Greenhouses concentrate both heat and sunshine to maximise plant growth and harvest. The clear windows both let in sunshine and insulate the greenhouse. Windows come in both glass and polycarbonate (clear, hard thermoplastic). Both can be cleaned with water and mild disinfectants.
Cleaning greenhouse glass is important. Over time the panels start getting dirty outside, and algae can build up on the inside. The more dirty the windows become, the less light enters the greenhouse, and the less heat and light the plants receive. Cleaning the glass and maintaining the greenhouse also reduce plant disease and pest infestation.
Sponge warm to hot water onto the greenhouse glass and let it sit for a few minutes. Use a ladder to reach high panels.
Scrub the glass thoroughly with a mix of warm water and mild detergent using a sponge, or a tough nylon brush for more stubborn dirt build-up.
Let the glass air-dry.
Polish one pane at a time with glass cleaner. Dry the glass with a clean towel.
Turn off any electricity in the greenhouse. Unplug any appliances and cover the electrical sockets with waterproof tape.
Mix warm water and greenhouse disinfectant to the ratio dictated by the instructions on the product. Greenhouse disinfectant is a fungicide that will kill algae and help keep it from regrowing.
Dip a tough nylon brush into the solution and scrub the glass or polycarbonate.
Rinse the displaced dirt and algae off the glass.
Dry the glass with a clean towel.
Only wash the inside of the greenhouse during the winter or right before spring to minimise damage to plants. If you must clean the inside during the growth period, remove the plants into another warm place. Buy greenhouse cleaners with natural ingredients only. It is best to ask an expert at a garden shop.