Fiberglass planters are made with plastic that is reinforced with glass. As such, these planters are lightweight and durable. If you want to design your garden in a certain way, these planters are also a good idea because they can mimic any material. Fiberglass planters are also: • Weather-resistant, so it's safe from extreme heat, freezing, and other elements • Non-porous, so moisture is not lost. • Color will not fade over time. But there are some disadvantages to fiberglass panters as well. For one, the non-porous material means that you should always have a drainage hole. Some fiberglass planters can also be expensive.