It's hard for us to resist jumping the gun when it comes to putting out warm weather vegetable plants like Tomatoes, Cucumbers, Eggplants, and Peppers -- but the Plant Season Extender lets us do just that. These ingenious inventions allow planting two months earlier than normal, without any fear of freezing. Simply fill the individual plastic cells with water to create a free-standing cylinder that fully encircles your plant. Plant Season Extender releases warmth, insulates, and provides proper ventilation, while protecting plants down to 16°F. For added protection, the sides have extensions that can be used to conveniently close the center opening on cold nights. Measures 18in high and 17in across. Sold as a set of three.