Plastic greenhouses have a number of advantages over glass greenhouses. For one, they're much cheaper to construct and maintain. They're also usually lighter in weight, making them easier to move around if necessary. Additionally, plastic is generally a better insulator than glass, meaning that it can help keep your plants warmer in cooler weather. However, there are also some drawbacks to using plastic greenhouses. One is that they don't tend to last as long as glass greenhouses; over time, the sun's UV rays can break down the plastic, causing it to become brittle and eventually crumble. Additionally, plastic doesn't transmit light as well as glass does, so your plants may not get quite as much sunlight as they would in a glass greenhouse. Overall, plastic greenhouses have some definite advantages and disadvantages. If you're on a budget, or if you need a greenhouse that's easy to move around, a plastic greenhouse may be a good option for you. However, if you want your greenhouse to last longer and/or provide your plants with the best possible growing conditions, you may want to stick with a glass greenhouse.