A greenhouse structure may be covered with glass or plastic sheets. Because it is two to three times as robust as conventional glass, yet it may still shatter, tempered glass is often utilized. As a result, glass needs a far more solid framework than plastic does. Double-layer plastic sheets may be purchased that are very durable and resistant to wear and tear. Even while plastic is a useful resource, recycling it frequently results in micro-plastic waste, which pollutes the environment. There are also fiberglass sheets available. Which panel clarity is best for your needs will be determined only by your goals for the garden. A clear panel is ideal if you want to germinate seeds and develop seedlings that will later be transplanted into the garden. To help germinate seeds, the transparent panels let in direct sunlight. If you wish to develop plants to full maturity, you should use opaque panels. The uniform distribution of light provided by an opaque panel ensures a healthy and even development of the plant. There are two types of greenhouses: those that have transparent panels and those that don't have any panels at all. ​