MoonShadow's Greenhouse

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I've wanted a greenhouse for quite some time, and it wasn't until I had a "side line" website selling yard structures (gazebos, patio covers, carports and greenhouses) that I decided to buy one myself. I bought one made by the Sunshine Gardenhouse company out of Washington State, USA. It is one of their Mt. Rainier Series measuring 8' x 16' and made from Redwood with Polycarbonate Panels. At it's peak, it is 10' tall, has two Dutch Doors and two Roof Vents. As a retailer (drop shipper) for them, I was able to get it for wholesale.) You can read more about the structure here at http://www.gardenhouse.com/greenhouse-kits/mt-rainier-group/.

While it is well-made and I have enjoyed this greenhouse for the past 2 years, if I knew then what I know now, I probably would have gone a different route. I really wanted the greenhouse to extend our growing season in the Fall right up to the very cold weather and start off as early as I could in late Winter again...in other words, at least a 10 month greenhouse. Unfortunately, I really knew very little about greenhouse insulation and heating and taking advantage of solar energy and thermal mass. As a result, I have started making many modifications as you will see in this showcase, and will continue to make modifications as time goes on.

I'll start off with the original preparation and building, then move to what I have done/am doing to use this greenhouse over more months.

Here is a picture taken this past Summer, just so you can see the finished structure. You can see how the redwood is slowly turning a silvery-gray as it weathers. We decided to let it do that rather then sealing it, which would have to be repeated every few years.
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But let's start at the beginning.....
We started by digging out the foundation. You can see in this picture the 6 x 6's that were to be the foundation.
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And, laying down a bed of screenings (finely crushed rock and rock dust)

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And because we started so late in the season, and one thing led to another, that all we got done in the Summer of 2015. So, our chickens decided to make this dirt pile one of the favorite hangouts. Here is a picture of what the area looked like come Spring of 2016....a bit of a mess!
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So, we started moving the dirt away, laying and leveling the foundation.
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We loosely placed the structure's composite base, double-checked that everything was level...or, as level as we could get it.
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Filled in with some more screenings to "lock in" the foundation and create the interior floor...
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And, started to build.
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Automatic Roof Vent
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Shot from the interior looking out
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Laying the flagstone floor...
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And, sprucing up the exterior...I also added gutters and downspouts.
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Complete! And over the past two seasons, I have used the greenhouse to start all of my flowers and vegetables from seed, but for the life of me, I don't have any pictures of all the pots and flats I stated...not sure why...except one...
Some peppers...
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Now, in the dog days of Summer, not much goes on in the greenhouse as the temperatures can easily exceed over 100F (38C)and have risen as high as 130F (54C). After the first season, I wanted to plant some Fall crops, especially lettuce, spinach and onions, but soon found out as the weather turned cooler and then cold, the greenhouse had no real insulation factors. While day time temperatures were OK, at night the temperatures in the greenhouse mirrored the outdoor temperatures....much too cold to sustain any growth. It kind of took me by surprise. So, I decided I need to start making modifications for the late Fall, early Spring. Since I had made no provisions for insulating the ground around the greenhouse, and it would be very difficult to do that now that the greenhouse was built, I started researching other ways to grow and sustain during the cooler, colder months. December and January are probably out of the question as I would need to provide heat, and the cost for that is prohibitive.

So I stated making changes. The first thing I did was take out the existing benches. I bought 2 Cedar raised beds, and used the redwood from the old benches to create two 3 x 6 cold frames, effectively creating a greenhouse within a greenhouse.

Here is the beginning of this project...
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I then insulated the North Wall with Reflectix Insulation....2 sided foil with a bubble wrap in between.
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Put down concrete blocks to raise the cold frames off the ground.
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Set the raised bed frames on the blocks.
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Built the cold frame tops.
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Covered the frames with greenhouse film
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Fashioned a "floor" in the cold frames.
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Put down some weed block to keep any soil from working its way through any cracks.
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And, filled them with a mixture of 1/3 Perlite, 1/3 peat moss, and 1/3 compost (from one of my compost piles adjacent to the greenhouse)...and a couple of bags of cow manure compost for good measure!
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Nest, I set to work sealing up all the joints in the greenhouse. Depending on the gap, I used caulking, putty, foil tape or felt insulation. I sealed off the rear door, and put weather stripping around the front door. Any place a draft could come in, I sealed.

I also decided that if I could drop the ceiling height down a few feet, I could keep any warmth lower in the room. Did you know, the majority of greenhouse heat is lost through the ceiling? I installed two PVC pipes the length of the greenhouse just below the rafters. To this, I will attach more greenhouse film using clips". These clips will allow me to easily remove the film in warmer weather and attach shade cloth. The next step in the project as of this writing...
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While it is too late to plant anything in the greenhouse now (early December), I should be in much better shape in late Winter to grow a crop of lettuce, spinach and onions even before I start my seedlings for outdoors.

I have some other plans that I will work on over the next few months that should help to maintain temperatures....

1. Ground Perimeter Insulation While I should have insulated the ground around the greenhouse before I even began to build it, I didn't. So, I have decided to retrofit it with ground insulation. Our frost line is 42 inches. If I can retrofit ground insulation around the greenhouse, that will take advantage of the grounds thermal mass, helping to keep the greenhouse floor warmer in the winter and cooler in the Summer.

The easiest, but less effective way would be to dig a trench around the perimeter of the entire greenhouse foundation and vertically place 4" of pink board insulation. This will stop the migration of cold into the ground under the greenhouse. The problem with this is I don't think I can get more than a foot or so deep because of all the shale in the ground in this location of my yard, but even a foot would offer some relief.

The more effective way would be to dig down about 6 inches x 4 feet around the outside of the greenhouse and put in a Swedish Skirt....4 x 8 sheets of pink insulation, 4 inches thick and covered back up with soil. This would be the more effective method. You can see more information about ground insulation here: https://www.ceresgs.com/solar-greenhouse-basics-insulating-your-foundation/
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2. Solar Powered Water Heater The second plan is to create more thermal mass in the greenhouse, storing solar heat during the day to be released at night. Currently, I have 7- 5 gallon pails filled with water and the pails painted flat black. The water stores the sun's warmth during the day, and releases it during the night, but it is not enough volume. I could put in 55 gallon drums, but they would take up too much room.

So, I am most likely going to build a Solar Powered Water Heater. It will employ black hose in a solar collector, pumped by a solar pump into only 2 - 55 gallon drums. I have read where this can heat the drum water to well above 100F on a Sunny, but cold, day. Here is a picture from a plan I found. This plan is actually designed for what is called a thermosiphon loop, which means the warm water slowly moves itself to the barrel, but a pump would make it even more effective. You can read the whole article here: https://www.thereadystore.com/diy/9903/build-a-solar-powered-water-heater/
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So that brings me up to date as of the creation of this showcase. If I were to do this all over again, with what I know now, I most likely would build a very different greenhouse from the ground up, but a true thermal insulated, solar powered greenhouse is very expensive to build. One this size would probably run between $10,000 - $12,000. And, unless I have some rich uncle I don't know of, who dies and leaves me a fortune, that is not happening, so I'll continue to retrofit this one. It's fun, and a very enjoyable hobby for me. As I move forward, I will post more. I hope you find this showcase interesting. And, if you have any ideas or have other methods that you use in your greenhouse, don't hesitate to suggest them. I am still learning!

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