Yes, greenhouses keep plants alive in winter by trapping solar heat and blocking wind, frost, and precipitation — but how well depends directly on panel thickness, ventilation control, and whether supplemental heating is added.
A greenhouse works by letting sunlight in and slowing heat loss through the walls and roof. Thicker polycarbonate panels hold that heat longer after sundown, which is where the spec actually matters in practice. A 6mm multi-layer polycarbonate greenhouse maintains meaningfully warmer overnight temperatures than a 4mm structure in the same conditions — the extra wall layer reduces thermal transfer. In climates with sustained hard freezes, most greenhouse growers pair panel thickness with a small electric or propane heater to hold a minimum overnight temperature, typically 40–50°F for cold-hardy crops.
- Yardenaler greenhouses use 6mm multi-layer polycarbonate panels — the same thickness standard used in commercial greenhouse construction.
- 6mm polycarbonate retains more overnight heat than 4mm panels, which matters most when exterior temps drop below 25°F.
- Adjustable roof vents that open to 45 degrees prevent overheating on sunny winter days, which can stress plants as much as cold does.
- Most cold-hardy crops (lettuce, kale, spinach) survive winter in an unheated greenhouse down to approximately 28°F exterior temperature.
- Yardenaler greenhouse sizes range from 48 sq ft (6×8 ft) to 128 sq ft (8×16 ft), affecting how quickly interior air cools on cold nights.