Hoops Built with Electrical Conduit Pipes

Courtesy of Brenda S., Thompson Street Farm, Glastonbury CT

Electrical conduit pipes work great for hoops. That’s all we use on our beds, and they survived Connecticut’s “Big Snow” last year. We used metal brackets and bolted them to the outside of bed and then used zip ties to hold the cross pipes together. Worked like a charm. They can also be pushed into the ground if you don’t have boxed beds.

We found the pipes at our local Home Depot for 0.95 each for 3/4 inch pipes – which is cheaper and more flexible than PVC pipes. The electrical conduit pipes are grey in color and in the same isle as the zip ties. At least that’s where they are in our store. The other place I’ve found them is in the plumbing aisle with the rest of the PVC pipes. Just remember you want the grey pipes not white.

Greenhouse Construction

Courtesy of Brenda S., Thompson Street Farm, Glastonbury CT
*We built our 14 x 24 greenhouse last year and here are some books that helped us. Because of my  husband’s limited knowledge and experience in building structures, we needed a very simple design. I ended up buying the basic frame kit without all the bells and whistles from Farm Tek (www.farmtek.com). I think the total cost was around $1,000, which included the plastic and hardware. Could we have done it cheaper? Probably but  again, my husband was unsure of his skills. In addition to the kit, I also
researched books and designs and found some books that were helpful.

Books I recommend:

• The Winter Harvest and The Four Season Harvest – Eliot Coleman. He lacks some of the details we needed to construct a greenhouse. Having said that, I loved his idea of using plastic electrical conduit pipes for quick hoops and it works well. These are different from the white PVC pipes they are grey in color and very flexible. We found ¾ inch pipes worked well. Eliot recommends ½ inch to ¾ inch pipes depending on what you are using them for. They’re cheap and hold up well in Connecticut winters. I paid 0.95 per pipe at Home Depot.

• The Polytunnel Handbook by Andy McKee & Mark Gatter. They are from the UK and have great ideas for greenhouse layout and making quick doors.

• The Hoophouse Handbook: Growing Produce and Flowers in Hoophouses and High Tunnels by Lynn Byczynski. This book is not long. I liked the drawings on the construction and we were able to adapt somethings to our project.

Between these resources, and what I found online, we constructed a beautiful green house that survived the big snow of 2010. Now I hope it survives Hurricane Irene this weekend. Yikes!

Use the Mantis for Tilling Raised Beds

Courtesy of James K., Virtually Green, San Francisco, CA

It’s still possible to rototill in raised beds if you use an electric tiller like the Mantis. Rototillers are major labor savers. I have one that I’ve used in beds for some years. Incredible torque. Good depth: up to 10″, though with a limiter I usually use it at
just a few inches depth for prepping beds for replanting. A set of simple L-shaped brackets bolted to the tiller tine shield front, back and sides can help prevent the tiller tines from gouging the raised bed frame sides or ends. The tiller is light too: I carry it one-handed over my shoulder.

DIY Coolbot Walk-in Cooler Tips

Courtesy of Jame K., Virtually Green, San Francisco, CA

Here’s a few quick thoughts about walkin cooler design, largely based on what my appropriate technology group used to recommend for village small-scale DIY walkin cooler systems.  We didn’t have the Coolbot at the time though:  it’s a great alternative to commercial refrigeration units.

Here’s a link to a Canada Plan Service document that lays out some of the basics for designing and building a walkin cooler.


The Coolbot retrofit of window air conditioners is a reliable solution, but do follow the Coolbot suggestions for the best air conditioner unit.  I know someone who went cheap and regretted it immediately.  I also recommend that you get two air conditioners rather than one, so you have redundancy in this critical component of the walkin cooler.  You really don’t want to find yourself with a failed air conditioner and a cooler full of spoiled produce.  If one of the units goes down the other can pick up the extra load until you can replace the failed unit.

Another thing.  Use a strip door to keep cool air in when you’re entering and exiting the cooler.  These are thick wide plastic strips that hang vertically from the top of the door to the floor and that overlap each other horizontally.  You push through them to enter and exit.  These can radically reduce the loss of cool air when moving quantities of produce in and out.

The size of a walkin cooler is based upon peak use, in other words the moments in the harvest cycle when you have the most produce needing cool storage.  Use the dimensions of your standard sizes of storage containers:  bins, boxes, tubs, etc.  If you’re doing the routine crop planning for SPIN beds then you should be able to estimate the maximum volume of your various harvested crops needing container storage in your walkin cooler during your harvest weeks.  Leaving 50% of the interior volume for aisles and air circulation is a good rule of thumb, which can also in emergencies temporarily handle extra produce volume if needed.

You’ll likely be using pallets or shelves for your containers, so remember to leave room for maneuvering dollies and lift-trucks in and out of the walkin cooler.  Shelves that can be adapted to different dimension containers allow you to flexibly respond to changes in the quantities of your harvests.  Also with shelves remember the work safety, ergonomics and back strain issues of lifting containers on and off high shelves.

You need to have the air inside the cooler circulating freely to avoid hot or cold spots or major differences in humidity in the horizontal and vertical volume of the cooler. Set the Coolbot air conditioners to optimize their effects on air circulation.

One thing you don’t want inside a walkin cooler is condensation problems, which can lead to mold and mildew that can affect produce quality.  You want high humidity to avoid dessication and wilting of produce, but not so high that water condenses on surfaces.  Mount a couple digital dual humidity/temperature meters inside your walkin cooler to monitor humidity and temperature at different horizontal and vertical locations.  You can use these to monitor and better calibrate the performance of your air conditioners as well.  I recommend buying ones with NIST certification to ensure that they will perform as advertised and also to satisfy any food safety regs or or insurance concerning produce storage.  Here’s an example of what I have in mind:  http://www.calright.com/products/prod_id/1794/


Water Meters to Track Usage

Courtesy of James K., Virtually Green, San Francisco, CA

If part of the deal for using someone’s property in your farming operation is paying for water, here is a source for water meters that you can select from to track your usage.


DIY High Tunnels

Courtesy of James K., Virtually Green, San Francisco, CA

A good source of practical ag info about high tunnels is the organic.kysu website page: http://organic.kysu.edu/CurrentProjects.shtml

It covers a lot of things of interest to SPIN farmers, including info about high tunnel construction, operation, energy efficiency, pest control, etc.

By the way, their peaked high tunnel design helps reduce problems with snow loading, as well as with condensation drip from the interior apex curve of half-hemisphere shaped high tunnels.

Their high tunnel design is 30′ x 40′ but can scale.

My friend Mike Bomford leads much of the research and field extension work of the KYSU sustainable ag program.

For those of you considering building high tunnels that are large and to last for a good number of seasons you should consider making your high tunnel out of steel pipe. There are a number of good steel pipe hoop bending tools out there that make the job easy and quick. You end up with a strong greenhouse that has the structural strength to handle attachment of interior fans, shades and lights (within reason).

You might modify any high tunnel design to bend half hoops instead of full hoops, with the last couple feet of each half hoop being straight to attach to a ridge beam and create a peaked roof. A peaked roof also makes it easier to build in ceiling vents if you need the ventilation in hot weather.

You might also consider straight sides and straight roof, using the pipe bender just to bend the wall- roof elbow (at the top of the sides and bottom of the roof): this increases the interior greenhouse air volume a bit and makes the interior edges of your planting area a bit easier to work. Here’s a couple high tunnel hoop bending tool sites: