I put my tomato plants outside here in the Midwest last week and they have been doing well with our unusual warm spell. Now they are predicting night time temperatures of the low 40's. I will try and cover them with plastic, but am curious to how much cold these tomato plants can survive.
I'm in zone 2 (3 in a good year).
Tomatos don't do frost. I
f it's freezin' the tomatos are seizin'
First of all you should NEVER cover ANY plant with plastic to protect it from the cold. You should use cloth instead.
As to how cold you plants can stand it depends a lot on the variety and how well developed they are. Most "early" varieties can stand temperatures into the 40s but for small plants the cold shock can really stunt them (it takes a long time for them to catch up to plants that are planted when it is "safe" -- temperatures into the 50s at night).
There are some varieties that have been developed to withstand cold (but not frost or freezing). Some of those varieties are Glacier, Oregon Spring V, Manitoba, and Siberian. Seeds for those varieties can be obtained from several vendors.
I live in central ILL and I went ahead and planted mine already. I took a gallon milk jug and cut the bottom out of it and put the jug over the plants and also on the big bertha pepper plants to protect them and mounded dirt around the bottom of the jugs. I am able to get almost a month jump on them. I never had a problem with them yet, been doing it for years.
I'm located in a SW Chicago burb and put my 1 - 2 week old seedlings outside in a coldframe consisting of 4 mil plastic, PVC tubing and dyed water bottles (to control temp flux at night). In years past, the little guys have survived lows into the mid 20's, but I do toss a blanket over the cold frame at night to help out. Haven't lost any to frost doing it this way, but do have indoor ones just in case. So far they have been outside two weeks are are small, but stocky.
I have an uncle in the Kalamazoo (MI) area that plants on Good Friday, and yep he has lost tomato plants over the years. He has saved some though by putting a sprinkler on at night and letting an ice shield form over the tomato plants. I have no idea how that would save them, but it does LOL.
Long story short, lows in the 40's is fine. Lows in the 30's, yah better protect them - even a 5 gallon bucket may do the trick overnight.
Good luck!
Hi Bill, If the plastic is only on the plants overnight and only a few times, is that material still a problem? What is the downside of using plastic vs. cloth? The plastic does not totally cover the plants over this short period of time. Can cloth do an adequate job of protection from the cold? We are expecting temperatures in the low 40's. My plants have been in a cold frame for 2 days and in the ground for a week. Are they sufficiently cold hardened to take those temperatures, or should I cover them for the overnight lows?
Sherw> sherw>
Sherwin,
Plastic can be a problem because it traps moisture and the moisture can freeze if the temperature gets cold enough. Cloth lets enough air flow through so that frost or freezing isn't a problem. When the temperatures are in the low 40s you can get frost. And you know how inaccurate the forecasters can be. The temperature can get lower in your area than what they predict.
If the temperatures are staying in the mid 40s at night you shouldn't have any problems using plastic. Just be sure to take it off in the morning. It can really get warm under the plastic when the sun comes up.
As long as the temperatures are getting below 50 I would continue to protect your plants. Others have mentioned using water jugs. I have used them in the past and they work very well. Just allow them to sit in the sun during the day. I have found that half gallon jugs work best. If you add dye to the water (red seems to work best) the jugs absorb heat better.
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