Although many growers would love to have covered growing space, the cost of building even an unheated high tunnel (or hoop house) can be prohibitively expensive. Caterpillar tunnels are a low-cost alternative to traditional hoop houses and offer many of the same benefits as well as some additional ones.
Caterpillar tunnels are much smaller than most hoop houses. They are typically 8 to 10 feet high and 12 to 14 feet wide, and they can be 25 to 100 feet long. Also unlike hoop houses, caterpillar tunnels are designed to be semi-permanent and are fastened together using nylon rope. The rope holds down the plastic by zig-zagging across the top of the tunnel between each pole, creating a caterpillar-like appearance that gives the tunnel its name.
Here are several of the key benefits that caterpillar tunnels can offer, especially for beginning farmers.
1. It Costs Less Than a High Tunnel
Generally speaking, a caterpillar tunnel costs several thousand dollars less than a permanent hoop house. Many companies sell complete caterpillar tunnel kits, but the frugal grower can save even more money by downloading a parts list online and buying almost all of the components from the hardware store.
2. You Can Move Your Tunnel With You
Unlike traditional hoop houses, caterpillar tunnels are designed to be relatively portable. Two people can set up the tunnel in a few hours and take it down in approximately the same amount of time. This portability comes with several advantages. If you live in a climate with a harsh winter, for instance, you can easily take off the plastic to prevent wear and tear throughout the winter, or even take down the entire house. Additionally, if you’re beginning your farm on rented land (as many young or beginning farmers do), you can easily disassemble a caterpillar tunnel and bring it to your next farm plot
You can also move your caterpillar tunnel around the farm throughout the growing season to cover different crops at various stages of growth. Because driving in and pulling up the ground posts is the most time time-consuming part of moving a caterpillar tunnel, you can buy an extra set of ground posts so you can move the tunnel from one location to another more quickly.
3. It Lets You Promote Soil Health
Additionally, the portability of caterpillar tunnels can also help you maintain the soil health of your growing areas. Because it doesn’t rain inside tunnels, soluble salts including nitrate, potassium and sulfate can accumulate in the soil over time. With a caterpillar tunnel, however, you can easily avoid this problem by removing the plastic from the tunnel a few times throughout the year for a period of several weeks, or by moving the caterpillar tunnel back and forth between different locations.
4. It Can Expand Your Growing Knowledge
Finally, caterpillar tunnels can be a great way for a new farmer to learn the basics of season-extension growing before investing in a more expensive hoop house. The relatively small amount of growing space inside a caterpillar tunnel can, for instance, be a great place to familiarize yourself with growing techniques and plant varieties that are well suited to conditions inside the tunnel.
Before You Buy a Caterpillar Tunnel
There are, however, some things to consider before purchasing a caterpillar tunnel for your farm. First, caterpillar tunnels are more prone to wind or snow damage than conventional high tunnels. Although caterpillar tunnels can be stabilized in various ways, including installing purlins, cross braces or even a wooden frame around the base, all these add-ons also make the tunnel less portable.
Additionally, the interior space of a caterpillar tunnel can be somewhat limiting. It can, for instance, be difficult to access the outermost beds inside the tunnel because of the relatively low height of the tunnel itself. The height of a caterpillar tunnel means that there is not a large amount of vertical space in which to grow trellised crops such as tomatoes or cucumbers.
All things considered, though, a caterpillar tunnel can provide a beginning farmer with a great first step into season-extension growing.