Choose a level site with good sunlight and drainage
Check local building codes and permit requirements
Decide the greenhouse size and style
Select a frame material such as wood, aluminum, or steel
Select glazing material such as glass, polycarbonate, or polyethylene
Mark the layout and measure the foundation area
Build a foundation or base frame
Install the floor surface or ground cover
Assemble and secure the frame
Install roof supports and wall supports
Attach the glazing panels or covering
Seal joints and edges to reduce air leaks
Install doors, vents, and windows
Add shade cloth, fans, or automatic vent openers if needed
Set up irrigation and drainage systems
Install shelving, benches, and plant supports
Add heating or cooling equipment if needed
Test for stability, leaks, and ventilation
Prepare the interior for planting
Maintain the greenhouse regularly