High Tunnel vs. Greenhouse: Which is Right for You?
WHAT IS THE DIFFERENCE BETWEEN A HIGH TUNNEL AND A GREENHOUSE?
The main difference between a high tunnel (sometimes referred to as a hoop house) and a greenhouse is that a greenhouse is a permanent structure with some type of climate control. In contrast, hoop houses are only meant as a tool for season extension and are semi-permanent. You will often find swamp cooler-type wet walls, ventilation, and sometimes heating units in greenhouses.
A greenhouse will have a cement slab foundation or semi-permanent flooring like compacted gravel. Depending on the type of greenhouse and the location of the greenhouse, some growers may use this structure year-round. The type of covering used on a greenhouse will typically be rated for more wear and tear than your typical poly cover. Greenhouses will most often have rigid polycarbonate sheeting, while hoop houses are typically covered in plastic film.
HOW ARE HIGH TUNNELS AND GREENHOUSES USED DIFFERENTLY?
Traditionally, greenhouses fall more in the commercial retail sphere since they're spacious and anchored to the spot by some form of foundation. They are used for plant propagation before crops are moved outdoors and for growing more tender crops to full adult size. Commercial growers commonly use greenhouses to propagate and plant up house plants, tropical plants, and succulents.
On the other hand, high tunnels are more often used for growing crops in-ground. However, with the right size high tunnel greenhouse kit, seed propagation, potting and repotting can all be done comfortably and successfully.
Both greenhouse styles are used to extend the growing season by protecting crops and other plants from low temperatures and the elements. With the addition of ventilation and shade cloth, both structures can also be used to protect plants from excessive heat and sun-scald.
HIGH TUNNEL VS. GREENHOUSE
The most significant difference between the structure of a greenhouse and a high tunnel is that a greenhouse is permanently (or semi-permanently) anchored to the ground by a concrete foundation or footers. A high tunnel, or hoop house, consists of a series of hoops attached to ground posts driven into the ground with a ground post driver and a sledgehammer. Although this is a labor-intensive process, it can be deconstructed and moved to a new location if needed. Before you place your high tunnel, read our article on Ideal Greenhouse Location and Orientation.
Finally, greenhouses usually have permanent utility hookups for ventilation, heating, and lighting. Whether or not you can hook up utilities at the site will be a huge consideration as they will require extra cost and permitting. High tunnels may include some of these elements but generally not all. Hoop houses simply act as a line of defense between crops and the outside world. If the added climate control components are absent, often growers will rely on extension cords to run a space heater for short periods to get crops through a cold snap.
What Kind of Plastic Do You Use for a Greenhouse?
Greenhouses will generally have harder forms of glazing for their wall structure, like glass or polycarbonate panels. They can be covered with plastic film, although most greenhouses will rely on the thicker woven poly if not using hard sides.
For a high tunnel or hoop house, the best compromise between price and durability comes with 6 mil greenhouse plastic as it is treated to be UV resistant. Be sure the plastic you are buying is intended for use in direct sunlight and has this treatment. Regular plastic sheeting, such as the type used by painters to protect carpets, is not designed for long-term outdoor use. Check out How to Attach Plastic Sheeting to a Hoop House for a deeper look into film attachment and the best attributes to look for when sourcing greenhouse plastic.
BENEFITS OF HIGH TUNNELS
While a high tunnel greenhouse is not generally as sturdy as a traditional hard-glazed greenhouse, it still offers a variety of unique benefits. Check out Why Should I Build a Hoop House for a more thorough understanding of hoop houses and how they help with season extension.
Top 5 Benefits of High Tunnels
- High tunnels allow ventilation without the need for a dedicated system thanks to their open-ended doors and the film used to cover them, which can be easily rolled up using a sidewall ventilation hand crank to allow even more airflow.
- High tunnel greenhouses are less expensive to construct and operate.
- High tunnels can accommodate in-ground growing, making them ideal for quick rotations of seasonal crops.
- High tunnels can be used to protect seedlings from before they are moved into outdoor rows allowing you to get a significant head start on the growing season.
- High tunnels give protection from hail, wind, frost, excessive precipitation, and pest pressure.
BENEFITS OF GREENHOUSES
Greenhouse structures protect from extreme elements and give the plants a more consistent growing environment to thrive in year-round. They are often equipped with climate control and have greater insulation values resulting in a higher holding capacity for heat. These features add to the overall cost of running the structure.
Top 5 Greenhouse Benefits
- Greenhouses can be used year-round if equipped with heating and cooling equipment.
- Greenhouses offer more protection from the elements since they are completely enclosed and made of polycarbonate panels or glass.
- Greenhouses have a solid foundation or flooring to accommodate growing systems, benches, and other infrastructure.
- Greenhouses allow for more plant options, i.e., tropicals or more finicky plant varieties, as the variances in the environment are minimal.
- Greenhouses allow for efficient pest management as the space is more securely enclosed.
Do I need a high tunnel or a greenhouse?
The decision on whether to invest in a greenhouse or a high tunnel/hoop house will depend on the scope of use the structure will need to perform. If your operation does not require a permanent structure with the ability to serve your needs year round, don’t invest in it. That money is better spent elsewhere.
If you plan to try a year round operation in an area with dramatic temperature swings, forcing a hoop house to serve that need will not be cost-effective and will only be an up-hill battle. Make your decision based on both your current and future needs.
Another option to explore is the difference between high tunnels and caterpillar tunnels. We have written High Tunnel VS Caterpillar Tunnel: Which One is Right for You?, examining the key differences between the two structures.
How big do you want your farm to grow?
Another consideration is your level of experience with gardening or farming and how large your operation is going to be. High tunnels are great for beginners, offering a lower price point for bootstrappers who are just getting started or who want to test a new kind of growing. Larger ones can even work well for seasonal commercial operations such as plant retail nurseries, hydroponic systems, and large-scale year-round crop production. If you need greater functionality, high tunnels can also be combined with traditional greenhouse design elements such as gable vents, heating and wet walls to create the ultimate nurturing environment for your plants.
How can you get help paying for a high tunnel or greenhouse?
There are grants available that farmers and gardeners can use to fund their hoop houses. The High Tunnel Initiative from the United States Department of Agriculture (USDA) is a grant that focuses on equipping farms with hoop houses, but it comes with some conditions. The program provides financial assistance to farmers who invest in high tunnel systems to extend their growing seasons, enrich their soil and limit energy consumption and the use of pesticides.
It's a great way to get a new project off the ground! Keep in mind that this grant program requires you to plant crops directly in the ground because the funding is in part for soil improvement. It does allow for raised beds of no more than 12 inches in height. Greenhouses do not qualify for this type of funding through the USDA EQUIP program but other forms of infrastructure may be covered.
Before you begin building your high tunnel or greenhouse
The process of building either of these structures requires some amount of foundational work before you build. Even a high tunnel that will be used for growing crops in the ground will need to have the ground leveled and possible drainage issues considered before construction begins.
A greenhouse will require more preplanning, particularly if you will be laying a foundation or pouring a concrete floor. With current supply chain issues and construction company backlogs, if you will be needing to rent equipment or pour a concrete slab, be sure to check on local availability before you schedule your build.
We have a number of resources to help you plan for your site preparation. You can use silage tarp to eradicate weeds long before you build to ease the process. Take a look at this short video from our greenhouse experts to get you heading in the right direction. Hoop House Site Prep | HOOP HOUSE 101 Ep5
Once you have decided which structure is going to work for your farm, both in terms of budget and growing needs, it is a good idea to do some further reading. Our Prequel to Building a Hoop House is a great place to start. If you have particular questions and learn better from watching than from reading you can pursue our entire YouTube playlist on Hoop House 101 here. It is designed for you to be able to watch as a series in order, or to jump around to the parts of the process that are of interest to you.
One of the first things that we recommend you do first is decide where you will be placing your structure. There are many factors to consider including wind direction, shade trees, existing structures and access to utility lines. To help you make these decisions we have written this article on Ideal Greenhouse Location and Orientation.
Choosing a High Tunnel or a Greenhouse
Whichever option you choose, we recommend doing your research and planning ahead with farm expansion in mind. Greenhouses and hoop houses can both serve fundamental roles in a larger scale market garden operation or farm. Both can also have a place at the homestead or in the home garden. If you want to see how the bootstrappers that we know are using their high tunnels and hoop houses be sure to follow us on Instagram where we share photos and videos of our favorite farmers.
Hoop houses offer many of the benefits while being far more budget friendly. Once the house is built the only real ongoing expense will be replacing the poly film. If well maintained, 6 mil UV resistant greenhouse plastic film will last far beyond the 4 year warranty.
Greenhouses add a lot of expenses that will need to be made up for every year in power, added infrastructure taxes, and the ongoing maintenance that comes with them. Panels on greenhouses have an expiration date, so that is a large expense that will come into play around 5-8 years into its use, especially if you need to hire a contractor to install them. If the crops you intend on growing will easily make up for the accrued cost, this investment might be justified for your operation.