Economical Climate Control for extended Production in High Tunnel Vertical Growing Systems

Project Overview

Project Type: Farmer
Funds awarded in 2010: $7,651.00
Projected End Date: 12/31/2012
Region: Northeast
State: Maryland
Project Leader:
Allen Lilly
Ryan's Glade Farm


  • Fruits: berries (brambles), berries (strawberries)


  • Crop Production: double cropping, irrigation
  • Education and Training: extension, farmer to farmer, mentoring, networking, on-farm/ranch research, participatory research, technical assistance
  • Energy: solar energy, wind power
  • Farm Business Management: new enterprise development, cooperatives, marketing management
  • Pest Management: chemical control, compost extracts, mulching - plastic, row covers (for pests)
  • Soil Management: soil chemistry, organic matter
  • Sustainable Communities: new business opportunities, sustainability measures

    Proposal summary:

    Everbearing strawberry plants have been shown to be highly productive and of high fruit quality when grown in cooler climates, such as found at 2500 ft elevation in the Appalachian Mountains or in northern New England and Quebec. The cool weather allows development of larger fruit as well as slowing down the ripening process and maintaining sugars and fresh firmness. In the eastern US, these locations have very short growing seasons <120 days therefore everbearing plants must be establish and produce fruit in this short time. Starting with large plug plants partially reduces the time for establishment, but production hits its peak in late August and September. As first frosts are in mid September in many years, growers would benefit from extending the growing season. Throughout the world, growers have used high tunnels to produce strawberries with reduced or no pesticides. The tunnels reduce the ability of many of the fungi and bacteria to move from plant to plant by protecting plants from rain. The rain also causes spotting on fruit, reducing storage life and marketability. Depending on the tunnel and management, tunnels can extend the length of the growing season. Unfortunately, even with a thermoblanket, most tunnels do not provide adequate protection from temperatures below 200F, a common temperature in fall in the above locations. Although heating with fossil fuels is a possible solution, fossil fuels are expensive to use in non-insulated structures such as tunnels. We propose investigating the cost effectiveness of using what some consider “waste energy” from two alternative technologies, wind and photovoltaic solar to produce heat during the winter. Each of these systems will be used to heat the same insulated tank of water. To enhance the delivery of the warm tank water, we propose using a vertical growing system (column) for strawberry plants. We will attach a tube inside the growing system and allow the tank water to flow through the system to modify the climate near the strawberry crowns. The vertical grow system also maximizes the amount of plants inside of the high tunnel allowing for a greater number of plants to be fruited with the same amount of heat energy. We propose using our ample wind to heat water for use in protecting the greenhouse from fall and spring frosts. In the US, we found only one SARE report which used wind to move water, Betty Rodriguez, Wyoming (FW03-004 SARE Farmer Grant) but this was to provide energy for irrigation.. For those people not on the grid, it is common to “dump energy” by heating water. We plan to heat the same tank using electric heating elements, this technology is not new or noteworthy. We also have photovoltaic cells that can be used to supplement this heating and run the pumps. Again, the system would be similar to that used for dumping excess energy. The use of vertical grow systems is well known for strawberries. A quick search of the web indicated at least 10 sites advertising some sort of growing apparatus. There was a talk delivered about them at the Hershey PA Meetings in February 2009. We are personally familiar with two systems, one a homemade rigid pipe system with a single irrigation tube with resistance every 12 inches in Washington State and the other, a plastic ”fruitwise” film system sold by Agrivista in the UK (we have a FOB price quote from a supplier). This fruitwise system (shown below) is a segregated (segmented) column. The effluent from a module drains into the central column. The excess moisture from the module above does not come into contact with the one below. Each module is independantly irrigated and independantly drained. There is therefore an equal distribution of moisture to each plant. This system is the one we will choose to use (approximately $30 for 36 plants) and even an inexperienced grower has produced 60 tons per hectare in the first year with Sweet Eve day neutral strawberries. We are unaware of any attempts to marry this type of heating technology to any vertical grow system, but this system already has a drainage pipe to allow insertion of a PEX tube through the column . Over the last four years, Ryan’s Glade Farm has grown around 2000 everbearing strawberry plants in raised beds. First year yield has been (depending on treatments like film color –black, silver-white or flower removal treatment) very good, typically 1.5 lbs per plant. Fruit size is consistently over 12 grams. Heavy rains reduced the percent marketable fruit, and forced the use of a fungicide. This year has made it clear that we must use tunnels in our region for day neutral varieties like Seascape, Everest and EV2. All of our farm’s produce including peppers, tomatoes, squash, cucumbers, cabbage, broccoli, etc is marketed at the Oakland Farmer’s Market- which celebrated its 35th year. Strawberries are a major source of income and we would like to expand to plantings in tunnels which would improve quality and expand the growing season. I have limited amount of space to add high tunnels therefore I have purchased a heavy duty high tunnel that would allow me to use a vertical growing system instead of using lighter weight tunnels and growing in the soil. We receive over $3 per pound for our fruit, and expect $4 per plant in the first year. Thus, the economics of a more advanced production system is warranted.

    Project objectives from proposal:

    We have built a 20 x 72 foot tunnel with double polyethylene sheets inflated with a squirrel cage fan. On one end of the tunnel, we will build a 958 gallon = 8 ft x 4 ft. x 4 ft deep concrete block storage tank lined with a double layer of 2-inch thick Styrofoam for an R value of 20. Over one day, this tank will be expected to lose about 230 BTU per degree F difference with the outside and ground temperatures. We will insert five 12 V 600 Watt “Power dump” heater elements with the capacity to add 10236 BTU per hour to the water, enough to increase the temperature of 1000 gallons 0.71?F (per hour). We will power these heaters with 18 volt photovoltaic panels and with 3 1-kWh wind generators (turbines), which we will erect. We will start heating in the early fall to heat bank our tank.

    To deliver this heated water, a copper tube will be inserted into the tank; it will be attached to a submersible fountain pump. The output of the pump will be several one inch polyethylene tubes which will be run through the central drainage of vertical grow columns. For this work, the vertical columns will be placed 3 ft in the row and 5 feet between rows (9 per row x 4 rows). The return pipe will be run from the top of the next column back to the main on the ground. The Fruitwise vertical growing system will be as shown on the next page in the United Kingdom, at a friend’s farm. Each upright tube consists of 9 “links” arranged as a string of sausages.

    The vertical grow systems will be planted with the following strawberries:
    row 1. Seascape,
    row 2. Albion,
    row 3. EV2,
    row 4. Sweet Eve,

    40 additional potted Marcianna fall bearing raspberries plants will be included; the water tube will be wrapped around the pots to heat the roots for quicker spring growth.

    For the Plants.
    Three random vertical tubes per variety will not be heated (i.e. no polyethylene tube will be used). To measure the temperature effects, there will be a three of probe temperature type thermometers in both non heated (control) and heated/cooled (treated) vertical grow systems and in the water tank. Temperatures will be monitored daily during test days (described below). Probe type thermometers will be placed in the soil at the top and bottom of the column. Vertical column soil temperature data will be taken at 9 AM and 4 PM during test days. In summer and again in winter, we will do airspeed tests on 4 bright sunny days and 4 cloudy/rainy days (32 days in all). Data on fruit yield and size will be taken for 3 treated and untreated tubes per variety and over the entire season. The experiment will be envisioned as shown.

    To measure the effects on plant growth and yield, three treated and untreated columns will be harvested separately and fruit weighed and counted for fruit size determination. At the end of the year, the number of crowns will be counted on the plants on the test columns as a determination the plant’s reaction to the soil temperature. A multicrowned plant can be an indication of too much crowding, perhaps reducing fruit size. Branching is thought to be a reaction too much heat, much as truss branching (and smaller fruit) occurs in hot weather.

    For the System.

    We will be interested in several other questions outside the effects on plants. Therefore we will take temperature data every couple of days on the storage tank, outside and inside the greenhouse.

    We are anxious to find out:
    How efficient will the Polyethylene PEX tubing and vertical tubes be?
    How hot will the tank become?
    How much protection from the cold will the system produce?

    The difference in temperatures between Garrett County and, for example, sea level New Jersey both at the same latitude, but 3000 ft in elevation different are close to 100F on average. We are proposing this project to help our farm produce higher quality fruit for a longer period, but its results will have similar impacts for everbearing strawberry growers who cannot grow fruit during the hot summers but rely on fall cropping and early spring fruit.

    For growers of various crops which are suitable to fall and winter production, we are proposing a heating system that will not use a lot of external or carbon based energy to operate. We are also trying to adapt the vertical growing system to other crops, perhaps grape wattles and certainly vegetables.

    Our target audience will be local strawberry growers as well as tunnel and greenhouse growers in the Northeast and Northcentral regions. An open house type field day will be held in the fall of 2010, so interested individuals can get a first hand look at the system. Invitations to the open house will be sent out to 1000 farmers through out the northeast as well as internet postings and e-mails to extension faculty through out the northeast.
    We will share our final results with farmer through our newsletter and a fact sheet. The factsheet will be made available throughout the northeast. We will also request to be speaker at regional fruit and vegetable meetings.

    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.