Building a Hoop House – An affordable way to protect your plants and extend your growing season
Today’s blog post comes to us from a customer who got very creative with his growing structure. Get ready to learn how Carlos from Connecticut constructed a hoop house to cover his garden.
Why I needed a hoop house
Last year I purchased two raised bed kits from Growers Supply to grow heirloom tomatoes, Japanese cucumbers and eggplants and other Asian vegetables for my wife. Compared to our previous in-ground garden, the raised bed produced a better yield and tastier vegetables. However, we weren’t the only ones that enjoyed the greater harvest – squirrels, birds, rabbits and other critters took delight in this “salad bar.” This year as we were seed starting I began to consider solutions to keep them out of our raised bed garden.
I considered placing a small fence around the garden. While this would help to deter rabbits, squirrels would laugh at our feeble attempt to thwart them. The garden fence would also be ineffective to aerial attacks from birds. Placing bird netting around the raised bed was my second choice and would have worked well. Using flexible tree stakes or galvanized pipes as posts would have solved most of the thievery. As I considered this solution, I became interested in solving another past problem: extending the growing season. Extending our growing season has always been a dream of mine. My wife felt that a greenhouse or high tunnel would simply overwhelm our small suburban yard. Looking through the many products on Growers Supply’s website, I came across their Mini Cold Frames. These units are raised beds with metal rounded pipes that allow you to cover it with greenhouse film. They seemed ideal and were available in many sizes. However, since I already had the base part with my two raised beds, I only needed the metal pipes and greenhouse film.
Protecting your plants with a hoop house
Searching online, I found many articles and videos for building a hoop house. A hoop house is simply a structure with rounded pipe that is covered by some material. The covering helps to keep the heat inside and also protects the plants from garden pests. In the majority of online articles, the authors suggest using PVC piping. While this may be the lowest cost solution for forming the frame of the hoop house, I don’t recommend it. For a viable long-term solution that will allow you to reuse your greenhouse film and to ensure the safety of your food, you either need to use another material for the frame or somehow separate the PVC pipe from the plastic film. For my hoop house, I decided to use conduit. Although I don’t plan to grow during the winter, conduit provides a much more stable frame so if we were to have an early freak snow storm, as we did in New England in 2012, my structure will be safe.
The design for my hoop house was inspired by the previously mentioned Mini Cold Frame. I also used the building plans from Growers Supply’s ClearSpanTM Round Cold Frame, which I highly recommend. You’ll receive all the pipe, fittings and connectors and with some models, the greenhouse film. The instructions are very clear and provide a great step-by-step guide to building a hoop house. I already had several key components and I also enjoy building things on my own, so it was a great choice for my needs.
Initial steps for constructing a hoop house
The first component to consider in the hoop house is its base. In my project, I utilized my raised bed kits’ recycled plastic lumber. This is ideal because the material will last 50 years and I’ll never need to paint it. I re-assembled my two raised bed kits into one two-tier unit and made sure it was squared. Inside the raised bed, I dug about 1-1/2 feet down into the soil. I placed wire mesh at the bottom, which helps to keep the burrowing critters out. I used a post driver to pound in 2-foot ground posts in each corner of the raised bed. Having decided how many pipe rafters I would need for my hoop house, I also placed two ground posts for each of the five rafters. The amount of rafters in your hoop house will depend on whether you plan to grow into the winter, your location and how stable you need the structure to be. Ground posts are a must unless you want your hoop house to fly into the next county. I used heavy-duty pipe straps to secure the ground posts to the raised bed kits.
Once the ground posts were secured to the raised bed kit’s base, I proceeded to fill it with soil. I used a combination of Wonder Soil® Reground, Perlite and some local soil. The perlite helps grow healthier plants and reduces the amount of watering required.
Bending hoop house pipe
The greatest challenge in building a hoop house is the frame construction. No doubt this is one of the reasons why so many people decide to use PVC or plastic pipes. That shouldn’t deter you from using metal for your frame. You can use a hydraulic pipe bending machine or a small portable pipe bending device to bend the pipe frame. If you don’t have access to this machinery, you can attempt to bend the pipe yourself. However, you won’t be able to use heavy-gauge pipe, as the strength required to bend the pipe will be too much. Your attempts will also lead to pipes that have a crease. For my hoop house, I used half-inch galvanized pipes that I purchased locally. I found this to be the optimal size for bending by hand, while providing a sturdy structure. This pipe also easily slid into my stronger and larger pipe which I purchased from Growers Supply.
The first step before bending your pipe is to calculate the diameter of the bend. A quick search online will show you calculators where you can enter the span (width) and the desired height of your hoop house. With calculations in hand, I placed a large wood board and drew a circle that would I would use as a guide for the bend. Use heavy-duty nails or screws every few inches on this guide circle. In the picture below, you can see that my screws form an arch. I placed a 2 x 4 block to the left of my guide and slid the metal pipe between the block and the screws. The block acts as a counter as you slowly pull the pipe towards your guide circle. My first two attempts ended with pipes with kinks. The key is to go slow and use a steady amount of force. It’s natural for metal to want to spring back to its original form, so once you’re done with the bend you may need to hand bend it a tad more by using your body and the ground. This can be difficult and should be done carefully. I recommend you search online for videos on this pipe bending method.
Constructing hoop house rafters
With my ground posts secured to the raised bed frame, I slid in heavy-duty conduit for the side pipes. I purchased the pipe with a swaged end which allowed my smaller rafter to slide in perfectly. Each side pipe was connected to the ground post with tek screws. Although tek screws are self drilling, I found that creating small pilot holes made the process easier. Next, I slid the bended rafter into the side posts. Remember to use the swaged ends at the top so your smaller rafter pipe is nice and snug. You’ll want to use tek screws again to secure the rafter to the side pipes and be sure to keep all screws on the inside of the hoop house. If you place the screws on the outside, you’ll tear your cover. Next, I installed the remaining rafters. As I mentioned, you’ll determine the number of rafters based on your location and specific needs.
Once the rafters were in place, I had a structure that I could cover with greenhouse film or shade cloth. However, I wanted a little extra stability, so I added a top support pipe. I used various connectors and tek screws to secure the roof pipe to each rafter. I placed the roof pipe on the inside so that any covering would easily slide over. I noticed that the roof pipe added a greater amount of stability to my hoop house. It also allows me to use trellising connectors and hooks for growing my tomatoes.
Improving the hoop house
I plan to cover my hoop house with shade cloth from Growers Supply during the spring and summer. I may consider greenhouse film towards the end of the season. With that in mind, I moved on to the next step in my hoop house project. I installed 1” recycled plastic lumber down my hoop house with tek screws at the height where the side pipe meets the rafter. While this provides even greater stability for my hoop house, the main reason was for my aluminum channels. These were installed over the recycled plastic lumber. I could have installed the channels directly onto the metal frame but using the recycled plastic lumber seemed like a better solution and, as I mentioned, the added durability was an extra benefit.
The shade cloth or greenhouse film will slide over the structure and stretch to the bottom, where the raised bed kit is. I will then install metal spring wire into the aluminum channels. This method allows the shade cloth or greenhouse film to stay firmly in place over the hoop house. I can also lift the sides to collect the vegetables or keep the ends up to allow for ventilation. I will install aluminum channels at the bottom of the hoop house over the raised bed to help secure it at the bottom as well.
Hoop House Irrigation
By covering the hoop house with shade cloth, I am able to use rain water for irrigation while keeping out the neighborhood critters. The shade cloth will also help to reduce the amount of watering that will be required. That said, I still wanted an easy method to irrigate the vegetables. I purchased two Soaker Hoses from Growers Supply and connected them to a Y-adapter. The Y-adapter allows you to stop the flow to each Soaker Hose, so it functions as a two-zone irrigation system. This irrigation method saves labor time (I can harvest while I water) and is inexpensive. I’m planning, however, to switch to a drip irrigation system next season. It seems to be more efficient and effective.
Growing in a Hoop House
Our plants are coming in nicely and we are very satisfied. I haven’t installed the shade cloth yet as funds were diverted to constructing a Japanese garden near the hoop house. Constructing a hoop house was a lot of fun. There were steps which I could most likely improve on and perhaps purchasing a complete cold frame or hobby greenhouse would have been a smarter investment. Still, I like working with my hands so I’m very excited to show off the hoop house to my neighbors, many of whom expect me to start attending my town farmer’s market!
About Carlos: Originally from Brazil, Carlos was introduced to hoop houses and greenhouse environmental controls while living in Japan for 15 years. As a native Brazilian, he is very passionate about his coffee and loves fresh, locally grown vegetables and cheeses. In addition to many American native vegetables, Carlos grows many Japanese vegetables and herbs, such as okura, shiso, and mitsuba. When not tending his own garden, he enjoys visiting farmers markets such as the Coventry Farmers Market.