Greenhouse Notes

The greenhouse is all put together and working well. It looks like a giant Wardian case sitting out in the garden and it's filled with lettuces, leeks, carrots, and onions. I have also planted three varieties of tomato and all are doing well. There is Early Girl, Sweet 100, and another variety of cherry tomato whose name escapes me. I expect to begin harvesting tomatoes from the greenhouse around June 15, or perhaps earlier. I also have my tomato starts for the main garden in the greenhouse right now.

However, as well as it is working, it has some problems. It can get way too hot inside and also, it's drafty which cools it off way to quickly at night. I need to address both problems, but the draftiness is the more important of the two.

The glazing is the problem. The glass needs to be more tightly sealed to the frame. I need to remove each section of glass and add a strip of Mortite to the top and bottom edges of the glass and to the center joint where the pairs of panes over lap.

The small aluminum tabs that join the panes are also insufficient because they create an unnecessarily large gap between the panes. This allows a lot of cold air infiltration. I am going to replace the center tab with a long strip of heavy aluminum foil cut from a disposable oven drip pan. This, along with additional strips of Mortite should seal the gap.

I also need to work toward double glazing the entire greenhouse. I think the best way to do this is to replace the glass with twinwall polycarbonate panels. These panels can be cut to the two by four size of the openings and will eliminate most of the drafts. However, it was expensive to buy the glass and it seems a waste to remove it. Also, the plastic is not as pretty as the glass.

I'll replace the glass in stages, starting with the North wall and then the north roof. The north wall will mostly be hidden by plants and little light comes through it anyway. I'll use the glass panes to glaze Dutch lights for my cold frames, and possibly to construct storm panels to put on the South walls and roof.

Tightening up the end walls is more problematic. The west wall can be reglazed with plastic panels, although this will require some fancy cutting. The east wall, with it's door is more difficult. I certainly see why an attached greenhouse is recommended because it is very difficult to get in and out of the greenhouse without letting all the warm air out in the winter. I need to create some sort of airlock.

Possibly the thing to do would be to put in some sort of plastic curtain inside the door way. This could hang from the frame at the first bay, secured to furring strips perhaps. I could fasten the furring strips to the aluminum channels with the T-bolts that I can buy from Charlies Greenhouses.

I also need to set up solar heat storage. My current plan is to build a shelf that will line the north wall up to the roof line and hold gallon bottles of water. I'll size the shelves to fit one gallon orange juice bottles. If possible, I will paint the bottles black to help them absorb more heat. Possibly it would be helpful to put a layer of celotex or similar foam insulation on the north wall between the glass and the water bottles.

I need to think about a misting system to cool things off too.