Last year I tested several different varieties of lettuce, plus a few other greens, to try and determine just how much cold weather they can take. I grew the lettuce and greens in my cold frames, which were covered with spunbonded polyester row cover fabric (like Reemay or Agribon). If you are interested in my cold frames, you can read about how I make them here.
The light row cover material works here in Southern Indiana because we rarely get a large amount of snow at one time. The material keeps out wind, and provides some protection against the cold. It also provides protection against deer, which are a real problem here in our garden in every season.
The results of last year’s trial were very encouraging. The lettuces that did well included Oak Leaf, Sea of Red, Radichetta, Winter Density, Ruby and Spotted Trout (aka Forellenschluse and Freckles). The tested greens all did well (Arugula, Komatsuna, Yukina Savoy and several varieties of Spinach). The survivors all endured repeated freezing and thawing cycles, and several periods of below freezing temperatures that lasted for days.
Last year the varieties I planted were limited to what seeds I had on hand for fall and winter planting. This year I planned ahead when ordering seeds, and I have included some varieties I selected specifically for their reported cold hardiness.
And this year I have more cold frames to devote to the testing. Soil preparation included adding about a one inch layer of compost to each bed, plus some slow release organic fertilizer (5-3-3). I tested the pH and it was fine, so no lime was needed. The spinach was direct seeded, all others were transplants that were started inside under lights and then grown on in the greenhouse and outside. The seedlings were all about 3-4 weeks old when planted.
The spinach was all planted in one cold frame. I have the hybrid variety Space, and the open pollinated heirloom varieties Giant Winter (Gigante Inverno) and Viroflay. Seeding was done on 9/5 and 10/3. Spinach generally survives our winters with a little protection, so I am really interested in seeing which varieties perform best here. I was able to start harvesting some of the leaves in early November.
The second cold frame (#2) is planted all in lettuces: Winter Density, Black Seeded Simpson, Flashy Trout Back, Radichetta, Kweik and Merlot. Flashy Trout Back is a Frank Morton selection of Forellenschluse with more uniform red splotches on the leaves. Kweik is a butter head with cold tolerance suited for tunnels and unheated greenhouse production. The lettuces were all planted in mid October (10/17).
The third cold frame (#3) is a mix of Asian greens and arugula. I planted Ice Bred and Even’ Star Winter arugula, plus Mei Qing and Ching Chiang pac choi, along with Komatsuna and Yukina Savoy tatsoi. The Komatsuna is an open pollinated variety I got from Nichols Garden Nursery. Ching Chiang is a green stem pac choi supposedly with heat and cold tolerance. I will compare it to my old standby Mei Qinq, which does well in all seasons here. I will likely harvest both of the pac chois when large enough to use and then replant those spots with some Mizuna seedlings I have growing. This cold frame was planted on 10/25.
The fourth cold frame was just planted recently (11/19), and is mostly lettuces with a little tatsoi. The lettuces are Oak Leaf, Spotted Trout, Winter Wunderland, Hyper Red Rumple Waved, De Morges Braun, Rouge D’Hiver, and Ruby. The tatsoi is Even’ Star Tender Tat, which is actually a mustard and tatsoi cross that is supposed to grow more upright than tatsoi and be very winter hardy.
I also have a small cold frame (not homemade) that I planted with some Senposai seedlings. Senposai is a cross of Komatsuna and regular cabbage. I grew it this year in spring and summer and it was very promising. It has large green leaves with a mild cabbage flavor. It will be interesting to see if it can survive the winter here.
I will report back on these trials in the weeks and months to come, and share the results. My main goal of course is to keep us supplied in greens all winter long, while testing the performance of different varieties. And of course I love to experiment!