Monday, February 9, 2009

Hoophouse Growing Reflections

I recently gave a talk for Project Grow about Growing in a Hoophouse, which was great fun. There were so many interested participants who also offered so much of their own knowledge and experience that I felt I learned a whole load of new information, too. The following post is one I wrote for the Project Grow blog, but thought it would be good to add here, too.

We are working on getting the documents up from Saturday's class. (We're experiencing some technical difficulties, but they will hopefully be remedied shortly.) Drop us a note at Project Grow and we'll find a way to get you the information you want.

The Resource List offers links to various websites, recommended reading, and a short list of blogs. Suggested additions to this Resource List would be more than welcome. One great idea from an attendee on Saturday for those who don't wish to fool around with creating their own was, I believe, the Greenhouse Mega Store.

The actual presentation offers mostly pointers, guidelines, and some lessons learned. Questions on Saturday centered mostly around ventilating - how long and at what temperature; building materials - PVC or no PVC; site selection and ordinances on building such a structure.

Ventilating the hoophouse is pivotal. Built to help retain heat and protect plants inside from cold weather, temperatures inside can easily and quickly run high. Left unattended a little too long in the early days of having one, our temperatures reached into the low hundreds. The transition from hot to cold could prove a bit much for plants - cooking then freezing which would wilt me, I must confess - and needs to be mediated a bit. A good rule to follow would be that if interior temperatures run above 90 degrees it's time to ventilate. To keep some of that great heat it's best to close it up again an hour or so before sunset.

Some suggestions about heat included having barrels of water inside painted black. These would act as a heat sink during the day and slowly release their accumulated warmth through the night. They could also be used as a water source for plants. Others suggested building the hoophouse against another structure with a south-facing wall such as a garage, shed, or fence.

Building Materials
We used PVC pipes and translucent plastic, but not without some trepidation. As we learn more about how such plastic is not the best for us, some attendees asked about alternative materials such as electric conduit. Our neighbors at Frog Holler made theirs out of cedar milled from their land to create one of the prettiest hoophouses one could imagine. (Theirs also succumbed, unfortunately, to the snows this winter.) No structure is infallible, but it pays to research the design as well as the design materials to see what you think will work best for what you want.

Our criteria were that it be relatively easy (we're not handy people), inexpensive (the whole point of building this was to keep eating our own food as much as possible), and temporary (we wanted to switch it to other beds or take it completely out as desired.)

Site Selection and Ornery Ordinances
We built ours on existing garden beds with relatively established crops we wanted to keep growing and that were cold tolerant, i.e. kale, broccoli, parsley, beets, swiss chard, etc. The spot already received a fair amount of sun and would continue to do so over the coming chilly months. Remember the sun swings lower in the sky, so trees or buildings that might not cause a shade issue in the summer may as winter approaches.

We also live in the country so we have relative freedom to do what we like despite the opinions of our neighbors. Folks in the city may not have this luxury, and it might be a good idea to chat with your neighbor who shares the view of your backyard. (An offer of vegetables, soup or other meals might prove the winning ticket in this instance. Maybe even space to grow something!) You may also run up again rules of neighborhood associations or the city itself. As someone at the recent Local Food Summit suggested, a touch of green civil disobedience may be interesting and generate interesting conversation for these long winter months.

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