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.
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
If the plastic is only on the plants overnight and only a few times, is
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.
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
Bill R wrote:
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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