Hoop House Ramblings

I wake up early. During the week I start the day before 4am, so on the weekends even 5:30 seems like sleeping in. This morning at said time it was all of -9 degrees. Even by mid afternoon the temps hadn’t really crossed zero yet, this is one mean cold snap! So of course I went to visit my spinach and bok choy.

By the time I got out there the sun was well past its zenith, and the current site of the Hoop House is shaded from about 2:30 on. Obviously this needs to be remedied for next year, but that is where I am. Pulling in with the kids, it was all of -1 with a bitter wind. The door to the house was frozen shut, and the entire interior was frosted over, further reducing solar gain. Interior temps felt balmy: despite the 80% shade were still in the low 20’s.

The Spinach had obviously taken a beating the night prior and was laying flat, but the mache, claytonia and bok choy looked no worse for wear. I am not overly concerned about the spinach as it has pulled through before. More interesting, despite the wicked cold, the soil still had not frozen!! Even better, last weeks highs in the 50’s had actually woken up the soil enough that I had dozens of new earthworm holes, some with visible castings. Apparently the heat and/or the 1/2″ layer of comfrey fronds I had laid down 3 months ago is doing the trick!

I certainly will not get a harvest before March, but I will have a the earliest greens harvest of my career.

Plans for next year:

  • Orient the Hoop House correctly
    • Currently shaded from 2-3pm on, and it is on a N-S axis. Both must change!
  • Use row covers for additional frost protection
  • Use heat sinks to store solar gain
    • The 5 gallon buckets I used this year just froze solid.
  • Use compost to generate BTU’s from December-January

Even still, this remains an exciting adventure and being able to run my hands through soil with the outside air temp at -1 is a real treat! Hoop Houses are a great option: this one cost under $500 in materials, is “portable” and only takes up 12×25′ in space making it versatile while still providing 200 sq feet of growing space.



11 Responses

  1. About the heat sink, do you have room for/could you get your hands on some biiiig barrels or plastic containers? Family friends of ours have a greenhouse that they used to passively heat by keeping big 55-gallon drums filled with water. The drums were painted black so they’d take on as much heat as possible.

    200 square feet of winter growing space sounds fantastic, even if you do need an ice pick to get inside!

  2. I had one black garbage can that did not freeze solid, though the ice is 8″ thick on top. I have found a virtually unlimited source of plastic 55 gallon barrels, following your thought and running with it: next year I could get about 10-15 barrels to line the north wall with, and then pack the area between them and the plastic with straw or something for insulation. If I double row them, this could also make a nice flat surface for spring seedlings…

  3. It may be a bit too much hard work, but I have read that installing sub-surface protection can work to improve internal temperatures. I think the idea is to extend a solid wall a metre or so vertically below or immediately adjacent to the outside walls. This prevents heat loss from within the structure via the soil, and also adds to the thermal mass that can absorb solar heat. I have only read of this – I cannot comment since our problem is not one of too much cold, but of too much heat – some of our vegies get grown in a shade house year round.
    On another topic, I am keenly following your 0.1 acre plans, and will probably weigh in at some time to compare notes once my own plans are a bit closer to being approved (by the good wife, who knows me well enough to know that I always start things without thinking them all the way through, and without any real concern about not completing them and leaving their evidence strewn from pillar to gatepost (literally)).

  4. Great stuff, Rob. I had a tunnel in my garden two years ago and it worked great–we had salad greens all year. It was even a little too hot and humid for the broccoli and Brussels sprouts.

    Have you read “Four Season Harvest” by Eliot Coleman? He’s bigtime organic farmer in Maine, uses cold frames inside hoop houses to grow through very cold winters–a kind of double insulation.

  5. Some interesting thoughts here Rob. Cold isn’t a problem I have right now so you have my sympathies.

  6. Bryan,

    Subsoil insulation does help, but my soil temps are significantly higher than my air temps right now, the trick is to either offer either better insulation through additional row covers, sore heat better through “sinks” or use supplemental heat from some renewable (and free) source like compost. Some friends of ours built a much more permanent structure and insulated the foundation down to 4′ and are loving the results!

    Ed, Coleman is a Master and I reference his books often. The choice of plants this year came straight from Four Season -without him I would never have even known about mache or claytonia.


  7. Very cool! We have a tiny yard but I have been looking at lean-to mini greenhouse structures or just bigger cold frames out in one area. We get shade there much of the afternoon too, without much flexibility in where it could go with this odd yard. Good to know it is possible even with that shorter sun orientation! 🙂

  8. Hi Rob
    I have a hoophouse too (although semantically I simply call it a greenhouse because nobody knows what a hoophouse or cold frame is), and I was wondering: do you have some ag cloth in there atop your greens? I have Reemay (Agribon, actually, #19) atop my beds, and my beds are raised, and I have been harvesting things since practically the day I planted the thing in October. I’m not bragging; I’m simply wondering is all…I just followed Coleman’s suggestions practically to the letter. (I’m on the other side of the lake from you so it’s a bit warmer here.) I haven’t gone in for hotbeds (manure, etc.) or going in for black-painted barrels or anything else silly that supposedly keeps thermal mass in there. I’m wondering if siting and raised beds are the key.

    Yours in the digging,

  9. El,
    I did not put anything on top of the beds this year, though next year will be a much more concerted attempt at 4 Season Growing. I don’t take your harvests as bragging -anyone who can eck out some produce after November in Zone 5 or further north is due some props.

    This has either been a horrible or fantastic year to start cold winter gardening. Less than 3 weeks after I planted we got a -4 degree cold front. Last year we only had one night below zero, this year we’ve had 4 separate super cold fronts, one staying for almost a week with nighttime lows well below zero. Next year I will start a month earlier (I didn’t get the go ahead until late in October) and will use more of Coleman’s and others learnings.


  10. I live in the midwest and had two cold frames that yielded early spring greens this past season. This fall we put up a hoop house and transplanted beets and chard from our veg garden. So far the sun does a terrific job of keeping the house warm however wondering if there might be any portable heat source anyone can recommend for the coldest parts of January and February. I used votive candles inside and rug coverings over my cold frames last winter and both seemed to help. I am scared that cold, cloudy days may cause damage to my plants this year in the hoop house. Any ideas?

  11. Row Covers work well to give you another 5 to 10 degrees of frost protection. If you have allot of nitrogen rich compost materials, you can setup hot piles throughout the house to provide some BTU’s, but as soon as they cool off you have to fire them up again.

    We typically see a week or three of sub zero temps here – my solution has been to plant varities (spinach, claytonia, and mache) that can take that kind of cold. Actually the spinach dies back, but regrows when the weather warms. I have no means of fighting that extreme cold without burning something in a heater.


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