seedling in an unheated greenhouse

glazed(5b)February 18, 2009

I have built a small 8 x 8 unheated greenhouse and was wanting to put some of my seedlings inside. I am going to be growing all the basic veggies and flowers but I have also started some celeriac and jicama and I am wondering when to put them in the greenhouse. I was thinking that the onions, broccoli, napa cabbage, pansies could go inside the greenhouse now, also when can I put the marigolds, peppers etc out? I have never used a greenhouse before so needless to say I am very excited but don't want to get to eager an mess it all up. Any info would be helpful and most appreciated. Thank you and sorry if this is not the right place to post this message, I really couldn't find a forum that best described what I was trying to do. One other note, I start all my seedlings in the individual peat pellets that I swear by. Thanks again.

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The greenhouse is unheated so you will have to know at what outside temperature the greenhouse will stay above freezing. On a windy night, the greenhouse will lose heat faster. I have an unheated sunroom attached to the house. I determined I have about a 12-15 degree buffer from the outside temp in the spring.

As to when to put plants in there will depend somewhat on the temperature the greenhouse can maintain at night. While most will tolerate cold temps, the warm season crops, like tomato, won't like it. I would wait on warm season crops until the greenhouse can maintain temperatures above 45 or so at night.

Make sure to be able to vent on a sunny day. Overheating can also damage the plants. Our closed, unused greenhouses at work are already getting into the 90's on sunny days.

Vent on cloudy days if the greenhouse feels very humid, the plant foliage is wet or there is a lot of condensation or dripping.

    Bookmark   February 21, 2009 at 12:12PM
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Thank you for the info. So as long as the greenhouse temp stays above 32degrees my cole crops will be fine?

    Bookmark   February 25, 2009 at 2:49AM
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If you are in a real hurry, you can add a litttle heat for those crispy nights by making up a string of light bulbs (4 bulbs at 60 watts ea.) One in each corner area will help keep the temps up. Another idea is to purchase a heat cable (used to keep the ice from building up on the roof of the house). Just run it around the inside base of the greenhose and plug it in at night. You may want to consider purchasing a "Max/Min" thermometer which will indicate the low temps you're getting overnight inside the greenhouse. Very useful !! Good Luck.

    Bookmark   March 21, 2009 at 4:23PM
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A heating cable..nice idea. Yesterday(Apr.19th) featured an uncommonly strong east wind which toppled my tiny greenhouse. Actually ,other than losing a small favourite pot the damage was minimal although I now know I need a better barrier for those unexpected gales. R squared

    Bookmark   April 21, 2009 at 5:48AM
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