Farm Greenhouses Yesterday the temperature here was ten degrees below average. The weather has been like this for a couple of years now. We keep setting records for low temperatures and then for high temperatures. In some areas this has ruined farmers and today it is giving this gardener a headache. Julie is getting reports from Northern Saskatchewan saying a lot of the farmers will go under this year due to the weather. One solution to this problem is a greenhouse. Sure, we have a sun room and a small free standing greenhouse. I've got row covers, plant cones, and giant hot caps made out of plastic pipe. All these solar structures work and could be called greenhouses, but for someone who whats fruit trees and large beds a different greenhouse is needed. Actually, this has gone beyond thinking and i find myself out measuring and leveling an area whenever the rain stops. The ecological cost of building a big greenhouse is mostly in manufacturing the covering. The farmers in this area use a 6mil plastic which lasts about 4 years. If you cover the greenhouse with shade cloth the plastic lasts up to ten years or more. This seems like a reasonable use of technology when one considers all the food and enjoyment which results. If we ignore all the ecological questions and get down to building things get easier. The farmers in this area have standardized on one design that is very easy to construct. The shell is metal pipe arched over the area to enclose. This can be small or larger than a house. The ends are usually constructed from wood with a door. For ventilation the sides can be rolled up in the summer. The plastic in old versions of this greenhouse was held down with tack board but now many are switching to a clip system which i plan to try. A small metal channel is screwed to the sides and clips are used to hold the plastic in this channel. The whole thing costs about the same as the small hobbyist greenhouses sold in catalogs but is about ten times bigger. The basic shell greenhouse is a good season extender and rain shield in this area. It can be used to grow some plants which are marginal in this zone. If we wanted to grow actively all winter then some additional heating is needed. Solar is the natural choice and a second choice would be animals. Things like chickens and ducks. My preference is to with solar and use the one ingredient we have lots of "water". The problem with water is finding a suitable container to store large amounts of heat for long periods of time. I ran the math once and decided most of the water needs to be buried and connected to the earth. This increases its ability to cool and adds large amounts of heating capacity. Anyone tried this? I have some data on the pit greenhouses that were popular years ago and they seem to function about the same. jeff
