Winter Greenhouse Construction

The concept for our greenhouse originates with Carol Ford’s book “The Northlands Winter Greenhouse Manual“.  We also incorporated some designs from Paradox Farm.  I highly recommend the book if you are interested in building a deep winter greenhouse

We started with some excavating and sinking posts into the ground.

Digging post holes
Digging post holes, Sept 1st

The greenhouse is attached to our wood shed and you can see the boiler pipes coming out the side of the shed.  We could not go deeper in the ground without moving the wood boiler pipes.

Dirt Work
Dirt Work, Sept 3rd 2015

We boxed in the area that will hold the thermal mass (rocks).  The bottom layer of our thermal mass is salvaged concrete pieces from an old silo.  This ended up working well since we were able to drive on it with our bobcat without causing ruts in the dirt.

Rock bed prep
Rock bed prep, Sept 4th 2015

We lined the inside of the rock bed with insulation and on the outside of the rock bed we added insulation at a 45 degree angle.  The drain tile is perforated and is meant to channel hot air through the rock bed.

Drain Tile In Place
Drain Tile and Insulation In Place, Sept 4th 2015

We were able to use the bobcat to move the rock into place.  We used 1.5″ washed rock.  The bobcat saved hours of work!  We used bracing to keep the posts from moving while the rocks were being added.  We ended up with about 14″ of rock on top of the concrete from the silo.

Rocks in the bed, Sept 4th 2015

All the rocks are finally in place and we closed up the perimeter.  The black pipe sticking up will eventually tie in with a pipe collecting hot air in the peak of the greenhouse.

Rock Bed Complete
Completed rock bed, Sept 4th 2015

We covered the rock with landscape fabric and then added dirt to finish the floor.  Now we are ready to start on the walls.

Dirt Floor
Dirt Floor, Sept 5th 2015

The first wall to go up was against the wood shed.  We used 2X6 lumber to build a 12′ wall.  Part of the reason for the 2X6 construction was to facilitate using wall insulation that we already had on hand.  We have posts going up to support the peak of the greenhouse which is at 14′.

First Wall
First Wall Up, Sept 5th 2015

It was really fun (NOT) adding the boards that run along the peak.  We placed two 2X10 boards running along the peak which support the roof.  The boards on the angle are 2X6 which will support the polycarbonate panels.

More walls
More walls, Sept 7th 2015

By the end of the day we had the roof framed and ready for metal sheeting.  We used 2X6 boards with 2X4 purlins on top.

Framing the roof
Framing the roof, Sept 7th 2015
Framing – different view

We extended the wood shed roof to make a walkway into the greenhouse that is sheltered.  We are ready to sheet the walls!

Roof is On
Roof is On, Sept 12th 2015

Enclosing the greenhouse with OSB.

Sheeting the walls
Sheeting the walls, Sept 12th 2015

We were able to re-purpose insulation from another building.  All the insulation in the walls is 6″ with 12″ in the ceiling.

Insulating the walls
Insulating the walls, Sept 19th, 2015

We decided to sheet the ceiling with white metal sheeting due to the moisture that we expect in the greenhouse.

Sheeting the ceiling
Sheeting the ceiling, Sept 19th

We special ordered the polycarbonate sheets so we could get 10mm 6X12 sheets.  We have 4 sheets on the long angled side.

Polycarbonate Goes Up
Polycarbonate Goes Up, Sept 21st 2015

Whew!  Twenty-one days ago this spot was fenced in for critters.

Winter Greenhouse January Update

The winter greenhouse is nearly 1/2 full of rain gutter planters that each sport a host of tasty greens.  It is quite glorious to fill a planter with soil and seeds while the weather outside is cold and snowy.  On a sunny day the greenhouse is a tropical paradise that defies the cold.

Greenhouse Planters
Greenhouse Planters

Growing has been slow during the grey days this December, but things have picked up with the sunny days in the last week.  We have been pleasantly surprised by the flavors of the baby greens where salad dressing seems out of place.

Baby Greens
Baby Greens

It has been fun learning the ropes in the greenhouse.  I’m about ready to start garden planning and thinking of what veggies I can start in the greenhouse.  Just think, it is only 53 days until March : – )

Greens in planter
Greens in planter

The Winter Greenhouse

Many of you already know that we are working on a deep winter greenhouse.  The shell of building has been completed.  Ryan has the ventilation fan hooked up to help cool off when it is sunny.  The passive solar heat system is completed.  We still need to install exterior siding and do something on the interior walls which are currently just plastic sheeting over insulation.  It still needs work, but is technically functional.  Here are some pictures.



Someday I will detail how we built the greenhouse, but not today : – )  Today I’m planning to setup some temperature monitoring in the greenhouse.  I have 10 temperature probes that I can use to track how the temperature is changing.  I also wrote a program that will record the temperatures so I can analyze it later.  Yes, I am a geek.


Here is a picture of my setup for testing the probes.  Each probe has a DS18B20 temperature chip enclosed in a stainless steel tip with a few feet of wire attached.  I bought a pack of 10 on Amazon for about $18 – what a deal!  The nice thing is that you chain all the probes together.  Each temperature chip has its own serial number so you can request the temp from each one.  It is really cool!

I found a sample program online for interacting with the chips using a DS9490R 1 Wire USB adapter.  I modified the program to capture the temperatures to a chart and then log the temperatures to a file everyday.  It seems to be working in my test environment so I’m going to put it in the greenhouse today.  I’ll post an update when I have it all working!

Sweet Potatoes

A few years ago I got it in my head to grow sweet potatoes.  I did some research and ended up planting an area about 10X10 with a dozen or so sweet potato slips.  I purchased the slips through some online garden catalog.  A couple weeks before planting we covered the entire bed with clear plastic and buried the edges.  When the slips finally arrived, we planted them by cutting X marks in the plastic.  Most of the plants survived and we had lots of vines.  After the first frost I dug them out.  There were lots of fingerling size tubers, but few of any size.  There was one large sweet potato, a few medium size and lots of small ones.

2012 Sweet Potato Harvest
2012 Sweet Potato Harvest

My conclusion was that it was too dry under the plastic.  The one large potato was at the edge of the bed where the ground sloped away receiving more water.  I did cure the sweet potatoes and we enjoyed them.

The next summer, 2013, I was ready to try again, but didn’t have much time.  I ordered the slips and planted them alongside a barn wall facing south thinking it would maximize the heat with the sun reflecting off the wall.  The vines grew well, but no tubers formed at all so it was a total failure.

I am fairly persistent when I get something in my head so I wanted to try again.  In the spring of 2014 as I was doing research I found a book called “Sweet Potatoes for the Home Garden With Special Techniques for Northern Growers”.  It is written by Ken Allan who lives in Kingston, Ontario.  I had to order it directly from him as it was not available in any bookstore I could find.

I learned some new techniques from the book and decided to plant 100 sweet potato slips.  This time I ordered from a sweet potato farm that would send me the slips when I wanted them.  The farm that I bought from was George’s Plant Farm.  The slips arrived when I wanted them and they looked great.

We made raised rows and covered them with clear plastic burying the edges in the soil.  We made sure the soil under the plastic had been thoroughly soaked to prevent lack of moisture under the plastic.  When the slips arrived we planted them by making X marks in the plastic and then adding dirt on top to seal the hole made for the slip.  Here is a picture after a couple weeks of growing.

Sweet potato raise rows
Sweet potato raise rows

We had two 25′ rows and two 15′ rows planted in sandy soil that was amended with compost.  We also planted some into rows in heavier clay / loam soil for an experiment.  All the slips grew well.  I did minimal weeding.  I was a bit worried because the summer seemed to be on the cool side.  It was also very wet and it seemed like the rows in the clay were sitting in excess water.  The two 15′ rows were the only rows that were watered, the rest were on their own for moisture due to their location.

By Sept 13th we had a killing frost and here is what the same raised row looked like.

2014 Sweet potatoes after frost
2014 Sweet potatoes after frost

Here is what it looked like when we started pulling back the plastic.  We didn’t do a very good job of covering the edges of the plastic with dirt which allowed some weeds to grow under the plastic.  If the plastic was sealed well, then very little vegetation should grow under the plastic.

2014 Harvest Sweet Potatoes
2014 Harvest Sweet Potatoes

Here is a close up of the tubers under one plant.

Sweet Potato Harvest Close Up
Sweet Potato Harvest Close Up

Here is the harvest from the two 25′ rows.  Unfortunately I didn’t get around to weighing the box and determining a per plant yield.

Part of the 2014 Yield
Part of the 2014 Yield

In summary the yields didn’t seem to vary between the sandy soil beds and heavy soil beds.  The beds that were watered did not do better than the others.  All beds had some potatoes that were split from growing too fast.  Ideally the potatoes would be nice and smooth.  We also had some potatoes that were damaged by rodents chewing the tops of the potatoes.

Sweet potato with growing splits
Sweet potato with growing splits

After harvesting it is important to cure the sweet potatoes.  The curing process ensures that the potatoes will keep for a long period of time.  We are still eating sweet potatoes that were grown last year.  They are in excellent condition.  I will post about curing sweet potatoes some other time.

Now, we are upon the 2015 growing season.  I want to plant 200 sweet potato slips this year.  I’ll keep you posted on how it goes!