So You Want to Put up a Hoophouse?
This article was first printed in the May/June 2010 issue of the Organic Broadcaster, published by the Midwest Organic and Sustainable Education Service.
Hoophouses are sprouting up like mushrooms (they can even look like mushrooms!) across the Upper Midwest. Markets have opened for local foods, encouraging farmers to “extend” their season beyond what they could produce without this extra protection. The investment in this infrastructure can have fairly quick payback, from both the higher prices “out of season” production can claim, as well as the higher quality and volume of produce you can reap from inside these structures. The Natural Resources Conservation Service (a program within the USDA), has recently offered cost share dollars for the construction of unheated hoophouses or high tunnels (we will use the words hoophouse and high tunnel interchangeably). This support is in recognition of the controlled environment created within the structure, which can encourage more judicious use of fertility, pest and disease control inputs and result in the protection of water and soil quality, which is the key NRCS goal.
There are many excellent sources of information on how to construct a high tunnel, where to purchase a kit or how to put one up using a variety of materials you can buy locally. Information on how to successfully grow a variety of crops within a hoophouse is also readily available and increasing every year. MOSES, in partnership with the Minnesota Institute for Sustainable Agriculture (MISA) and the Institute for Agriculture and Trade Policy (IATP) recently launched the Midwest Season Extension website, www.midwestseasonextension.org. There you can find links to great Kansas State and University of Minnesota websites and listservs as well as many other helpful resources and the latest happenings in the hoophouse world.
Here we would like to run through some basic questions that you should consider, along with some ‘learn from our mistakes’ examples, to help you build a hoophouse that will be relevant to your operation as well as highly productive and flexible enough to keep you producing crops for years to come.
A Perfect Site is Key
Like any field where you would plant, you will need your hightunnel site to have good drainage. This is one of the most important aspects, second to site selection. The last thing you want in the spring, when you are excited about working outside and getting your seedlings in the ground early, is to be dealing with standing water from melting snow and ice. Nothing will delay your early planting more than beds that are full of water. Water and snow running off the high tunnel, unless managed properly along the sides through either buried trenches with stone and drain tile or other mechanisms, could result in some very soggy areas within your structure. This can cut into your growing area, lead to disease, and damage your profits.
If you plan to move the tunnel from location to location every few years, how much do you want to invest in this runoff management, and how can you design your structure site so it can be used as a regular field in the future? Having buried rock and drain tile would not be disc-, field cultivator- or rototiller-friendly. Landscape cloth or heavy mil black plastic might be one solution, perhaps even laid in a shallow ditch with a slight slope to carry away water from the sides of the hoophouse. This would still take some work to remove when you dismantle your high tunnel in the future, but would be less work than taking out rock and drain tile. Still, if you plan to have the tunnel in the same place for many years, the better you plan for this water the less trouble you will have. Ultimately, selecting an ideal site with land that slopes away from your structure will be much easier and much less costly in labor and materials than a highly engineered drainage ditch.
Another factor to consider when deciding what type of hoophouse to build is personal comfort while you are working. This is one of those things that many of us do not consider until we can’t stand up straight because we have been stooped over for too many hours working in our hoophouse. If you are building a hoop with straight sides, you will have more room to stand up and work in the outside rows. If you build a hoophouse with curved sidewalls, you will not have much head clearance on the edges. Also, think of bed size and walking path spacing. Our first year we wanted to use as much space as possible for growing so we could make the most money out of every square foot. So we made our walking aisles about 12” wide. This was a disaster, and made working in our hoop uncomfortable. Not to mention the lost produce when we lose our balance and step into our bed of $7/lb. salad greens. Make sure you give yourself enough room to work comfortably. Trust me, with the extra value your out-of-season produce will have, you can afford to give yourself enough space to walk and work between beds.
Get the Soil Right
Planning the Hoop to Fit Your Production
If you are planning tomatoes or cucumbers, will the high tunnel be constructed strongly enough so that you can tie your plant trellises to the greenhouse? Or will you plan to build trellises that are free standing? There are many options for trellising depending on what you are growing. This is where talking to other growers can be helpful. They have many creative ideas about trellising.
Remember that for annual crops you cannot, under organic regulations, grow the same annual crops year after year in the same “field.” This regulation is in place for a good reason, and the hoophouse is just like any other field on your farm. Soil fertility and management are the foundations for healthy crop yields as well as pest, disease, and weed control. Crop rotation is critical, so you need to consider what your rotations will be within that greenhouse, to both meet your market needs as well as promoting healthy soil and nutrient cycling.
Keeping the Hoop Productive
Do you plan that this hoophouse will remain in the same location for 10 or more years, or do you anticipate moving it (taking it down completely, not the moveable high tunnels on skids) to a different location? If you are not planning to move it, you will need to consider how you will deal with salt build up and compaction of the soil. How you lay out your rows from year to year and the type of watering you do will affect this. Drip tape will not compact the soil as much as overhead watering from a wand or sprinkler will. By having permanent beds and walking paths, the risk of compaction to the soil is lessened and makes amending the soil easier.
Water Issues Are a Critical Consideration
Sprinklers can work, however, you will need to be careful about the time of day you water. Try not to leave too much moisture on the leaves of your plants, as this will tend to lead to disease and fungus problems. Water early enough in the day to give your plants plenty of time to dry off and you should be fine.
If you are not growing through the winter, and only growing from late spring to late fall, you can probably get by with running a hose. But if you plan to water in the hoop through the cold, snowy days of winter, what is your water source plan? A large tank that serves your drip tape system with a stock tank heater might be one solution. You would still need to fill the tank, but not as often during the winter. Unless we have a lot of sunny days, you will probably only need to water once every 10 days or so. Overwatering can be a problem too, since cold wet soil and plant leaves can lead to fungal problems.
Planning for Cold
We hope you give some thought to these questions and that they help you develop the answers for your own situation and farm plans. Take the time to attend field days or even just visit other folks who have high tunnels and see how they have dealt with these various issues. You can learn a lot from what other farmers have developed and what they have decided was not satisfactory. If you have an NRCS cost shared hoophouse, you must track how this is lessening your use of pest control products and protecting ground and surface waters from soil fertility product leeching. Tracking these items will help you learn how best to use your high tunnel, both for fun and profit!
Harriet Behar is the MOSES Organic Specialist, and Angie Sulivan is the MOSES Resource and Events Coordinator. Both have diversified vegetable farms featuring productive hoophouses.Return to TOP