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Living in an area where the growing season is so short (less then 3 months), I start most of my plants indoors and then place the seedlings in my temporary greenhouse to continue growing until planting season is here. My greenhouse is more like a large cold frame as I do not heat it. I am using this temporary greenhouse to gain some insights into someday having a permanent structure. Click here for links that contain information about greenhouses.
The shell is a thick, reinforced, fairly clear greenhouse plastic. The front door is merely a zipper; the zipper originally opened only from the bottom but I put a second slider on the zipper tape so I can open the zipper from the top also. There is a small (10x15 inch) screened window in the back wall that has a plastic cover held in place with velcro. The framing is 2 inch PVC pipe cut to length and held together with PVC fittings. The roof frame is 1 inch PVC pipe formed into a curved shape. The footprint is 6.5 x 9 feet.
A greenhouse, of course, needs a source of light (the sun) and some heating mechanism. Through my usual "learning experiences", I found that for this area I also need to consider:
- Wet, Heavy Spring Snows. We can have snow showers through
the first week in June. These late spring snows are often 8 to 20 inches and any greenhouse structure needs to be able to support and/or shed this heavy snow.
- Wind. My temporary greenhouse is just that - temporary. It is not permanently fixed to the ground and the inner support structure is held together by friction. A strong wind can (and has...) blow the whole structure down or skittering across the driveway. I firmly attach the shell and bottom structure members to the ground with garden staples (u-shaped bent pieces of heavy wire) and use nylon rope to hold the inner rectangle together.
- Brilliant Sunshine. This temporary greenhouse is not vented enough for the clear, bright sunshine we often (happily) have in the spring. The temperature inside the greenhouse can exceed 120ºF on some days. Plants really hate to be that hot!. I usually open and tie back the front doors to let fresh air circulate into the interior. This leads to my next "learning experience".
- Critters. No, not insects but cute, fuzzy critters. Chipmunks have no fear of venturing into structures and tend to view my young seedlings as a wonderful opportunity for a tasty meal. Until I took precautions, the chipmunks would enter the front door and eat most of my seedlings. They especially love broccoli, cabbage, and cauliflower.
- Hail. We have had hail stones about 1 inch across. Although the greenhouse material is very thick, strong reinforced plastic, hail has put numerous holes in the roof. I use clear glue and heavy plastic from freezer bags to patch the holes. I also take down the greenhouse by mid-June before, hopefully, the hail storm season starts.
This photograph and the one above were taken in April during a spring snow storm. As you can see, the greenhouse now sheds snow quite well. It did not always do so well. The second year I used the greenhouse, I had all my plants in the greenhouse when, during a typical wet spring snow, the inner supports did not hold the roof up and, as the temperature plunged below freezing, the roof collapsed down on my plants. Every one froze.
Jack, being both a dear friend and a mechanical engineer, redesigned the inner supporting PVC structure and added the necessary elements to support heavy snow and, more importantly, to allow the snow to slide off the roof.
Here is my temporary greenhouse in better weather. I have the door unzipped and held back. The aluminum foil, held in place with rocks, keeps the chipmunks out. I put in some temporary shelves so I can view and water the plant trays easier. I also put a ring of rocks along the bottom edge of the shell to hold the plastic in place and to keep the wind from blowing under the walls.
I use bottles filled with water to heat the greenhouse overnight. Filling the bottles on a cold, spring day when I'm setting up the greenhouse is not fun but the water filled bottles work really well to heat the greenhouse. I have had seedling survive when the outside temperatures drop to about 15ºF just using these bottles. As the weather warms during May and I do not need as much overnight heat, I start using the water in the bottles to water the seedlings. This way, I do not feel I've wasted water in this semi-arid area.
One of my favorite things to do in the spring is to go out to this greenhouse in the morning and tend the seedlings. The outside air is still cold but the greenhouse is an environment of its own and the warmth and the brightness are welcome after our long winter. I sit on a small stool set between the shelves and dream of the warm summer days to come and my gardens to be. Almost heaven. |
This photograph and the one above were taken in April during a spring snow storm. As you can see, the greenhouse now sheds snow quite well. It did not always do so well. The second year I used the greenhouse, I had all my plants in the greenhouse when, during a typical wet spring snow, the inner supports did not hold the roof up and, as the temperature plunged below freezing, the roof collapsed down on my plants. Every one froze.
