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Vegetable Gardening

Best veggies to grow in a cool greenhouse.

13 years ago

I have a greenhouse that remains above freezing in the coldest part of winter and average in the temperature ranges 50Ã¯Â¿Â½-65Ã¯Â¿Â½ through the winter. I would love to grow tomatoes and cucumbers in it but I realize it might be too cold for it. I hope I'm not limited to lettuce.

what would be the best suitable veggies to grow in these cool temperatures?

Bass

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Comments (11)

pnbrown
13 years ago
Way too cold for warm weather crops. What matters is soil temp especially.

Mustards and radishes are good for a cold greenhouse, and yes definitely lettuces.
glib
13 years ago
anything green, but also carrots, radish, turnips, beets, bunching onions.
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You're in the same zone as I am. I'm in central Saskatchewan and we normally have warmer summers than you, but this year it has been very cold and rainy with no change in sight, June has been 3 degrees C below normal. The watermelon and butternut squash will do better in the greenhouse. That's a given. The herbs will likely do better outside, especially if you have cool-season herbs (which most herbs are, except basil). Things like dill, cilantro, chives, chervil, rosemary, sage, etc. should be outside and they can tolerate some frost. Only basil needs to be started indoors. The tomatoes, corn and zucchini could go either way. They like it warm but not hot. I would keep some inside and some outside, so that no matter how the summer turns out this year, you have something. Corn takes up a lot of space so I would put it all outside. This post was edited by Slimy_Okra on Tue, Jun 24, 14 at 11:58
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Busy1, So, you're saying they want green tomatoes for frying or making chow chow or something? For a market grower, you know, that's good news.....because you can take green tomatoes to market earlier and (with green tomatoes being more rare) command a higher price. Sounds like a win-win situation. I just won't hardly pick a tomato green except in the fall. If a huge cold front is coming and I know I need to pick all the fruit, I'll pick the green ones and try to ripen them slowly, especially the longkeepers. Most years when I have a lot of greenies, I do send a big bunch to work with DH for one of his coworkers who likes to fry 'em green and also make chow chow. I do grow some green-when-ripe types most years, but they're no more suitable for frying when ripe than the ripe red ones are. River, Bill P., who used to post on Garden Web as Gone Fishin' before he passed away last year, raised most or all of his seedlings in a cold frame every year in either zone 7B or 8A. He was slightly east of Dallas in the suburbs, so I'm not sure which zone he was in but it was either 7B or 8A. He had great success. Actually, if I remember correctly, his was actually a hotbed because he put down a layer of hot (fresh, uncomposted) horse manure several inches down deep in a trench, put garden soil on top of that, and planted directly in the garden soil. The heat created by the horse manure as it decomposed kept his plants just warm enough at night. He always raised beautiful seedlings and the only trouble I ever remember him having was the year it rained non-stop and his in-the-ground plants almost drowned. So, I think it could work for you and, you know, you could throw a heavy blanket or comforter over the "hothouse" if a late snowstorm threatened. I suspect this is one of those projects that you'll just have to try to see if it works. It should work. People have raised seedlings using similar methods for years. If the seeds don't get warm enough to sprout, then you'd essentially be wintersowing, which ought to work fine anyway for most plants. Well, I'm not sure about peppers. Peppers don't like cold at any stage of their development, so I am a little concerned about that. I'd post a message for Seedmama here on this forum and ask her if she wintersows peppers and has success with them. I think Ilene wasn't happy with wintersown peppers in the past either, but I'm not sure if my memory is correct. (The older I get, the less confident I am that the things I "remember" actually happened.....LOL). You also could buy a seed germination mat and start seeds indoors using it underneath the flat. In the room where I have my light shelf (with ordinary fluorescent lights) and germination mat, the room always seems hotter to me than any other room in the house, and I think the lights generate more heat than you'd think. Just lights and a germination mat might create enough heat in your house to start seeds, and then you wouldn't have to worry about the temperatures dropping too much outside and causing you to lose your plants. If you try this method outdoors, you also could place milk jugs or two-liter bottles full of water inside your frame. They'd serve as solar collectors--absorbing sunlight and heat all day long and then releasing it into the air at night as they cooled. If you paint the bottle black, they'd probably heat up a few more degrees. You also could add heat by purchasing a soil heating cable and running it through the soil underneath the cans with your seedlings. You also could line your coldframe with a light-reflecting mylar paper. It would reflect light/heat back onto your plants. That kind of thing would be available in rolls from someone like Worm's Way that sells to indoor and greenhouse growers. You probably could get a similar effect from aluminum foil, but it might not be as reflective. Later in spring, as the occasional very warm day hits, you'll have to open the lid up during the day so that your plants don't roast. Dawn
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franktank232
13 years ago
Don't forget sun. Its so weak and doesn't shine for very long during Dec/Jan/Feb..i know that from my Eliot Coleman book, he shuts down production during winter. I think if anything you could overwinter crops (cool season) and they would take off in mid/late Feb.

Now if you had a heat source and some high powered lights, you could keep going...or u could just buy a place in Miami :) and grow mangoes.
ljpother
13 years ago
The average temperatures don't mean a lot if the lows are well below freezing. Don't forget cooling during the day.
jrslick (North Central Kansas, Zone 5B)
13 years ago
Due to your low light levels, plants that stay alive through winter, will continue to grow, just a a reduced rate. The trick is to get your plants to the almost mature size and then just harvest them as needed all winter long. It is called "Winter Harvest" not "Winter Growing".

What grows well in the late fall/winter? Spinach, Lettuce, Kale, Arugula, Beets, Carrots, Broccoli, Bok Choy, Mizuna, Tatsoi, Green Onions and Turnips particularly Haikuri Turnips, Radishes, Napa Cabbage and Cauliflower.

I currently have all of these crops growing in my garden. They are doing well inside my high tunnels with row cover. Although, it got to 72 degrees today, I don't think I needed the row cover!

Jay
Dan _Staley (5b Sunset 2B AHS 7)
13 years ago
As Jay has noted, light is important. I have a coldframe and low tunnels that go throughout the winter, although I have more light than most areas in the country. I have cabbage, spinach, corn salad (machÃÂ©), two lettuces, arugula going right now, and coldframe and a new low tunnel going in this week, with mizuna, lettuce, spinach, arugula, radish, cabbage going in them. You can help with the light with white reflecting surfaces, but not much. I cannot overemphasize how much arugula and mizuna help winter greens. And I'll have some of those Hakurei turnips going next fall, too.

Anyway, cool seasons only with info in OP.

Dan
jrslick (North Central Kansas, Zone 5B)
13 years ago
Dan,

Don't wait til next fall to try the Hakurei Turnips. They are really good. I didn't know I liked turnips until I tried them. They sold really well after people tried them and found out how great they are.

Jay
curt_grow
13 years ago
Jay thanks for the heads up on the Hakurei Turnips I just researched them. It is past planting date for my high tunnel. The soil temperature was down to 48 F. yesterday. So I will be planting for an early spring crop. They are high on the new crops list. Have you prepared the greens? ;)

Curt
jrslick (North Central Kansas, Zone 5B)
13 years ago
If you had the seeds, I bet you could try to grow them. They would grow really slow, but maybe it would work. I planted some several weeks ago and I am planning on planting some more this weekend. Just to see what happens.

I haven't prepared the greens. I really don't care for turnip greens. However, I have ate so many of these turnips, I can't count. I usually pull several and eat it like an apple when I am out in the garden. Now that carrots are ready, I have been eating those too!

Jay
Dan _Staley (5b Sunset 2B AHS 7)
13 years ago
Jay, 'Hakurei' came up on this board recently (maybe you), and I have them bookmarked for my next order at Johnny's, which who knows when that will be, but they're on the list. Thanks!

Speaking of Johnny's, they have a soil warming film there that Curt might be able to use, as long as the soil is isolated from the rest of the ground.

Dan
DrHorticulture_
13 years ago
Lots of good advice above.

In Saskatchewan, in my unheated greenhouse, I planted turnips, radishes, kale and bok choy in the 15th to 20th of September time period, right after the first frost took out the eggplant crop. Double row covers plus plastic went on in mid-Oct. Bok choy and kale were ready for harvest by late Oct. Some are still out there for continued harvest through November. Radishes are also ready now. Turnips are undersized but it's Saskatchewan after all! Soil outside is starting to freeze up but is still holding in mid-40s inside.
I won't let any for winter harvest, except some experimental kale to see if it returns in spring. A Maine winter is a piece of cake compared to Dec/Jan/Feb here. Also, don't let anyone convince you that SK winters are sunny. Four hours of watery sun every other day doesn't do it for me.

Signed,
Fed up of gardening in SK but still liking the challenge!

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