best plastic film for hoop houses
We want to grow veges like lettuce and arugula but also some overwintering plants like broccoli in hoop houses in Benton County. We've never done this. We understand there is clear, 55% white and white film of various thicknesses. One site cautions against clear because plants like broccoli go dormant. Do we need to keep overwintering plants like broccoli and cauli in separate houses? What color, if any, should we use? What thickness plastic? Any thoughts on hoop house designs not found on most internet sites?
Benton County Oregon
Hi there. After reading your question I am not sure whether you mean a greenhouse style hoop house or a row cover that you will build over a raised vegetable bed or in ground row of vegetables. I read a lot of recommendations from extension publications all around the country and they suggested thickness of plastic was between 4-6 millimeters. This was for a greenhouse type structure and assumed a double layer of plastic with the outer thickness being 4-6 millimeters. Thicker plastic is a bit tougher to work with but is also more durable. There are plastics that you can purchase that filter sun rays and if you are worried about your dormant broccoli plants perhaps you should discuss this with a vendor either on line or a local greenhouse store and ask for a recommendation based on the application you are thinking of. I have a hoop style greenhouse in my backyard and after several discussions with the place I purchased from I selected two plastics for my double walled structure that have worked exactly how I wanted them to. My structure is used for propagation and starting of seeds. The outer layer is thicker and slightly filters sunlight while the inside layer is has an attribute that prevents condensation from forming so I don’t get rained on inside. You can tailor the plastic to your needs and wallet. As for the design of your structure it again depends on the size and use. I also have raised beds that my husband attached PVC pipe hoops to and we can cover them with plastic or bird netting depending on what I am growing in the bed. We have found that having a straight piece of PVC pipe running the length of the bed and attached to the hoops at the top helps stabilize the whole thing. We use cable ties to do this and while they need replacing periodically they also make it easier to take the structure down and move it to another bed. It works for us and withstands our summer evening winds here in Benton County. We went into a big box store and purchased a thicker clear plastic for use with these beds and have not had any issues, but we have not over wintered the plants you are talking about. You could also go to a greenhouse type store or website and purchase the plastic for this type of structure. I would also like to inform you about a class on this subject that is being taught by our Linn/Benton Home Horticulture agent, Brooke Edmunds, on October 30 from 12-1 pm. The class is “Season Extension with Low Tunnels & Row Covers”. Learn how to extend your gardening season with low tunnels and row covers. This is a hands-on class and will include making hoops from conduit using a Quick Hoop Bender and installing it in a raised bed. A limited number of kits will be available for sale after the class. Location is The Veterans Garden at Linn Benton Community College (located behind the Luckiamute building on the Albany campus). There is no fee to attend the class and no registration is required. If you require more information on this class, please call the Benton County Extension Office 541-766-6750 between 8 a.m. and 5 p.m. on weekdays. I have also attached a couple of links that provide information on fall/winter vegetable gardening and how to build a raised bed with a cloche over the top of it. All are OSU Extension Publications.
Growing Your Own. EM 9027 dated 2011. https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9027.pdf
Fall and Winter Vegetable Gardening in the Pacific Northwest. PNW 548
How to build your own raised-bed cloche. EC 1627