Hate to loose a crop, don't you? I believe lettuces can't stand the freezing like some other greens because of the high moisture content. The kale may be too young to have built up resistance to the rather extreme temps you described. How old are they? Last year, my red russian kale shrugged off a couple of 15 deg morns here in north GA but continued to feed us from late fall until early spring without a hoophouse made from fabric row covers and #9 wire arches. If I were to put it on one thing, I'd say it was the low temps that did them in. What kind of hoophouse do you have?

Hello,
Is your hoop house 1 single layer of plastic?
Have you tried bottles of water for heat conservation?

If you place gallon milk jugs full of water throughout your cold frame they will heat up during the day, and slowly release heat throughout the night.

Also, the romaine lettuce Winter Density is more cold hardy then other lettuces. Most likely due to the thickness of the plant cell walls. You can find this variety at a lot of seed companies. I know Territorial, and Johnny's carries it.
Happy Holidays,
David Burton

Thank you both, gentlemen, for your input.

These were all fairly young plants, 2-3 months old that I grew specifically for the fall/winter/spring season in the hoop house. It's just a plain Quonset hut shape, 12' x 24' and 7' tall at the center. It has a Dutch door at the front and a 2'x 3' "window" in the back for ventilation that I can close or open as needed. It isn't very weather tight but will get pleasantly warm even on the coldest but sunny day. I got the hoops and lumber for the foundation in a trade with a friend who wanted something a little more elegant. We used plywood for the ends and bought the cover material from Northern Greenhouse Sales. I did find a mature volunteer plant, I think a Brun d'Hiver, that is doing fine. I planted Winter Density--still have a partial package in storage--but my old computer crashed taking my records with it. I will be very surprised if it were the cold alone because this is my eighth year using the hoop houses in equally cold weather without this result. Yes, the hoop house is only one layer of plastic. I have tried water in some 55 gal drums but it seemed to take up so much space without much change in the night time temps.

It is common for all the veggies and herbs to freeze completely overnight but as soon as the sun warms the space, they have thawed and been beautiful. You would never have known they were even frozen at all. Since the wind and sun can't damage the plants while they are frozen, they perk right up once the temperature inside rises above 32o.

I keep forgetting to take a magnifier out to get a very close up view of these plants. I noticed today that the "Tango" lettuce seems to be putting out fresh growth from the center. The other varieties are Black seeded Simpson, Forellenschluss, Red Romaine, Rouge d'Hiver and the Siberian kale. I'll post back if any of the plants recover.

Thanks again. And, you can bet I hate to lose a crop. I've read both your "My Pages" and your farms sound neat.

You have more years of experience than me on this! When I have a problem, I start with the basics - air temp, soil temp, humidity, ect., and go on to diseases from there. I have a Radio Shack max/min thermometer that has a remote probe that I place out side the hoophouse while the unit stays inside to get accurate info on what happened. Too late this time but for $25 it could answer some basic questions.
Get Elliot Coleman's book Four Season Gardening, too.

I do have a copy of Eliot Coleman's book. It and Greenhouse Gardener's Companion by Shane Smith are my main sources of guidance for this project. I finally got out of my own driveway last Wednesday and checked out every book from the library that I thought might be even marginally helpful for this problem. I've been on the internet sites about it too, not just questioning other gardeners.

I've looked at the max/min thermometers but never got around to actually buying one. I do have a thermometer that registers temperature and humidity. I open and close the window and top half of a Dutch door as needed rather than having an automatic opener. It's really a low budget enterprise. Unfortunately, a lady who used to buy my greens from a natural food outlet in town called me last week wanting to know if I had any extra for sale privately. Another kick in the head!

Coleman's Winter Harvest Manual may be of additional help. I think it is available through Growing for Market.
He specifically uses row cover inside the greenhouse for an additional layer, to modify temps even further. He also gives varieties and times for planting to get winter harvests. Better adjust for your area.
Ann

Oops, I forgot to mention that one, Ann. I have it too.

I was just in the hoop house with a magnifier AND my reading glasses. Several of the plants I checked are putting out fresh growth from the crowns so maybe not all is lost. The kale is definitely toast.

Thanks again, everybody.

My kale--Winterbor--is still going strong in the open garden covered only with a doubled row cover. We've had temps below +10.

I think that you will get a huge flush of growth from the lettuces, though it will be very slow until the days lengthen considerably--early Feb, at least. Clean up the dead foliage, perhaps put a row cover on, and see what happens.

Hope this is not too tardy a post. Mogardener, did your lettuce make a come back ? If so, was it Winter Density or other(s) ?

Your Kale did not come back ? I always thought Kale was much more hardy than lettuce.

Have you already started your overwinter garden for the hoop house for '07 / '08 ?

Q # 4 - Did you use FRC inside the hoop house or are you going to this year ?

As long as the forum folks post follow-ups, I'll answer.

No, the lettuce died. I have used Winter Density in the past but don't think I had used it last fall. In one of my later responses, I listed the varieties I could remember.

The kale did come back, went to seed this spring and I have some volunteers in the hoop house right now.

I'm in central Missouri and we have been under terrible heat/drought conditions since Independence Day, our last real rain. I barely managed to stay outside long enough to tend animals so haven't really had a chance to do much to the hoop house except put more compost on the beds that didn't get it last fall. Nothing planted as yet but it's on my to do list for this weekend.

I have used FRC in the past with good results. I had the hoops all set up to support FRC over the beds but hadn't yet put it in place because our fall was unseasonably warm. The snow storm that zapped everything came in very quickly and I had other jobs to perform in case we lost power. Then after it did strike, we had so much snow, I couldn't get to that hoop house for 2 days until DH could clear the drifts with our tractor.

I have my fingers crossed that things will go better this season! Thanks for asking.

Thank you MO. Gardener

Are you sure this year wasn't much colder than any previous? On February 10th it got down to 15 below zero here and about 15 inches of snow. The next night it was 5 below, then the next night it was zero. The last time we had weather that cold, was 1977.

This storm may have actually frozen the roots.