Greenhouse

Structure

A greenhouse is an enclosed structure with transparent walls or roof panels that capture light and heat. It gives gardeners the greatest environmental control among common season-extension methods. Greenhouses are often used for seed starting, transplant production, and growing crops beyond the normal outdoor season.

How it works

Sunlight enters through the transparent covering and warms surfaces, soil, containers, and air inside. The enclosed shell reduces heat loss and blocks wind and precipitation. Depending on design and management, a greenhouse can maintain more stable temperatures than simpler structures. Ventilation, shading, and moisture control are all important because the same enclosure that holds warmth can also trap excess heat and humidity.

Best for

Greenhouses are best for raising seedlings, protecting tender plants, and growing crops when outdoor conditions are too cold or wet. They are useful for gardeners who need a controlled space for propagation or a longer production window. They can support both cool-season and warm-season crops when managed carefully.

How to use it

Place the greenhouse where it receives strong sun, especially in winter and early spring. Organize benches, beds, or containers so air can move well around plants. Vent on warm days and monitor moisture closely to avoid overly damp conditions. Harden plants gradually before moving them outdoors so they adjust to wind, sunlight, and cooler temperatures.

Tips

A simple thermometer at plant level helps guide venting decisions. Clean coverings regularly so light transmission stays high. Avoid crowding plants, since dense canopies reduce airflow and increase moisture problems.

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General guidance for US gardens. Pair with your local frost dates and hardiness zone. Page updated Aug 4, 2026.