Cold Winter Greenhouses

Deep winter greenhouses and how they can work to produce food on the North Shore are discussed on this program hosted by Diane Booth, Cook County Extension. Guests in the studio include Melinda Spinler, who grows vegetables for a CSA in Cook County and Karina Roth, who manages the plant sale at Great Expectations School.  Liz Perkus, a U of M graudate student who is doing research on deep winter greenhouses, joins the conversation as well.
Correction: Towards the end of the program, we chat about nitrate accumulation in leafy greens.  Liz misspoke, and would like to correct herself.  Nitrates actually accumulate in plants during dark hours, so harvesting near sundown of a sunny day is best rather than morning.  Another way to reduce nitrates is to use compost-based fertilizer rather than simple, soluble fertilizers, and be careful not to over fertilize.  Leafy greens tend to take up more nitrogen than they need, so if there is a lot of extra nitrogen in the soil they can accumulate more.  A great article on nitrate accumulation in greens can be found here: 
http://www.mofga.org/Publications/MaineOrganicFarmerGardener/