A garden cloche is a portable, low-to-the-ground covering that functions as a miniature greenhouse for individual plants or short rows. The primary purpose of a cloche is to extend the growing season, allowing gardeners to start planting earlier in the spring or continue harvesting later into the fall. Modern versions utilize glass, rigid plastic, or flexible plastic sheeting over hoops. They all share the fundamental ability to trap solar heat and create a warmer microclimate.
Preparing the Site and Installing the Cloche
Preparing the growing area before installation ensures the cloche provides maximum benefit to the plant. The soil should be thoroughly moistened before covering, as the cloche will block natural rainfall and help retain the existing moisture. For warming the ground for early planting, you can place the cloche over the bare soil seven to fourteen days before sowing seeds or transplanting. This pre-warming period can increase the soil temperature by several degrees, speeding up the germination process.
Once the plants are in place, securing the cloche is necessary to prevent damage from wind. Lightweight plastic cloches require anchoring, often with wire pegs, stakes, or by mounding soil around the edges. Tunnel cloches, which cover a row, should have their plastic or fleece covers pulled taut and secured along the long edges with boards, bricks, or sandbags to minimize wind resistance. For individual bell cloches or recycled containers, simply burying the rim slightly or placing a heavy stone on top will stabilize them against sudden gusts.
Using Cloches for Specific Gardening Needs
The most common application is to achieve a head start on the planting season by forcing early growth. Cloches capture solar radiation, warming the air and soil beneath them, which allows heat-loving crops to germinate and establish weeks earlier than they could in open ground. The elevated soil temperature promotes faster root development, resulting in more robust plants once the covers are removed.
Cloches are also utilized for providing a buffer against adverse weather, particularly late spring or early autumn frost events. The trapped heat and moisture create an insulating layer that protects tender seedlings from cold snaps and chilling winds. Heavier grade cloches can offer a few degrees of frost protection, which can make the difference between a plant surviving a cold night or succumbing to it.
A third distinct application is using the cloche as a physical barrier defense for vulnerable plants. The rigid or mesh material prevents common garden pests, such as rabbits, birds, and various insects, from accessing the foliage. This physical exclusion is particularly useful for young seedlings that are most susceptible to damage, offering protection until they are large and strong enough to withstand minor pest pressure.
Essential Daily Management and Ventilation
The primary danger of using a cloche is allowing the internal temperature to climb too high, which can quickly scorch or “cook” the plants. Ventilation is therefore an active part of daily cloche management, especially on sunny days. When the ambient outside temperature reaches approximately 50°F (10°C), the cloche needs to be opened or propped up to release excess heat and allow for air exchange.
This daily air circulation prevents temperature extremes and mitigates the buildup of excessive humidity, which can lead to fungal diseases like damping off or powdery mildew. For individual cloches, this means lifting them completely or propping them up for several hours during the warmest part of the day. Tunnel cloches usually require opening the ends or lifting the sides of the sheeting to create a cross-breeze.
Gardeners must also monitor soil moisture, as the cloche prevents rain from reaching the plants and warmer temperatures increase water consumption. If the soil dries out, the cloche must be temporarily removed for targeted watering. The cloche should be removed permanently when the plants have hardened off and the threat of frost has reliably passed, typically when nighttime temperatures remain above 50°F.