Where you put your greenhouse matters more than what you put in it. Placement determines how much light your plants get, how hard your heater works, how well your ventilation performs, and how convenient the greenhouse is to use daily. A well-sited greenhouse produces more with less effort. A poorly sited one fights you every season.
The long axis of your greenhouse should be oriented to capture the most useful light during the season when light is scarcest:
East-West orientation (long axis running east to west): Maximizes south-facing wall exposure during winter, when the sun is low on the southern horizon. This is the recommended orientation for year-round growing in northern latitudes (above ~35°N). Your largest glazing surface faces south, capturing maximum winter sunlight.
North-South orientation (long axis running north to south): Distributes light more evenly throughout the day as the sun tracks east to west. Better for summer-only or warm-climate greenhouses where winter light isn’t the limiting factor, and where reducing one-sided overheating is a priority.
For most U.S. growers who plan to grow through winter, east-west is the better default. If your lot layout only allows north-south, you’ll still grow perfectly fine—just expect slightly less winter light on the north side.
Your greenhouse needs a minimum of 6 hours of direct sunlight daily during the shortest days of the year (December–January). Eight or more hours is ideal. Survey your site carefully:
Wind is the enemy of greenhouse heat retention. A windbreak on the prevailing-wind side reduces convective heat loss by 20–40%. Effective windbreaks include hedges, solid fences, building walls, and windbreak fabric. The windbreak should be located roughly 2–4 times its height away from the greenhouse (e.g., a 6-foot fence works best 12–24 feet from the greenhouse).
Avoid low spots that collect water. The site should have a gentle slope (1–2%) away from the greenhouse on all sides. If your property is flat, consider raising the greenhouse site slightly with a compacted gravel pad. Good drainage prevents standing water around the foundation, ice formation against the base in winter, and soil saturation issues.
You’ll need water and electricity—eventually, if not immediately. Site your greenhouse within reasonable distance of:
Running water lines and electrical conduit after the greenhouse is built is expensive and disruptive. Planning for utility access during site selection saves headaches later.
An uneven base creates frame stress, panel gaps, and drainage problems. Level the site before assembly. Options from simplest to most permanent: compacted gravel pad, treated-lumber perimeter on gravel, concrete pier blocks at frame corners, or a full poured slab.