Utah State University Extension

Did you know greenhouses conserve water? But they’re not the only option!

A greenhouse can reduce water use by up to 50-90% compared to traditional outdoor growing by reducing evaporation and improving irrigation efficiency. But for many home gardeners, high tunnels and low tunnels may be a more practical (and affordable) way to save water while extending the growing season. Here’s the difference:

Greenhouse
• Permanent structure
• Uses active heating & cooling
• Higher cost
• Great for intensive growing

High tunnel
• Walk-in structure with no climate control
• Grown directly in the soil
• Moderate cost
• Can reduce irrigation needs by roughly 30-50%

Low tunnel
• Simple temporary cover over crops
• No climate control
• Low cost and beginner-friendly
• Can reduce irrigation needs by about 24-40%

These systems help conserve water by reducing evaporation from the soil and blocking drying winds. https://extension.usu.edu/agriculture-and-natural-resources/irrigation-high-tunnels

**One important note: tunnels and greenhouses are primarily tools for season extension not for growing through peak summer heat without management. Temperatures inside these structures can exceed 140°F during the day and damage plants if they aren’t ventilated properly.

To help manage summer heat, growers often replace plastic coverings with 30% shade cloth (reducing temperatures by 5-10°F). These practices can also help crops like tomatoes and peppers ripen earlier while reducing issues like sunscald and blossom end rot.

Pairing tunnels with drip irrigation and mulch can improve water savings even more.