is at or below a temperature that injures leaf, that damage is accelerated by higher wind velocity.

Bob

 

[skychaser]

Day time humidity in July through Sept usually is in the teens and sometimes the single digits here in Eastern WA. Western WA is much wetter than the east is and temps are a lot more moderate. I commonly get 40-50 degree swings from the highs to lows, especially in August and Sept. Humidity greatly influences the amount of radiational cooling. People in the SW deserts know what I mean. I was once camped for a night in November in the Anza-Borrego. It was 82 that day and hit 22 just before dawn. Radiational cooling is also what causes anchor ice to form at the bottom of rivers under moving water in winter. I have seen it a few times here. China has probably seen it many times. Wind is usually a good thing for me on those iffy nights because it keeps the atmosphere stirred up and the cold air from settling.

Peppers hate cold. They seem to get burned by frost about the same as tomatoes. But they stop growing with night time lows at 40 or less and the fruit hardly matures anymore. Seedlings will just lay down if it gets down to 40 and often don't pop back up. Tomato and tobacco seedlings don't mind the 30's. As long as it stays above freezing. I had some of those plug in thermostats that kick on at 35 and off at 40 in my greenhouse for a while that turned on extra electric heaters. But I had to quit relying on those when I started growing peppers. Keeping it in the 40's is a must for baby peppers. After all my seedlings are out of the greenhouse in spring I fill it with peppers for the summer. Even with the doors wide open it will stay 10 degrees warmer in there, day or night. This time of year I close the doors at night. It makes a huge difference between my outdoor and greenhouse peppers in growth and maturing. I'll have to turn the heat on in there by the end of this coming week. I usually keep it going through October. By Nov the heat will run all the time and my electric bill shoots up! And the light level is getting so low its just not worth it any longer.

 

[deluxestogie]

plug in thermostats that kick on at 35 and off at 40

I found those worked well for small loads, like a heated dog water bowl, but they repeatedly failed when connected to the "milk-house" heater in my pump house. Now, when the remote thermometer in the pump house says it's getting too cold, I trudge out there, and manually plug in the heater.

https://www.tractorsupply.com/tsc/product/farm-innovators-thermostatically-controlled-outlet-2170275

Bob