DWGs in Minnesota can be used to grow cold-hardy crops that thrive with minimal light, providing year-round production capacity for small-scale farmers and gardeners. Crops well-suited to DWG production include a variety of lettuces, herbs, brassicas, Asian greens, and sprouts.
What is a deep winter greenhouse?
Deep winter greenhouses (DWG) are passive-solar greenhouses that use the energy from the sun as the primary source of heat.
DWGs are built in an east-west position, with a south-facing glazing wall that is steeply sloped to capture as much solar energy as possible on the coldest days of the year. The solar-heated air inside is drawn underground with a fan and stored in an insulated thermal mass of soil or rock where it is available to heat the space at night.
The University of Minnesota Extension, College of Design, CFANS, and Mechanical Engineering are partnering with five farmer partners throughout Greater Minnesota to build and test prototype farm-scale deep winter greenhouses:
- Owl Bluff Farm, Houston
- New Story Farm, Hutchinson
- Honeydew Farm, Park Rapids
- Tintah Beach Farm, Thief River Falls
- Chelsea Morning Farm, Two Harbors
These farms will build the farm-scale deep winter greenhouse prototype, grow winter crops, and work with the UMN on conducting research trials, outreach events, and winter production workshops.
Farm Scale Deep Winter Greenhouse 2.1 prototype
Request building documents
Resources
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Design and construction
- Farm scale deep winter greenhouse v 2.1 construction manual (document request form)This greenhouse design is intended for small- and mid-sized vegetable farms in northern cold climates. It is designed for simplicity of construction, energy efficiency, and is scaled for diversified vegetable operations growing for local market customers.
- Deep Winter Greenhouse v 2.2 construction manual(document request form)
The earlier deep winter greenhouse prototype (v2.2) is highly energy-efficient and smaller, but has a higher per-square-foot cost than the farm-scale deep winter greenhouse. This model is suitable for hobbyists and small farmers who do not face significant budget constraints.
Operation guides and manuals
- How to Operate Your Deep Winter Greenhouse
This document provides an overview of the basic features and essential operating principles of a deep winter greenhouse. The focus is on how best to utilize passive solar heating, manage environmental conditions, and preserve the longevity of the greenhouse structure. - Starting a DIY Deep Winter Greenhouse operation on a budget
For those who are looking to build a DWG on a budget, this report explains some of the techniques used by experienced DWG producers to build your own affordable structure for winter production. - Video: Design overview and lessons learned from a Farm Scale Winter Greenhouse in Minneapolis
UMN College of Design faculty member and designer Dan Handeen provides a tour of a Tamales y Bicicletas, a farm-scale deep winter greenhouse in Minneapolis. Handeen also reflects on design lessons learned during the development of the latest deep winter greenhouse design. - Buy the Northlands Winter Greenhouse Manual (2020)
Authors: Carol Ford, Chuck Waibel
Supported by RSDP, the Northlands Winter Greenhouse Manual provides detailed and easy-to-read construction specifications for building a DWG in northern climates as well as production techniques for successfully growing crops. - Cold Climate Greenhouse Resource Manual
This guidebook highlights the successes and lessons learned by growers across the Midwest who have designed and built cold-climate greenhouses to grow produce during the winter with minimal reliance on fossil fuel-based heat. - Nonprofit use of Deep Winter Greenhouses: Minnesota case studies
This report is helpful for urban and non-profit organizations that are looking to build a DWG. These case studies will outline some of the additional considerations that may be necessary. - Solar greenhouses
Author: ATTRA, National Center for Appropriate Technology
This site contains a large amount of helpful information about solar greenhouse design. - DWG PowerPoint presentation
This lightning talk demonstrates the basic principles of DWG technology using an 8-by-11-foot model.
- DWG enterprise budget and estimator
Producers can use these tools to estimate the revenues and expenses they might expect with a DWG enterprise. - DWG enterprise analysis
This research report examines the ability of DWGs to be viable business models. Results are based on analyses of eight deep winter producers in Minnesota in the winter of 2017-18. - DWG early tomato enterprise analysis
This enterprise budget allows users to examine potential costs and revenues of growing early season tomatoes in a DWG. The enterprise budget uses an Extension early season tomato research trial as the basis for cost and production information.
- Deep Winter Greenhouse production manual
Learn how to grow winter hardy crops in your Deep Winter Greenhouse. - DWG crop list
This is a list of crops that producers have found to work particularly well in the DWG system. - Deep Winter Greenhouse planter layout guide
Get advice and tips for building and laying out shelving for planters in a DWG system. - Research results from Deep Winter Greenhouse horticultural trials
This report provides recommendations for DWG producers using passive solar technology for cold tolerant crops like leafy greens. - Deep Winter Greenhouse tomato production trial overview and recommendation
Summary and recommendations from Deep Winter Greenhouse tomato production trails in 2021-2022. - Expanding the use of Deep Winter Greenhouses for summer tomato production: feasibility and profitabilityProduction and feasibility research results from 2021-2022 DWG tomato production trials.
- Yield of Leafy Greens and Microclimate in DWG Production in MN
Year one research trial results of DWG horticulture trials in DWG prototypes. - Soil nutrients in organically fertilized potting media under greenhouse conditions
This poster displays results of analyses of various potting soil mixes for the common DWG crops of mizuna, arugula and giant red mustard. - Day and night temperature effects on kale morphology and photosynthesis
This poster highlights research results on day/night temperature effects on kale plant growth. - DWG producer bios
These case studies provide the stories of three different DWG producers. Learn what inspired them to build a DWG, what drives them to produce, and lessons that only those with experience can tell. - Reinventing year-round local food production in Minnesota: Mid-term project report
This report highlights progress on a variety of research projects underway to look at the potential to maximize winter vegetable production. Results of analyses of day-night temperature effects on plant growth; vitamin C content of different fertilizer mixes; light response curves of kale; and vitamin C depletion rates are included. - Winter organic wonderland: Evaluating organic fertilizers for greenhouse production
This poster was presented at the Midwest Organic and Sustainable Education Services 2015 annual conference. The poster highlights results from trials that examined the performance of different fertilizers used in winter production.
Growing in a Deep Winter Greenhouse
In this Marbleseed Ag Solidarity Network video, Greg Schweser, Dan Handeen and Carol Ford present an overview of the Deep Winter Greenhouse program, providing a background on how the program came about, design and construction strategies and a primer on growing winter veggies.
Deep Winter Greenhouse: Heat storage systems and their trade-offs
DWG webinar from 2021, featuring Shannon Mutschelknaus (Wayward Springs Farm) and Dan Handeen (UMN Center for Sustainable Building Research). They share their experiences concerning heat storage and thermal mass applications in passive solar winter greenhouse systems.
Deep Winter Greenhouse Designs: DWG 2.0 and Farm Scale DWG
In this webinar from June 5, 2020, Dan Handeen explains the designs of the older DWG 2.0, the new Farm Scale DWG, and takes questions from the audience.
Growing plants in the deep winter greenhouse
This webinar from June 2, 2020, features Carol Ford and Shayne and Louise Johnson of Grampa G's Farm. Get a video tour of Shayne and Louise's DWG and learn about how farmers use these structures to grow winter vegetables.
Growing plants in deep winter greenhouses
This webinar from May 28, 2020, features Carol Ford and Brooke Knisley of Alternative Roots Farm. Get a video tour of Brooke's DWG and learn about how farmers use these structures to grow winter vegetables.
DWG research convening: November 4, 2016
Current and future DWG producers, RSDP staff, and University faculty, students and researchers discuss past projects and research and future research needs.
Watch the seminar or download the presentation (PDF). The 2016 DWG research convening summary provides an overview of the research convening and a list of project ideas and research topics that participants identified.
DWG history, design and future aspirations
University of Minnesota College of Design researcher Dan Handeen presents to the Minnesota Renewable Energy Society on the history, design and future aspirations of the DWG project (September 2016).
DWG research seminar: November 4, 2015
This research seminar, hosted by RSDP, highlights recent horticulture and building research projects involving DWG technology. Watch the hour-long seminar or download the presentation (PDF).
DWGs: An overview
A quick overview of DWG pioneer and author Carol Ford's DWG that presents the general concept of the technology.
The farm scale deep winter greenhouse initiative is supported by the Minnesota Department of Agriculture.