What results did you have growing greens in an unheated hoop house in Iowa from Winter 2012-13, when it was a bit cooler than the Winter 2011-12. Thanks!

First, I'd like to apologize for hijacking this thread, but I thought my question would be relevant to this conversation. I'm new to growing/gardening and wanted to start a 16' x 20' greenhouse in our backyard here in DSM. I wanted to get your opinion on how things will grow if I decide not to trench below the frost line in Iowa. Will my plants be okay throughout winter if I just add a few inches of top soil on top of the ground and encompass the area with pvc/screen (as a greenhouse)? I'll be mostly growing peppers, mints, some asian herbs, lettuce, tomatoes, and hopefully cucumbers/pumpkin.

I'd like to get some of your opinion on this. Thank you.

I too want to build a greenhouse in the next couple of years here in Iowa. Still trying to get the pros and cons. I have looked at pit or walapini style greenhouses, Solar greenhouses with a heat pit beneath the plant beds and the use of rocket mass heater for days without sun. Also looking at an attached greenhouse to my home. If anyone has had any experience with any type of greenhouse, I would welcome your information. I want to research it well before I build it. I would like fresh vegetables year round as I am a vegetarian.

Pls keep posting what you're learning. I too am in Des Moines and am hoping to rework my not-yet-heated-but-has-one-layer-of-windows south porch as a greenhouse, with maybe minimal heat (something that keeps it from freezing but stops heating when it hits 40 degrees, perhaps). Thanks!

I'm curious what will grow at 40 degrees in Iowa in the winter? Doesn't the ground need to be warmer than 40 degrees? Isn't that why it's so hard to get anything growing in April in an open garden spot? My garden is in full sun and I've never had anything grow until the soil got warm, not even by using black plastic around the plant/seed.