How to Build a Small Greenhouse

A mini greenhouse is a small, enclosed structure that creates a microclimate for growing plants. While greenhouses can be any size, a mini greenhouse usually covers less than 10 square feet of ground. With the right materials, a DIY mini greenhouse can be affordable, attractive, sturdy, and functional. 


What to Know When Building a Mini Greenhouse


When learning how to build a small greenhouse, there are a few things to know. 


  • It is important to have adequate ventilation so that your plants can breathe. 
  • Heat and humidity can easily rise in greenhouses. Use a digital thermometer to measure the temperature and humidity to ensure the levels are appropriate for the plants growing inside. 
  • Mini greenhouses are great environments for starting seeds or cloning plants. 
  • You can grow almost anything inside a miniature greenhouse. Let your imagination and green thumb run wild!
  • Mini greenhouses can be designed to hold one or multiple shelves. If your mini greenhouse has multiple shelves, keep in mind that the lower shelves will receive less sunlight than the top shelf. Strategically place your small greenhouse in a location where all the shelves will receive the right amount of light for the plants growing inside. 
  • A mini greenhouse designed to protect plants in cool temperatures is called a cold frame. A cold frame is designed to passively collect solar energy to fuel the plant growth. 
  • Cedar is the best wood for outdoor garden projects because it is naturally resistant to rot and rodents; however, any new or recycled wood will work. 


Tools & Materials for Building a Small Greenhouse



  1. A table saw or hand circular saw with a plywood blade
  2. Heavy duty scissors
  3. A drill 
  4. Measuring tape
  5. Pencil
  6. Protective goggles and gloves



  1. Cedar 1x2s or any kind of wood planks
  2. Cedar or plywood sheets 
  3. Sand paper
  4. Wood screws
  5. Hinges
  6. Barrel bolt latch or handle
  7. Clear TUFTEX Corrugated Polycarbonate panels 
  8. 100% silicone or butyl tape for sealant, optional
  9. TUFTEX Fasteners


6 Steps in Building a Mini Greenhouse


  1. The first step is to determine the size and shape of your mini greenhouse. Is it short or tall? What are the dimensions? Is there a single shelf or are there multiple shelves? Create a drawing that describes the design of your mini greenhouse.
  2. The second step is to measure and cut the components of the small greenhouse. Always measure twice before cutting, and use the appropriate protective gear when handling machinery. After cutting the wood, sand the edges for a nicer finish. 
  3. The third step is to assemble the wood frame. Drill pilot holes to prevent the wood from splitting from the screws. 
  4. The fourth step is to attach the clear TUFTEX Corrugated Polycarbonate panels. Drill pilot holes in the panels and use TUFTEX Fasteners to secure the panels to the wood frame. 
  5. If you need to create a waterproof seal on the top or sides of your mini greenhouse, the fifth step is to apply the silicone or butyl tape along the edges of the polycarbonate panels. However, you may want to leave the gaps between the wood frame and raised corrugations to allow for airflow to the plants. 
  6. The fifth step is to attach the door or doors to the frame with the hinges. If you would like, you can add a barrel bolt latch or decorative handle. 

Once your mini greenhouse is complete, it’s time to celebrate! Fill your small DIY greenhouse with plants and appreciate your hard work. For more greenhouse and garden cover inspiration, check out Onduline’s greenhouse project page. For all of your DIY roofing and siding materials, visit Onduline’s product page.