Commercial Sustainable Micro-green Production in a Northern Climate

View the project final report

• 2015 annual report

Commodities

• Agronomic: sunflower
• Vegetables: greens (leafy), peas (culinary)

Practices

• Production Systems: hydroponics

Problem

Micro-greens are becoming a widely sought after specialty crop among restaurants and the health-conscience public. In addition to wholesale markets, we have a growing number of clients fighting or recovering from serious diseases like cancer, that are delighted to have this nutrient dense product available for bulk purchase. However, in terms of sustainably producing micro-greens in the Upper Midwest, we have found a void of information on both techniques and profitability. There are many examples of small scale and backyard production of micro-greens but little to no on-farm commercial production, especially in our region. Nor is there research-based information on commercial production using sustainable practices. Though micro-greens can be a high-value crop, issues such as growing media, water quality and pH greatly affect plant health, yields, labor requirements and profitability. We believe, by changing growing media, adjusting our system, and implementing water controls we can produce a consistent, high quality, profitable product. We will also create an environment that will allow fish to thrive, therefore increasing sustainability by eliminating most inputs.

Soil significantly increases the risk of pest and disease pressure in micro-green production.   It’s prone to molds and fungus. Peat, which some say is being depleted, has many of the same attributes. This is a key issue. If we have healthy, mold free trays of micro-greens we are able to harvest using a cutting tool we’ve devised. We can slide a tray of micro-greens through the machine and cut it in less than a minute. If there’s mold or disease, we must cut the trays by hand with scissors to eliminate any diseased or poor quality micro-greens. This can take 10-15 minutes per tray. Hand harvesting can add 40-55 man-hours to our weekly harvest. This, along with poor yields, eliminates any potential profit and hinders worker satisfaction. There has been a movement toward coir, but this has issues as well because of the salt content in some varieties. More testing must be done.

The 2^nd key issue is water quality and pH. High pH causes micro-greens to become unable to absorb nutrients resulting in stunted growth, poor yields, and even total crop failure. In response, we measure our well water, amend it with acid (vinegar) and spray pump it to water the newly planted trays in their first days of growth (before roots go down into the rock-bed and absorb water there). This is a tedious, time consuming, daily task.

The 3^rd key is maintaining system pH. The rock base in our grow-beds is not pH neutral. Information I have read indicates the rocks negatively affect pH amendments and nutrient absorption, contributing to ongoing alkalinity problems. For long-term pH control our growing media, grow-bed base and water system must be in balance.

Solution

We began experimenting with soil-less mixes this year and though we’ve had several successes more research must be done to find consistent solutions.

We will test the 4 most common growing mediums: one commercially available organic soil-less mix, two types of grow pads, Sure2Grow and Micro-mat, and coir. We've tested perlite, and burlap layered with screen and found them to have poor yields. We’ve tested vermiculite and are uncomfortable with the level of dust it creates and the potential impact on our employees’ health.

We will control water pH at the pump by installing a reverse osmosis (R.O.) system that will allow us to filter and amend the water before it goes into our system or onto the plants.

We will test clay balls and bio-balls as two different pH neutral grow-bed bases to replace the rocks in our system.

The one-year project timeline is as follows:

Summer 2015 – Purchase supplies. Prepare the four experimental grow-beds. Remove rock currently being used as the filtration base and refill both grow-beds in one closed loop system with bio balls and both grow-beds in the second closed loop system with expanded clay balls.  Install filtration unit that will control water pH.

Late Summer, 2015-Spring 2016 – Conduct project experiment. As a business we need to maintain our scale of production, so we will do our test in stages.

Stage 1: Prepare and plant 4 trays of kale micro-greens, with one of the four soil-less mediums. Put 2 of these trays in grow-beds containing clay balls and 2 in grow-beds containing bio-balls. Water and add nutrients, as we normally would do.

Due to the extraordinary number of variables in growing micro-greens, ie: greenhouse position, weather, humidity, sunlight, temperature, disease, etc., we will test for two growing cycles, 10-14 days each. We will evaluate and record data in regard to labor, ease of planting, plant growth and health, yield, ease of harvest, pH of water and soil and any other relevant observations after each cycle.

Stage 2: Repeat this process with each of the 3 remaining growing mediums.

Stage 3: Repeat Stages 1-2 with mustard micro-greens.

Stage 4: Repeat Stages 1-2 with broccoli micro-greens.

Stage 5: Repeat Stages 1-2 with radish micro-greens.

Stage 6: Evaluate our results and fill an entire grow-bed system with trays using the medium that produced the best results in stages 1-6.   Evaluate the affects of large-scale usage according to pH variations and system stability, in addition to plant health, production, disease resistance, labor requirements, and ease of harvest.

Submit a progress report by the December 30^th deadline. 

Spring 2016 – Finish experiments, summarize data, and write final report for NCR-SARE.  Present information learned through our outreach efforts.

1. Determine if soilless, organic micro-green production in a hydroponic system can be a profitable, year-round farm enterprise in Northern climates.
2. Benefit the environment by developing this growing method, which uses a sustainable growing media and less inputs.
3. Enable farmers to increase their profitability by maximizing yield of healthy plants.
4. Share results with a wider audience through articles and news releases, updates to farm website and Facebook site, county newsletter, and other agriculture papers.