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Sunday, September 23, 2012

Setting up the Solar greenhouse

One of the fall projects I have worked on is creating a completely solar greenhouse. I built this right over my moso bicolor so I can protect it as well as speed up its growth. I'm also using it to place some of my bamboos so they can grow a bit more through the winter. My objective is to insulate it well enough so that additional heating will not be necessary here in zone 6a. At this time of the year, the greenhouse typically raised the greenhouse about 5-20F, but those numbers typically increase in the middle of the winter.

Here's the outside of it.

This may not make sense, but I placed the door on the west side where the wind blows into it, but over the winter, there will be an entire tarp that goes over the greenhouse partially so that the wind and snow drift does not pile onto the door. It will also make it much easier to get inside when there's a lot of snow.

The solar vent was added yesterday to help with the air flow as carbon dioxide can be depleted with all the plants in the greenhouse. It works well because it only turns on when the sun is shining strong enough which also means that the plants will be photosynthesizing. That's when they actually need more air flow. I placed it on the south side of the greenhouse at a 45 degree angle to make sure it is functional.

Here are my 55 gallon drums for the heat sink. I am using black colored drums on purpose so that they can absorb more heat which can keep the greenhouse warmer through the night. I can also stick a fish tank heater in one of these which should be enough to keep the greenhouse above freezing however it will also make it even more humid than it already is.

Right behind the heat sink on the north side of the greenhouse, I already have reflective bubble wrap to help provide more insulation. It can also help reflect light back onto the plants. It's reflective capabilities should also help heat the greenhouse up a little bit more.

Here's the shelves that came with the greenhouse kit. I plan on using it to place either a small heater, a 400 watt metal halide, humidifier, paraffin lamp, or any heating device that will be enough to keep the greenhouse from freezing over.

Here are the 2 shoots on my bambusa ventricosa which have gained about 2ft of height after 3 days of being inside the greenhouse.

Finally here's the moso bicolor

30 Sept 2012: I decided to add a 4th 55 gallon barrel to the greenhouse, and it has been tarped on the north and west side so there is more insulation. It also allows the wind to blow over the greenhouse much easier instead of radiating too much cold air inside. I've noticed that north and west facing windows are more likely to have cold air radiate in so I'm providing extra insulation on that side.

Many more leaf filled bags will be stacked up on the north side to help provide even more insulation.


  1. Hi!
    Thank you for the link to your post! Your work is very interesting so if you agree I would like to put a link to your blog on my blog.
    I must admit that I really like the carbon dioxide part. It is an excellent idea! What is the lowest temperature during the winter you had?

    1. Sure. I don't mind my blog getting linked out as I'm simply sharing my gardening experiences with the world.

      The lowest temperature I have ever seen it drop in the greenhouse was 14.6F when it got below 0F outside, but I immediately added in the paraffin lamp which raised it back over 25F.

      This year, it hasn't gotten below 45F yet, and I have very good insulation there to deal with the zone 6 winters. I also added in a compost pile right in the middle of the greenhouse for a residual heating effect.

    2. It is done (link).
      Last year we had unusually low temperatures (-14°F) so I`m hoping that will not happen again. Heating ideas are great but impossible for me to do because most of the winter months I`m in other town. Mulching is the only option and covering them.
      I read yesterday in "Bamboos for garden" that people in China use compost for producing new shots for food during the winter. Compost heats up the soil and bamboo begins to create new shots.

    3. I really don't have to be around to keep the plants around in my greenhouse because at full insulation, the inside temperature will still hang around 20F warmer than the outdoor temperature, and it has always gotten well above freezing in the day time through the winter. Temperate plants don't mind minor freezes. A greenhouse can be insulated and made to the point where -14F doesn't even freeze the greenhouse.

      Compost does tend to keep bamboos going through the winter, but my compost pile is on the other end of the greenhouse away from the moso bicolor so it shouldn't heat up to the point where it causes shooting through the winter. Anyways we are still getting summer like temperatures in the greenhouse even in mid October.

  2. Thanks a lot Steve Lau for this wonderful idea on setting up a solar greenhouse... this is truly a big help for me to start my nursery..

    Online Plant Nursery

    1. If you are starting a bigger operation, it might be a good idea to find out how to overwinter each kind of plant. For example blue berries don't need any protection at all while some plants will overwinter well with large tarps. You should know their hardiness and how warm to keep them over the winter.

      There are also many more ways out there to heat and insulate a greenhouse. You could use a wood burner if you have access to a lot of trees. If you are making a huge greenhouse, a heat sink may be worth the effort as well.

  3. Thank you for sharing valuable information. Nice post. I enjoyed reading this post. The whole blog is very nice found some good stuff and good information here Thanks..Also visit my page  spray nozzles Ecologic Technologies Misting System Kits are loaded with great features!

  4. Hi,
    What kind of plastic cover is that with the green mesh?

  5. It is just a kit ordered off eBay for cheap.

  6. This is an interesting article. I have never seen a mass heater like this before. It is amazing what new technology they are coming out with these days. for Drum heater. Really your informative blog helpful for Drum heater

    1. It's good for semi-hardy temperate plants that can take some cold. It's still good to keep a small heater in there just in case there are nights that get super cold because there are instances when the drums can freeze over and be rendered inefficient, but if there's a backup for those emergency times, it's not that hard to over-winter plants.

  7. Hi Great Blog I Have Your Post It Very useful Information For Me And Others About Solar greenhouse But i Am Searching Drum heater Blog So Thank You For Posting And Sharing With us.