What is your critical low temp. for covering tomatoes?

[blokesmom]

My rule of thumb is to cover plants if the temp. is expected to be below 50 degrees F. I have heard that some growers do not cover plants until it gets below 40, and still others claim they do not cover unless there is a frost.

What do you consider to be your critical low temperature before you cover your plants?

[TightenUp]

frost warning

[jmsieglaff]

Mine live in a cold frame until it is time to plant out. After planting, if I think the nighttime temp will fall below 38F I will cover. (I don't have too many plants.) I use that number because there is the possibility of frost, especially if the temperature drops a couple degrees more than expected.

We are expected to have a rather cool night this coming Saturday night for the very end of May (around 40F), but the plants will be fine and I will not cover.

[PA_Julia]

I will cover when the forecasted low is 36F or below due to the increased chances of patchy frost occurring otherwise I don't do a thing.

[carolyn137]

No single temperature for me b/c even if a frost warning is out it depends on elevation, winds and humidity as to whether there will be frost.

Last week there were frost warnings three night in a row and while those in the village below me did get frost, and it was 33 F one morning here, I got no frost b/c of elevation.

But then I wouldn't have any plants planted yet since AVERAGE last frost here is May 15th and I'm old enough to see a wicked blizzard here the end of may. So no plants go out until the first week of June, weather permitting.

I see you are in W MA, can't be that far from me and I'm on the NY/VT border about an hour N of Albany and to get to W MA is an easy trip.

Carolyn

[KarenO]

Frost warning. Does not mean there will be frost. 50 degrees is a fairly reasonable nighttime temp here in the spring. I look forward to 50 degree nights
Karen

[bughunter99]

Anything under 40 degrees if clear skies are forecast.
Anything under 35 degrees if cloudy skies are forecast.

Anything extremely tropical , such as tropical orchids etc comes in if temps will be below 50 degrees, I don't mess with covering those.

[Stvrob]

There is no compelling reason I can think of to cover tomatoes if the night is only expected to fall to 50.

[SueCT]

Below 40 degrees.

[Lindalana]

As Carolyn says, circumstances more than just temps- wind, how low, for how long, how moist, what is daytime temp etc. Overall I use WOW for my tomatoes- helps with this cover/ uncover thing.

[joseph]

I don't cover tomatoes... However, unless I am doing a frost tolerance trail, I don't put them out into the field until I feel like night-time temperatures will be above 40F for the rest of the summer. In my garden, a clear night after a rainstorm, and 40F air temperature will freeze the leaves of some varieties due to radiant cooling. I'm as content as can be if about 10% of the plants get frozen each year. I love that the most frost sensitive plants get eliminated from the genepool. Sure, there's a bit of randomness about frost, but it's also clear to me that there are family groups that survive frost or cold weather much better than other families.

[AlittleSalt]

What I have read is that frost can occur at 42F.. A few years ago, here in Texas - a lot of people lost their tomato plants on May 2, because of cold temps.

As one tomato gardener to another - If you think it's too cold - cover them. There's a million ways to do so.

[BlackBear]

Early Spring Frost Cover Dance :

I look at the 10 day forecast in early spring and make the trend and cut it close at 2 C or 3 C for the low . (only if the average of the Low and High is 6C or better in 10 day trend so a trend of 4 C Low/ 6 C high would not be worth it to start the early spring cover dance. but 2 C/ 10 C would be worth it .)

This is for the best guestimate. For outdoor my containers that are wind protected . Many times in the last gasp of cool spring one can get good healthy outdoor growth with the cool climate varieties(In a cool climate) and only have to scramble and cover once or twice in 10 days. then one is good to go. I often can get an extra month of cool growth and good root development in protected containers prepping for the main growth season .

Many disagree with this and I think even the California growers rate under 9 C as
mark of not healthy for Tomatoes. I would hardly have Tomatoes outside here if I waited for my area to be the "California Growers ideal ".

First Frost is not really the issue as such here as I must move the select containers into a fall "dry area " to finish off ...the problem is protecting the plants with Cover from the cold fall rains which can come in late August.

[Gardeneer]

Once our LFD is behind us, there is very very slight chance to get frost. But we continue to get lows in mid 30s til early May. I started planting out as early as 4/8 this year. The lowest had been 36F and I have never covered anything. The lows stayed around in 40s til May.
Tomatoes can tolerate even 32F for a short duration. They are tougher than what some folks think.
This one fruited when lows were still in 40s.

[BlackBear]

My magic date to wait to put cool tolerant toms out is about May2,

and very rarely do I have to cover if it is the close temp of +2 C .

.....but admittedly this year most certainly could have started the last frost cover dance in mid April this year....I just use the may2 date here to combine with the photoperiod as well as frost considerations .