Greenhouse Poly Cover Extend your growing season and protect tender seedlings. Crafted from thick, durable greenhouse poly Dual-direction zippers for controlled airflow Double-sided roll-up doors Magnetic base for a clean, secure seal Simple. Strong. Smart. Whether you’re blocking pests, buffering the weather, or giving your plants a cozy head start, this cover system grows right along with you. Compatible with Sproutbox Garden Raised Beds —just snap it together, zip it up, and garden on.