Considerations for determining optimum location for growing, air flow, snow shedding and ground moisture
The first bit of advice we share when asked that question is “Do not put a greenhouse in a place that is not good for anything else”.
You need to pick the best spot to accomplish the goals for your greenhouse. Any of the reasons why this spot would be less than desirable, will come back to haunt you.
This is particularly true when it comes to ground water. If a particular piece of land is always moist or has a very high water table, moisture will be an ongoing problem. A greenhouse will trap and exaggerate excess moisture and become a very unhealthy spot for plants.
If the soil is sub-standard or undesirable where you put the greenhouse, you will be putting extra effort into bringing the soil up to standard.
Proper consideration needs to given to shading on the property. Plants grow in direct proportion to the amount of daily light they receive. Really analyze where and when shade happens. Vegetables and flowers need sun.
A greenhouse needs to be level from side to side so shed snow uniformly. With uneven snow load on a building, it will surprise you how little snow can be a problem.
Excavation to level a site is usually expensive and messes with the make up of the soil. There are ways to build up the low side if that becomes necessary for the location of your choice. Some end to end slope is not a problem structurally.
It is generally acknowledged that a north/south orientation will pick up the sunlight better but this is not a serious consideration unless you are into production crops.
If your prevailing winds are constantly hitting the side of the structure, there will be a sideways push which is good to avoid. This orientation will also encourage uneven snow loading. Ventilation is typically easier if the prevailing wind hits the end of the building.
Since the chances of having the “perfect” location, is not likely, it is important to evaluate all of the angles. Some of the undesirable points can be worked around better than others.
By doing a thorough assessment and then prioritizing, you will be able to come up with the closest to perfect that is practical. You will also have an idea beforehand on what needs to be done sooner than later.
Here is to happy planning and planting.