What Temperature to Cover Tomatoes at Night?

I moved to central Texas a while back, from Hawaii, so gardening in a place with seasons is new to me. Also, the weather here is notoriously erratic, perhaps the last few years more than ever. We had a brutal, hot, dry summer, with very little spring weather (went from cold to hot really fast), and we didn't get much produce at all from the garden. Not compared to what I planted, anyway.

The temperatures have been more mild for the last 6 weeks or so, and my tomatoes are finally happy. Some fruit ripening, lots and lots of green fruit, and flowers galore. However, we have a low nighttime temp of 39 forecast for Tuesday night, 44 for Wednesday, and then back up to mid-50s to mid-60s for the next few weeks, with daytime temps in the high 70s to high 80s. So basically a cold-snap followed by pretty perfect gardening weather. This seems normal for here for the next month or two. Even once we get a frost, we can get weeks more of warm temperatures. First average frost in my area is a month away, but it can come any time, or even, some years, not arrive until early January.

I'd like to keep my tomatoes going as long as I can, since we didn't get many in the spring or summer, and they are doing so great now. I do have some .55 oz row cover I can put on them, which I would take off during the day so they don't cook. At what temperature should I cover them? Just when it frosts? Or when the temps dip into the 40s, in order to try and keep them setting fruit? What is a good strategy? The coldest time of the night here is actually 7am, just when the sun is rising, so I think if I put the cover an hour or two before sunset, I'd have the best chance of holding in the heat of the day without cooking them.

I do have some smaller patches that I don't plan to cover, and I'm sure I'll learn a lot by comparing the two groups, but wondering what more experienced people have to say too.

You will probably be better off waiting for a reply from someone from your region.  If I cover tomatoes, I do it at sunset when the temp is supposed to drop below 35.   I am on a hill, and my garden is near a large pond.

I get radiant cooling at my place. That's occurs when the deep cold of space cools the plants when skies are clear. The radiant cooling effect is about 8 -10 degrees F in my high elevation garden, so I expect frost on clear nights when air temperature is around 42 F.

Fabric based floating row cover is intended to be left on day and night.

My general philosophy is to not fight the ecosystem. Doing so costs time and materials for marginal return.

Joseph, I'm so glad you responded. About 1/3 of the tomato plants in question are your "Brad" tomatoes that I got from the experimental seed network website. I started the seed a few months ago for my fall garden and they have just done awesome from day one. Deeper green and more vigorous than the other varieties I planted around the same time; just a joy to watch grow. They have lots of green fruits and are flowering like crazy. I'm very much looking forward to the first ripe fruits. Any insight on the cold tolerance of this particular variety?

I very much prefer to let nature take its course as well. Row covers never appealed to me until I moved here and saw how erratic the weather can be. There are some really swift temperature changes sometimes; New Years' Eve last year was 80 degrees and my kids were playing outside in shorts. That night, it dropped 50 degrees and the next day they were in their thick winter coats. That's hard on plants, so I did buy some row covers as a cushion to use in emergencies. And now that I have them, I'm thinking maybe I can use them to squeeze out some more tomatoes out of this year, since the summer was so bleak and unproductive.

Covering your tomatoes really helps save some plants; at least for a short time here in PA. Something else I've found that works well is bags of grass clippings, Even freshly cut clippings with or without a lot of leaves. Just place them between plants. Black plastic will absorb some additional heat above what the composting grass creates. And off course another option is bags of fresh manure. Once the tomato plants have frozen you can layer the manure or clippings into your compost pile to speed that up. You can also combine the bags of heat with the row covers.

When they predict freezing temps I pick all the tomatoes and store them in a cool spot. they used to say to individually wrap them in newspaper; but I've found  that's unneeded. I've kept tomatoes that ripened at Christmas.

Hi. Tomatoes do not like temperatures below 50 degrees at all. I'd cover them at night when the day starts to cool to retain heat and remove the cover the next morning only when the temperatures really start to warm up, like 65 or 70 or so. Tomatoes love heat. When temperatures start to cool here, I put all my peppers under a protection tent and leave it on even during the day. Peppers are similar to tomatoes as far as the temperatures they prefer. My peppers loved it and lasted well into November. I'd do the same with my tomatoes but they get way too big to cover :)
Another thing you can do to force the tomatoes you have to ripen is cut all the flowers and small fruit off of the plants. I did that the beginning of this month here. This will force the energy into the fruit that has the highest likelihood of maturing.
And, if you get a cold snap when you still have green fruit on the plants, you can cut them off and hang them upside down in the garage. Amazingly, the fruit continues to ripen. Plenty of people where I live serve fresh tomatoes at Christmas when they store their tomatoes like this.
Happy gardening!

Lila, welcome to Texas.  I was in Central Texas until I moved to the Hill Country.  Though I have pretty much lived in Texas since a teenager.

The weather is very unpredictable in most parts of Texas.

When we first moved to Texas, girls were wearing shorts at the local 7/11 convenience store in January and I was wearing a sweater.

Follow the advice of the others though you might be able to keep those tomato plants growing all year long.  I have had tomatoes in December by pulling them before a freeze and ripening them in a paper sack on my kitchen counter.

.

Anne Miller wrote:Lila, welcome to Texas.  I was in Central Texas until I moved to the Hill Country.  Though I have pretty much lived in Texas since a teenager.

The weather is very unpredictable in most parts of Texas.

When we first moved to Texas, girls were wearing shorts at the local 7/11 convenience store in January and I was wearing a sweater.

Follow the advice of the others though you might be able to keep those tomato plants growing all year long.  I have had tomatoes in December by pulling them before a freeze and ripening them in a paper sack on my kitchen counter.

.

Yes, it is definitely different here! In a way I love it, because just when you start getting tired of the cold in winter you'll get a warm day or week, but the temperature changes are also really hard on plants. I want to grow cool-weather crops like kale, collards, etc all winter long. This past winter, we had one occasion where temps were in the 70s and then abruptly dropped to a hard freeze, accompanied by strong winds. My poor little kale plants froze solid, which probably would have been fine, except that the wind whipped them around and pulverized them while still frozen. They were young and didn't have woody stems yet (started late that year) so I am wondering if more mature plants would have made it through that ok. But I decided to buy some row covers for occasions like that, just in case.

Thanks for the grow report. Brad is not frost tolerant, but it grows well in cool temperatures.

If you've got the fabric, you might as well use it.

Joseph Lofthouse wrote:Thanks for the grow report. Brad is not frost tolerant, but it grows well in cool temperatures.

If you've got the fabric, you might as well use it.

That's good to know. I wouldn't expect frost-tolerance, but I was thinking with your shorter season they might have some cold tolerance built in.

I got them started a bit late, but I should still get a good crop. They seem to be fruiting  on around the same schedule as the various cherry tomatoes I planted around the same time. They are such beautiful plants!  I just saw the first fruit starting to turn orangish this afternoon. I can't remember when I started the seeds, probably early August, and I think I planted them out in the beginning of September. Texas is different that way; most people let the majority of their spring garden die in the brutal mid-summer heat and then plant everything fresh again for their late summer/ fall garden.

Since I do have the row covers I'm kinda curious how long I can keep these plants going.

I haven't had any problem with tomatoes in Vermont until they are hit with frost. If early frost is predicted, I'll cover them for that night and remove it in the morning. I have kept tomatoes going for several weeks of Indian summer after first frosts.

Tomatoes don't thrive in cool temperatures, but they survive. On the other hand, any frost at all will kill them all in a single night, turning the entire plant to mush.

Microclimate effects will also determine whether and where you have frost. It's not just about forecast temperature.