The cost of high tunnel and greenhouse infrastructure is high. The purchase price of high tunnels can vary between $2.00 and $7.00 per square foot, while climate controlled greenhouse costs can vary between $7.00 and $30.00 per square foot. Several factors have an impact on the costs of setting up new high tunnel or greenhouse infrastructure.
- Location – It is essential that the terrain selected for the construction of high tunnel and greenhouse infrastructure be well drained and level. High tunnels and greenhouses displace rainfall and provision has to be made for drainage infrastructure to redirect the water. Additionally, provision has to be made for new irrigation lines and if necessary, electricity and gas. As a general rule the distance of high tunnels and greenhouses from obstacles like trees or a building should be twice the height of that obstacle. This also applies to the distance between high tunnels or greenhouses when they are orientated east-west. When the orientation is north-south the distance can be as little as 4 feet between the tunnels. Windbreaks can be an important protection strategy if your farm is located in a high wind area. The effectiveness of windbreaks, i.e. trees or structural, is determined by its height, density and orientation, and should be on the northwest and southeast side of the infrastructure. Furthermore, the distance of your farm from contractors and vendors can increase the cost of infrastructure development.
- Crop Type and Growing Environment – The type of crop grown (warm weather or cool season), the climatic conditions at the production location, and the main production season targeted will determine the specifications of the infrastructure and equipment necessary to produce the crop; i.e. warm weather crops produced in colder climates during the winter will require a higher level of investment. Considerations will include, but are not limited to, the snow load of the structure, the type of glazing material used and the amount of additional heat and light that needs to be provided. Similarly cool season crops that are grown during the hottest time of the year will require systems that can cool the production environment. If a crop is grown that requires trellising, then there is a need for a crop support system which either can be fixed to the high tunnel or greenhouse or can be a stand-alone system within the infrastructure. The type of crop, the growth substrate and container used, and climatic conditions will determine the type of irrigation system used.
- Size and Technology – High tunnels can vary in size, anywhere from 20 ft. wide and 48 ft. long to 34 ft. wide and 96 ft. long, along with variability in height. Questions to ask when choosing the structure design and options include:
- Do I need gable shutters or a continuous ridge vent, and roll-up windows on the side?
- Are the shutters, ridge vent and roll-up windows going to be manually adjusted or will it be automated?
- How high do I need the roll-up windows to open; 4 ft., 5 ft. or higher?
- What is the end wall going to look like and what material will it be made of?
- Which additional climate (i.e. screen, extraction and circulation fans, misting, wet-wall, boiler, propane heater) and irrigation equipment and control systems will be required?
- Which floor covering material will be used?
- Which glazing material am I going to use?
- If it is plastic, will it be a single or double layer?
Similar to high tunnels, climate controlled greenhouses can vary in size, but one greenhouse can also cover several acres. The level of sophistication in gutter-connect greenhouses can also vary significantly.
It is clear that infrastructure costs are influenced by many factors. But what is certain is that the cost per square foot is driven by size, design and equipment needs. Usually smaller high tunnels and greenhouses cost more per square foot. Similarly, a more extensive and complicated design with the additional need for more equipment will result in a higher cost per square foot.
More importantly, the crop type, production window targeted, consumer demand and price will determine when a crop is produced and the level of infrastructure investment needed. A higher investment in a fully climate controlled greenhouse will result in better yield forecasting and ultimately higher yields of high quality compared to a high tunnel. It is imperative for the grower to do a comprehensive economic feasibility study and life cycle analysis to compare implementation costs between high tunnels and greenhouses to gains from increased production capacity and quality. Existing or new farming enterprises need a business plan that can help with the decision making process. Dr. Maria Marshall, a professor at Purdue University’s Agricultural Economics Department, developed an online business planner that can help you write a business plan using a question and answer format. The INventure Business Planner tool can be found at http://www.purdue.edu/newventure/.