winter garden in greenhouse?

[Hanako]

I live in northern Michigan in the upper part of the lower peninsula.
The growing season starts in the end of May, ends in September or October. For cool weather stuff you can start in mid to late April until the main gardening season (end of May) starts (if the weather cooperates). Gardening zone is 5a.

I'm wondering if it would be possible to grow crops in a greenhouse throughout the winter. I DO NOT mean overwintering, where you put seeds in the pots in the winter and create 'mini greenhouses' (basically putting them under some sort of incubation device) then just wait for them to germinate in spring when the weather warms up.

I mean actually starting from seed in the greenhouse in winter, and harvesting throughout winter. This would be for cool weather stuff.

I would just be basically putting containers in the greenhouse, because that's the method of gardening I use, and sowing my seeds in them.

If so, how would you go about doing it? Would the greenhouse have to be heated, or would this not be necessary, because of the glass absorbing heat from the sun, thus creating an incubator as a result?

I honestly don't know, never grown stuff in a greenhouse before, so could really use advice with this.

 

[lesa]

Unless you are going to heat it- your stuff will freeze, after prolonged cold spells... You should be alright with spinach and greens, but anything delicate is going to freeze. I am hoping to have things growing in mine, until end of December and then start again, in March... we'll see what mother nature has in mind!!

 

[digitS']

Hanako, with the angle of the winter sun - it is not possible to gain a whole lot of heat during the short days of winter. Yes, a clear sky will allow the greenhouse to heat up; maybe even requiring ventilation on a sub-freezing day. But, then come the long hours of darkness.

Imagine a cloudy day of 25F with wind. There isn't adequate sunlight to raise the daytime temperature inside the greenhouse above freezing. Then, night falls again. If weather like that continues through 5 or 10 or 20 days, everything inside will be frozen throughout all of that time.

Very few plants make any growth at all when the temperature consistently falls below 40 overnight. Something that may produce a crop in 45 days outdoors during the growing season may easily take twice as long under those cool conditions.

Heating a greenhouse is expensive unless you have some additional insulation during the hours of darkness.

. . . just my 2 and I'm sorry that it is fairly negative. To take a slightly different twist on the idea: read Four Seasons Harvest by Eliot Coleman. He isn't talking so much about winter-sowing for spring crops or about winter production. Rather, the book is about growing vegetables during the fall, for harvesting through the winter.

Steve

 

[Hanako]

Some questions regarding what you said. If the greenhouse were properly insulated, then would it be possible to grow (from seed) in the winter (and throughout) or would it just be too cold? How do you go about insulating a greenhouse?

If it's not possible to do a winter garden in the greenhouse in northern Michigan, if it were in a warmer zone, then would this idea be feasible?

The other question I have is people are saying it needs proper heating as well.

Last but not least the veggies I plan to grow are cold weather stuff. However I know some cold weather veggies are more hardy then other ones. What temperature range can 'hardy' cold weather veggies survive through? By 'survive' I mean being able to take those temperature ranges and come out of it alive and healthy; not just surviving it but then struggling to stay alive and/or dying.

Below is the list of veggies I'd like to grow. They'd be done in containers, because that's the method of gardening I use, is container gardening.

carrots, kohlrabi, beets, turnips, cabbage, broccoli,
mustard greens, kale, collards, daikon (asian radish), red radish, swiss chard

 

[catjac1975]

A free standing green house will not stay warm enough to grow crops. The best you can do is lengthen your growing season at both ends of the season. I plant in the ground in a tunnel greenhouse and get some early crops. I can get a few extra weeks into the fall providing the temp doesn't drop too low. A low tunnel might stay warmer longer-but I think adding heat would cost a lot. Professionals certainly do add heat but for a homeowner I doubt it would be cost effective. I have read about using a 100 watt light bulb in a low, small tunnel.

I also have an attached greenhouse which has a lot of insulation on all sides but the glass side. Heat is added from the house. I use it to start seedlings. I have grown tomatoes for several winters with luck. I will not this year. It was not for more than just fun-is not cost effective. Fun to have a few tomatoes when the snow is on the ground. You need greenhouse tomato seed. They are not as good as garden grown. I will stop this year because I am organic and the white fly were a hideous infestation. I have also grown lettuce with success. Have fun
Cathy

 

[buckabucka]

I see this post is old, but we are trying winter gardening in an unheard greenhouse here in Maine. this is our first year trying this, things like spinach, arugula, carrots, etc.
You need to get Eliot Coleman's book, I think it is called Winter Harvest. you need to double cover crops (cover them with floating row covers inside the greenhouse), and things will grow very slowly due to light levels.
It's worth experimenting, I think.
Have fun!

 

[digitS']

. . : read Four Seasons Harvest by Eliot Coleman. He isn't talking so much about winter-sowing for spring crops or about winter production. Rather, the book is about growing vegetables during the fall, for harvesting through the winter.

Steve

Right you are, Buckabucka.

Steve

 

[buckabucka]

. . : read Four Seasons Harvest by Eliot Coleman. He isn't talking so much about winter-sowing for spring crops or about winter production. Rather, the book is about growing vegetables during the fall, for harvesting through the winter.

Steve

Right you are, Buckabucka.

Steve

Ha! I obviously overlooked this part of your post, as I was skimming while rushing off to work. I will be very interested to see what this winter brings, as this is our first year with a hoop house. I can say that it was great for growing eggplant and sweet potatoes this summer.
Right now though, our greens harvest has been limited by moles, mountains of slugs, some hefty caterpillars, and perhaps some other rodents.