Retrospective – building our high tunnel hoop house

Starting in January, we covered the construction site with a tarp to kill the grass.

The site was then rototilled…

We built the hoophouse roughly according to the instructions provided by Johnny’s Seeds. The hoops for the high tunnel are just top rails for chain link fence (1 3/8″, available at Lowes). We bent these using a homemade pipe bender, fashioned by cutting a 7′ radius arc into a 2″x10″ board.

The hoops were mounted on posts driven into the ground, and then covered with 6 mil UV-resistant green house poly film.

The glacier left us presents.

Part of the job of preparing beds in our newly constructed high tunnel hoop house is removing more than a few large rocks of varying size lurking just beneath the surface of the soil..  I pulled this one out last night.  It is, by no means, not the largest rock I have extracted.

A glacier really did a number on our Skykomish river valley during the last ice age. Our top soil, ranging in depth from 1′ to 2′ in thickness, sits on top of a concrete-like layer of sand and gravel compressed by the huge pressure of the passing glacier. Sitting on top of this compressed layer are rocks ranging in size from soft ball size to automobile size.

My high tunnel

I am building a high tunnel greenhouse this summer. Only the back wall remains to be completed, as shown below.

The structure is 13′ by 64′, with the hoops 7.5′ tall at the center. I have been roughly following the plans described in this pdf from Johnny’s Seeds. The beauty of this approach is that the material with the most expensive shipping costs, the hoops, can obtained locally. The hoops are formed by bending and joining two chain link fence top rails, which are sold by local Lowes and Home Depot stores.  Cheapskate that I am, I did not buy the hoop bender device sold by Johnny’s, but I created my own bender by cutting a 7′ radius arc into a piece of 2×10 lumber.  Here is the bender I created, mounted on the wall of my tractor shed.

I deviated from the pdf plans by using 3/4″ EMT conduit for the center purlin, and simply linked this to the hoops with carriage bolts. The Johnny’s plans use more fence top rails and link these to the hoops with pricey adapter brackets. My approach saves some $ and still produces a very solid structure.  Johnny’s provides plans for shorter (6′) and taller  (8′) versionsof the hoop house.  I split the difference.  I pounded 4′ sections of chain link fence post material 2′ into the ground, and inserted the hoop rails about 1′ into the projecting portion of the pipes, giving me hoops that were about 7.5′ at the center.

In preparation for building the greenhouse, I covered the footprint with a tarp for 4 months, killing the grass and weeds, or at least weakening them. I then covered with a half ton of horse manure and rototilled.  After skinning the green house, with 6 mil poly, I redug the beds to a depth of about 14-16″ using a broadfork (dimly visible at the far end of the high tunnel) , and worked in another quarter ton of composted horse manure along with 10 lbs of lime and 10 lbs of bone meal. The soil is still very rough and lacking tilth, but tilth will come with time and love

As you can see, I have already transplanted a row with tomatoes, with a few melon plants at the end of the row. I am creating slightly raised beds. The beds are 30″ wide, with 10″ paths. I am putting two lines of rip tape for drip irrigation in each bed, but these are not yet connected to the requisite filter and pressure regulator.  That will be accomplished this weekend. The tomatoes will be trained to climb twine suspended from the hoops above (images coming soon). The two rows at the side of the greenhouse will be planted with lettuce, spinach, kale and brassicas, hopefully producing crops that will last late into the winter.

Low tunnels

This year I am introducing a new method for making low tunnels.  6′ lengths of 3/4″ poly tubing are threaded onto lengths of bamboo.

The bamboo is inserted in the bed to create an arc.  These are linked at the centerline with a baling twine, and the hoops are then covered with poly film.

Greenhouse heated bench

Here is my new cable-heated bench for getting my tomato starts off to a strong start. 100′ of heating cable on a 3×12′ bench.  An Inkbird C206 thermostat controls Redi-heat 8554 cable.

[Update 4/5/2017] Sadly, the heating cables stopped heating after only one month in use. The thermostat continues to work well, so it now powers two 150W heat lamps.

bench

bench dirt 2

Too soon to think about Spring planting?

New varieties for 2017 planting – I just ordered these from Tomatofest.

1884
Alaskan Fancy
Amy’s Apricot
Aurora
Black Zebra
Dicoff’s Yellow
Full Flavored Paste
Jaffa
Josephine Carter
Malinowski
Matina
Milano Plum
Pink Grapefruit
Ten Fingers of Naples