A greenhouse makes it possible to grow plants all year long, no matter the climate outdoors. Greenhouses are made of glass panes that trap sunlight indoors and creates a warm environment. In fact, the "greenhouse effect," or capture of UV rays, was discovered in greenhouses. Many gardeners use greenhouses to enjoy tropical plants all year-round or to start seedlings in the winter so they are ready to be planted in the spring. Proper maintenance of the greenhouse glass ensures that the greenhouse will work properly at all times.
Wash the glass using glass cleaner and newspaper or a soft cloth. Clean glass is needed for the greenhouse to work properly. Dirty glass will block sunlight from entering, and the greenhouse will not maintain the proper temperature and moisture.
Check around the edges of each pane to ensure that there are no gaps or cracks. Caulking is used to fill in gaps and holes.
Remove light scratches on the glass panes by rubbing an abrasive compound such as iron oxide, car polish or glass polish. Rub the polish on the scratch, using a circular motion. Only use light pressure when buffing, as you do not want to break the glass.
Tape up the cracked greenhouse glass with duct tape or UV-resistant clear tape until a replacement pane can be obtained. If the entire pane is broken, then tape a piece of cardboard in its place.
Obtain the replacement glass pane. If the pane of glass is a custom shape, then you may need a special order to cut the pane to size. Greenhouse glass panes can be found in standard square sizes. If you are unsure of what size pane to purchase, then take a sketch with you to the store.
Remove the broken pane of glass. For aluminium-framed greenhouses, simply remove the clips that hold the glass in place. For wooden greenhouses, the glazing pins, also called brads, must be removed to access the glass. Use a pair of pincers or small pliers to grab and remove the pins. For aluminium- and wooden-framed greenhouses, if the broken pane of glass has the above pane overlapping, then this higher pane must be removed first.
Clean the seal strip found around the aluminium frame before replacing the pane. Ensure that the seal is undamaged. If necessary, replace this seal. For wooden frames, remove all of the old putty found around the edges of the pane. This may lift out with the broken pane but can also remain stuck to the wood. A chisel works well for removing the putty, though be careful that you do not cut into the wooden frame.
Install the new glass pane. For aluminium frames, simply replace the clips. There should be a clip every 12 inches. For wooden-frame greenhouses, apply a new layer of putty around the sides and bottom of the frame. the top edge is left free of putty. Embed the glass pane into the putty. Once the pane is in place, then insert the glazing pins, using a small pin hammer.