Creating a Sustainable Year-Round Greenhouse Cropping System Using Straw-bale Culture and LED Lighting

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2009: $6,000.00
Projected End Date: 12/31/2011
Region: North Central
State: Minnesota
Project Coordinator:

Annual Reports


  • Fruits: berries (strawberries)
  • Vegetables: greens (leafy), peas (culinary), peppers, tomatoes


  • Crop Production: continuous cropping, organic fertilizers
  • Production Systems: general crop production

    Proposal summary:

    It is not unusual for diverse small farms such as ours to have a greenhouse for seed starting or high value crop production. These structures are often simple, but generally may have two layers and a source of heat and electricity. The construction of these greenhouses while justified, is a substantial investment, both economically and environmentally. The problem is, they almost always sit empty from July through February. We would like to create a system that extends the greenhouse growing season, without adding substantially to the energy resources required. Focusing on a cropping system that allows for a year-round greenhouse operation rather than building additional greenhouse space is the primary goal of this research. Additionally, we want to find a use for the by-product of an organic grain or pasture. Straw or hay that can be used as a growing container, bottom heat for plug production and a passive heat source, then as a mulch and finally as a compost, fulfills our farm mission of creating durable and symbiotic enterprises.

    For much of the year in Minnesota" light, rather than heat, is more of a limiting factor when trying to produce a crop out of season. There are a number of crops that can be maintained under cool conditions or that can be forced early using a simple covered structure. Lack of daylight however is more difficult to overcome for all but a few crops. The emergence of energy efficient LED lighting may provide a solution. LED lighting provides the ideal light spectrum for plant growth while using substantially less electricity then HID or florescent lighting.

    Straw-bales have multiple potential positive when used as a "container" in a greenhouse. When prepared with a compost tea and topped with a growing medium such as peat and worm castings, they begin a composting process that can generate COz as well as heat to the root zone and even the surrounding environment when enclosed in a structure. They afford easier harvesting of crops due to their raised bed effect, can help maintain moisture, can be used multiple times and can eliminate the need for plastic mulches or plastic containers.

    The primary focus of this research is to create and evaluate a yea.r-round growing system that utilize a combination of LED lighting and straw-bale culture as a sustainable alternative to traditional greenhouse production. We will explore this approach by using a double-covered poly house(I4'x 36') and above ground growing so that seasonal greenhouse conversion and infrastructure would be minimal. Organic and sustainable cultural practices will be maintained. The objective would be to create three growing seasons for the organic production of high value crops such as tomatoes, peppers, strawberries, herbs and salad greens in straw-bales using supplemental LED lighting when needed. We will try various crop rotations while maintaining a rigorous evaluation of the economic impact of each cropping schedule. The goal will be to generate $10-15 per sq ft of greenhouse space per year.

    The soilless medium used on the straw-bales will be a peat and worm-casting mix. Sustain fertilizer will be used along with blood meal and compost tea for fertility management. Bees will be brought in to the greenhouses for pollination when needed. We will monitor environmental conditions such as accumulated growing degree days and minimum and maximum temperatures.. Crop quality data such as disease and pest pressure and harvest data such as time to harvest and yield totals will also be monitored.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.