Greenhouse: Part 2

It has been a while since I last wrote about the greenhouse. Since then there have been the usual ups and downs but things have progressed and it has been performing well. There is still work to be done, but I thought I would document where we are now.

Greenhouse Beds

Growth started in the beds in mid-April. Next year, with all insulation/seals in place as well as active systems, we are hoping to get even more of a jump on our growing season as well as producing some crops year-round.

Heat Battery

Despite the unwelcome complications, two IBCs (Intermediate Bulk Containers) did get buried in the center of the greenhouse. They are filled with 500 gallons of water which might act to slightly smooth out temperature fluctuations. The real advantage, though, is the ability to add active systems. I have run a 4″ PVC pipe out of the greenhouse. At some point before next fall I will run lines of PEX out through this tube and hook them up to some evacuated tube solar panels we have from a previously abandoned project. Attached to a pump and controller which we have from that same project, this should be able to actively collect solar heat in the winter and heat up the 500 gallons of water.

I also ran a brief test on an heat distribution system based on a car radiator. A small pump circulates water through the radiator and a fan blows air past in order to either help put excess heat from the greenhouse into the water or take heat out of the water. Although the mechanics worked, I found that the amount of heat it could capture from within the greenhouse was minimal. I am more optimistic that it can be used to blow hot air in the winter when the IBCs have been heated using the active solar system. I am also hoping that performance will increase when I use the fan that I procured along with the radiator rather than just a small squirrel fan blowing vaguely in the general direction of the radiator.

The other option for active heat distribution in winter would be to run PEX runs through the beds themselves and then circulate the heated water through. This would directly heat the soil in the beds and may prove to be a good option in certain instances.

Cold/Warm? Frame

Cold/Warm Frame

Built above buried IBCs (visible through missing decking on the left), this second layer of glass provides a good area for starting seedlings while nighttime temperatures in the main greenhouse are still inadequate.

Although part of this water system is covered with decking, I also built a second glass-covered area on top of a good portion of one of the IBCs. This provides a second layer of glass for plants growing inside and has already proven a viable area for starting seedlings in advance of the main greenhouse being frost-free. At the end of this last winter we put foam on the floor of the box and included a small heating mat to provide auxiliary heat when needed. Next winter we plan for the active solar collection to be functional, meaning that the slatted floor above the IBCs should allow warm air to pass into the area and help to maintain warmer temperatures.


Although there is still room for one more bed in the greenhouse, the first beds are in and already full of plants. I have also run cable lines above the central beds to allow Tamara to drop down weighted lines up which climbing plants can grow. The greenhouse is also already proving a valuable space for potted plants and seedlings/starters. This has been a mild year and we may already be past last frost but we are still a few weeks away from the dates where gardeners in the area traditionally consider themselves to be safe from late cold snaps.

Greenhouse, late April

The beds in late April. Well into the season of “infinite salad” and with some good progress on more varied crops.

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