Renewable, natural and compostable. Often available for free. Those are the main reasons why I’ve been making hoop house cloches with bamboo, and now’s the time to get some bamboo and try it, so they will be
ready for covering spring crops.
If you’ve heard my presentation on building a cloche, you know that I don’t think very highly of PVC. The white plastic pipe that is the standard product for building a hoop house cloche in our region is actually kind of a nasty choice. It’s the opposite of all those adjectives I used for bamboo.
I want to focus on how to make a cloche with bamboo, but first, a couple of quick comments about PVC.
Polyvinyl chloride pipe is a traditional plumbing product, quite necessary in some applications, and is readily available for only a couple of bucks a piece. But its cheapness hides its cost to the environment. In the manufacturing process, production of it gives off dioxins, a known carcinogen, which sickens workers and affects the environment. It’s not readily recyclable and would live in a landfill forever. (Learn more than you want to know at Wikipedia’s PVC page, which includes plentiful links to sources and studies.)
I used PVC for years, but as I learned more, I started to move away from it, and looked for other products for my cloche. Fortunately, I found a few options:
Each of these products has their benefits and drawbacks. Wire lasts a long time, but it is not very sturdy, so the hoops are a bit wobbly and have to be placed pretty close together. Wire mesh is more difficult to remove when you want to work in the bed. Fiberglass poles can get brittle and snap if made into a tight hoop, and I haven’t found ones that are very long, so a cloche made with them is shorter. Poly pipe, the black stuff used in garden irrigation systems, gets soft in warm weather and gets floppy (however, it doesn’t have the nasty manufacturing problems of PVC).
I have hoops made of all these products, but the one that I have the most hope for is bamboo.
It’s very flexible when it is young and after it’s just been cut. When it dries, it becomes stiff and holds its shape. Which means… it’s not just for teepee trellises any more!
Here’s how to make bamboo hoops:
1. Find a friend with a stand of bamboo , and cut a half-dozen culms that are 1/2 to 1 inch in diameter and 12 to 15 feet long. Look for pieces that are lighter-colored than the more mature, larger pieces. These will be more flexible. I’ve found bamboo to be more flexible in the spring, and have learned that it can’t be bent into extreme arcs. If you bend it too far or it’s too woody, it will break with a loud crack along the top of the hoop.
2. Strip off all the leaves. A sharp pair of pruners helps with this job. It’s OK to leave the stubs to be smoothed off after the bamboo has dried.
3. Cut off the very flexible top 2-3 feet. This part would bend or break quickly when used.
4. Cut off the stiff bottom end to make a stick about 8 feet long.
5. Stick one end into the ground 6-12 inches, along the inside edge of a raised bed that is 3-4 feet across. This works best with a raised bed made of wood or some other rigid structure, because the bamboo will exert force against it.
6. Grasp the other end with both hands and pull it slowly down into a hoop shape to the opposite edge of the raised bed, then also plunge it into the ground 6-12 inches. Make sure it is securely in place before you let go, because if it’s not, it could spring back out and whack you. Please try to avoid this; trust me, it’s painful.
If you don’t have a raised bed, an alternative method is to bend the bamboo between two other hard surfaces, such as a wall and a set of steps. Pick an out-of-the-way location, because it will have to remain there until it dries.
7. Repeat this process until you have as many hoops as you’ll need to cover your bed, spaced 12 to 18 inches apart. If you need extra help to hold the hoops into their shape, bind them tightly with plastic zip ties, which can be cut away when the bamboo is dry.
8. After a few weeks it will start to dry and you can use it, but it will take 2-3 months for it to completely dry and turn from green to brown. Once it’s dry, it will retain its hoop shape.
9. Trim off the rough edges of the leaf stubs at each node so there are no sharp edges that would rip the plastic. After it’s dry, you can smooth them with a file or sandpaper if necessary.
An 8 foot piece of bamboo placed into a raised bed that’s 4 feet across will yield a hoop that’s about 20 inches high. That’s plenty high for growing salad greens or root crops, or for getting your peppers and tomatoes off to a good start.
The hoops will last 1-2 years if the ends are in contact with the ground, longer if they are above the ground and tied to stakes.
This project will definitely continue to be an experiment, and I’ll update this post with any refinements to my technique. If you have tips, please drop me a note or a photo to share!