Growing Spinach in the greenhouse?

brandond(6)December 1, 2011

Hey everyone. I'm growing spinach in my greenhouse. Im in the early phases of growing spinach. I have two flats of seed that has germainated and is around 4 inches tall. I have been running my fluorescent lights 24-7 just above the flats. I plan on transplanting the spinach to a 20x36 in container. I have some granite thats one inch thick. I have a heating mat that is specific for germinated seeds. If I were to take the heating mat and place it down first, then lay the granite on top of it,followed by the container filled with a grow mix and the spinach, would this work? In terms of plants, I have around 40 plants. My theory is the granite holds heat very well. I wouldnt haven to heat the air in the greenhouse either. I thought about trying 50 degrees with the heat mat and seeing what that does. THis should be enough spinach for myself and my wife this winter. If anyone has tried this or has advice please let me know. I also bought some shultz liquid fertilizer to spray the plants occasionly. thanks

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jrslick (North Central Kansas, Zone 5B)

Save your money and effort. Just plant the spinach. It will be fine. Spinach is a very hardy plant. Inside a greenhouse, it will over-winter just fine. I don't know where you live, that would be nice to know. We have had lows in the upper teens already this year and the spinach has never tasted better. This is my 4th year of overwintering produce.

I have over 800 square feet of Spinach in one of my high tunnels. I will harvest it and let it grow all winter long. These were taken several weeks ago. Just don't look at the weeds!

Another problem with the heat may actually get it too hot and cause it to bolt.


    Bookmark   December 1, 2011 at 11:18AM
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I live in zone 6, close to Springfield,MO. So I dont need fluorescent lights to promote growth. My greenhouse is small 10x10. It is insulated though and I use the heavy duty swimming pool cover material as insulation. I actually did plan on just making some raised beds in long planter boxes inside. So when should I transplant the spinach to the beds. Its around 10 days old right now. Should I heat the house at all? Any tips or knowledge would be helpful. thanks

    Bookmark   December 1, 2011 at 11:58AM
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jrslick (North Central Kansas, Zone 5B)

To be perfectly honest, your spinach should have been planted in October in order to harvest during the winter. When the sun is out less than 10 hours a day, plants don't grow a lot. They grow some, just at a reduced rate. You can help your plants along by having the lights come on in the late afternoon/early evening and have them run for a few more hours. That would help with growth. If you want to be able to harvest this spinach in the next 30-45 days, you may have to add a little heat and more light.

Check out the link below. It is about growing spinach in a high tunnel. This trial was conducted near Kansas City.


Here is a link that might be useful: High tunnels and spinach planting dates

    Bookmark   December 1, 2011 at 12:19PM
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poppa(z5 MA)

I'm with Jay... save your money.

Yes, the spinnach will slow but you just plant enough to give you the amount you want. Off a dozen plants I was harvesting once a week.

The best part is, I think Jay is right that winter grown spinnach is the BEST tasting! Very sweet and none of the bitterness!

    Bookmark   December 1, 2011 at 9:08PM
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