Sunday, February 17, 2013

Hoop house heaven! (again)

Often people want to know more about what its like to be 'on the farm' on a daily basis, so I thought I might make an effort to share some of my activities, both and good and bad.

Today was a 'good' day - I got to play in the dirt!

Back in September, I found myself without anything important to do. I was confused, wandering around but unable to find a suitable project. I was as shocked to say the least! 

The roof is polycarbonite.
South face of barn.
So about 7 days before Hurricane Sandy hit, I decided to build a greenhouse. (Of course, what else would you want to do as a massive Hurricane was barreling down on you).

I must admit that during my 50 years, there isn't really all that much I have denied myself, but a heated greenhouse was one of them. 

Still, I could never find justification for such a hedonistic, environmentally-unfriendly, fossil-fuel sucking, money pit of a project.

However, on the farm, things had suddenly changed. I had plants to start for the veggie garden and previous years' jury-rigged hothouses had been pretty inadequate. ('I'll never do THIS again!' I grumbled last year.)

I finally had my justification and my evil plan was sprouted! I would have my heated greenhouse, finally!

Of course, there was no money and I work full-time off the farm, but I did have some free time, so what the hay.

This space is a lounge area for the interns.
I built the heated cool greenhouse attached to the workroom of the barn, on the south facing facade, where I can take advantage of the protection the barn provides from prevailing, cold winds. The concrete floor, part of the barnyard, serves as a heat sink and provides a good surface to work on.

Access is through a sliding barn-type door off the workroom.

What a luxury! I just don't know how I've managed so long without one!

I built the frame out of pressure treated wood. Roofing is twin-wall polycarbonate and the windows are inexpensive stock windows from Lowes. They're all vinyl, so are rotproof, energy efficient, and don't need paint. I considered triple or quad wall polycarbonate for the roof but decided against it when I saw how much light is lost with the improved energy efficiency of the thicker poly.

The hip walls are super-insulated and clad in galvanized roofing material. I decided against glass in the lower walls because its the least useful space in any greenhosue due to the lower temps near the ground. The space under the tables provide a dry space to store supplies.

The shed design for the roofline allowed me to add a second tier of windows on one side. This will allow passive venting of hot air along the high side of the greenhouse with very good cross-ventilation when needed.

All in all, the materials cost about $6500, which includes about $1200 for the galvanized tables. The table surfaces are polymax material available as an option on these Farmtek greenhouse tables. I like the fact that they keep my supplies dry underneath and provide a smooth surface on which to work, but they aren't as thick as I would have liked and bow somewhat in the middle, which causes some pooling of water.

Farmtek and I have a love-hate relationship. In my experience, their quality is not always that great, but what can you expect considering their generally low prices. I buy from them with caution ;)

When I say 'cool heated greenhouse', I mean that supplement heat is provided, but it is far from tropical. Nighttime temps can go as low as 40 degrees. I provide heat mats which have been shown to improve germination but also, cold tolerance, even for heat-loving plants like tomatoes.

This is where my tomatoes for the summer garden are started. I already have tomatoes and basil going, as well as lettuce plugs for the hoophouse to fill empty spaces as they come up.

Here you can see some of our lettuce starts alongside a close up of our spinach bed. The wire hoops allow us to cover the more sensitive beds with agribond, also known as row cover material.

Agribond/row cover material is an awesome product that provides a 'blanket' for plants both inside and outside the hoophouse. It protects the plants from frost, heavy snow, and the like, while retaining heat and creating a micro-climate for the plants. 

This is a double layered system inside the hoophouse which was originally used in Europe on a very large scale to provide local food for large cities like Paris and London. The prospect of transporting food over large distances was not an option in the 18th, 19th, and early 20th Centuries. This was more or less how it was done up until the mid-20th Century.

Current crops include spinach, swiss chard, carrots, lettuce, beets, and kale. And what a crop it is! These plants thrive in the cool, bright light!
Watering on a grey day.
5 different varieties of lettuce.
Lancinato kale thrives

Weed pressure tends to be very low in the hoophouse. We've had some trouble with fungal infections which I imagine are exacerbated by the row cover material. Better cross-ventilation would probably help, but its been too cold most days to open the greenhouse doors and we won't use fans for this project.

One of my goals for the unheated or cold greenhouse/hoophouse was to not use any electricity for heat or ventilation. I wanted this hoophouse to only use passive solar energy, to show how much can be grown with only passive inputs.

We have pulled out probably about 10 tons of produce from this 30 by 90 foot hoophouse so far this winter, and I expect to pull out another 10 before we till everything in and plant our summer crops. This year, our summer crops for the hoophouse will be peppers, tomatoes, and cucumbers.


  1. Kent as always an ispiration! Just a "little" hoop house from bordom! You are one of a kind!

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