A tropical greenhouse is a greenhouse designed to grow tropical plants in a controlled environment. In order to grow tropical plants, the inside temperature of the greenhouse must be kept far above the freezing point at all times to prevent damaging the plants. If you are not in a hot climate, you will need to limit the amount of heat loss by using high end glazing and active heating.
Choose the tropical plants which you would like to grow. Make sure to choose plants that can survive with the amount of sun that your location has.
Build your greenhouse frame using standard framing techniques. Build a subfloor using lumber or a concrete slab. Make sure to use board foam insulation to insulate the floor, especially if you are in a cold region.
Close the north wall and the north part of the roof if you are using a gable roof to prevent drafts and wind.
Use siding on the outside and use bat or foam board insulation in the voids to insulate the wall. Use wood siding to close the inside wall after putting in the insulation.
Paint the wall white to maximise the sun's reflection toward the inside of the greenhouse. This will help create additional heat.
Install double or triple wall glazing based on your climate. Check for air leaks and make sure that potential leaks are plugged to avoid plant damage.
Purchase or repurpose 55-gallon drums. Clean the drums out and fill them with water. The water absorbs energy and acts as a buffer in case of cold temperatures or if the heating system malfunctions.
Install a heating system. You can get electric, propane or wood heaters to help heat your greenhouse. Install fans in the ceiling of the greenhouse to avoid pockets of hot or cold air.
Install a digital thermostat and connect it to the heater if you want to maintain the same temperature automatically. Remember to set a lower temperature at night.
Set-up a greenhouse cover if you live in a cold climate to minimise heat loss at night.
Only use wood to close the north wall. The greenhouse will be humid and drywall can degrade rapidly, which can interfere with the stability and insulation of your greenhouse. You can use the water drum in an open or closed position. If you choose to leave the water drum open, the greenhouse will have a higher humidity level, but you will need to cover the drum sometimes to reduce the humidity level. Installing a wood heater has the added advantage of providing plants with additional carbon dioxide.