
Easy season extension with a hoophouse
Another fall-themed post today! Over at the garden we’ve had our final workbee of the season, and have been steadily putting the garden to bed, taking care to improve the layout and soils to ensure next year will be even better than this once! The garden hasn’t gone completely to sleep yet though! Fall is a great time to grow a wide variety of salad greens, root vegetables and brassicas like broccoli and cauliflower. These crops can handle cold weather and some of them, like kale, actually taste better after a frost! There are a variety of techniques out there to allow you to grow these late season crops later in the year than you would expect, methods which are collectively known as season extension. Two common and simple techniques are cold-frames and hoophouses.
Cold frames are simple boxes often made from wood which are placed in a sunny spot and covered with clear plastic or glass. These work like a miniature greenhouse; although they are unheated they trap enough heat from the sun to serve as a place to start seedlings in early spring, or as a permanent home for late fall and early spring crops. We intend to include a cold frame in our garden next year, either buildling a cover from plastic and wood or recycling an old window frame, a simple and inexpensive option for building a coldframe yourself.
Last week, we installed a hoophouse in the garden, a simple and flexible structure that we hope will let us grow some leafy greens into December. Hoophouses are basically miniature plastic greenhouses and are also called “low tunnels” as they generally stand no more than 2 feet high. There are a variety of different ways to build hoophouses, techniques which provide varying stability and ease of transportation. Generally speaking, they are made of a few simple materials: thick plastic, flexible pvc piping and wooden framing or rebar. This creates a covered area which is easily accessible for watering and harvesting, but generates enough heat to grow vegetables for an additional month or more!
We decided to go with the rebar method as the materials are simple to transport and dissemble into small, easily stored pieces as opposed to

From Left: Plastic, rebar, zipties, pipes, radiator hose, hammer and saw
constructing a large wooden frame as a hoophouse base. Our required supplies were: 1/2 inch diameter rebar cut into 8 2 ft long pieces; 100 ft of 3/4 inch diameter pvc piping; 60 ft of 6mil plastic sheeting; 2 ft of radiator hose cut into 8 equal pieces and slit open lengthwise with an X-acto knife. All of these supplies can be purchased at a home depot or other building centre, but in a variety of different sections: construction for rebar, plumbing for pipe, and painting (around the tarps and drop sheets) for the plastic. You’ll also need some stones or bricks of any size to weigh down the hoophouse cover for security.

Cutting pvc pipe
To start, we decided on the area we wanted to cover. Building a hoophouse is something you can do with a great deal of measurement and premeditation, but we just eyeballed it and threw it together, and it worked out great. It is good to keep in mind, however, that your hoophouse will do best if you orient it east-west, that is the short sides facing to the east and west, the long sides facing north and south. This maximizes sun exposure, but if you have powerful winds, position the hoophouse however will best protect it from gusts.
Set out your area and drive in your first two pieces of rebar about 3 feet apart. This will be the location of the first hoop of your hoophouse. The remaining hoops will extend behind it, so drive in your rebar parallel to your first two rods, at a distance of no more than 3 feet apart.

Pipe bent over rebar
The rebar forms the base onto which you will slide pvc pipe, creating the 4 arches of the hoophouse. Cut the pvc piping using a handsaw or pipe cutters into 4 pieces of equal length that will give you arches about 2.5 feet high when stretched across the rebar. If you aren’t growing anything that gets tall, or if you want to save on piping, feel free to make it even shorter, but keep in mind that the lower part of the curve should provide enough space to grow in too. An additional piece of pipe the length of the entire hoophouse is also needed to provide stability.

Securing centre support
Bend your pipes over the pieces of rebar, and attach the longer piece along the centre of the arches using zip ties in order to provide additional support. The final step is to cut the plastic sheeting into a piece long enough to cover the entire structure with at least 10 inches of overhang on the soil. Drape it over your structure and put bricks or stones (or anything heavy that can stand up to the

Draping plastic over structure
elements) on top of the plastic overhang every couple of feet to prevent the plastic from blowing off in a heavy wind. The 1 inch radiator hose is used to clip the plastic around the piping near the top of the structure to help keep its shape and prevent wind damage. We used radiator hose because the neighbourhood hardware store didn’t have any 1 inch pvc piping, but I wouldn’t recommend it, it’s more expensive and too flexible, ours keeps falling

Finished structure with stones and clips on (place your clips a little higher though!
off. I’m going to get some one inch pvc piping and use it to make 4 clips for each hoop, its increased rigidity should make the structure much more secure!

Lettuce growing under hoophouse!
That’s it! You’ve got your hoophouse! Simply fold up the plastic cover as needed for watering or harvesting, and otherwise leave it down to trap heat and allow your garden to produce greens into the winter. Make sure to fill the area under your hoophouse with plants as it is the transpiration from their leaves that really helps the plants to stay warm and keeps the soil moist.
For more info on building and using hoophouses check out:
Instructions to build a much larger and more permanent hoophouse here
Video: Building the White House winter garden here
Video: Harvesting from White House hoophouses here
Videos: Different hoophouse building approaches here