The purpose of a garden cloche is to act as a mini greenhouse that traps heat. It also shields young plants from cold, wind, and pests. You place this clear cover over one seedling or a small group of plants. The plants get warmth they would not get from open air.
I tested a glass bell cloche over one of my early tomato seedlings last March. I left its twin uncovered just two feet away. The covered plant put on visible new growth within seven days. The open one barely changed at all. That one test sold me on the garden cloche function for good.
The science behind this trick is simple. People have studied it for years. Clear glass or plastic lets solar rays pass through to warm the soil and leaves. Heat then gets trapped. The cover blocks it from escaping back into the sky.
Utah State data shows the inside of a cloche can heat up fast. The temp can run 20 to 40°F (11 to 22°C) above the outside air on sunny days. That swing saves a tomato from frost. The plant keeps right on growing strong.
Gardeners have valued this plant protection cover for almost 400 years. The first cloches showed up in Italy in 1623. They were hand-blown glass bells used to grow melons in cold spring weeks. Cloches were used at the Monticello farm too. They were used on tender crops to beat frost dates.
Today the cloche does three main jobs. Each one makes it worth the small bit of space in your shed. The first job is frost protection for tender plants. Use it when overnight lows drop below 32°F (0°C) in spring or fall.
The second job is pest exclusion. It blocks slugs, cutworms, cabbage moths, and rabbits that wreck young seedlings overnight. A solid cover stops them cold. You skip the spray, the traps, and the fence work on your part.
The third job is early planting. You can set out tomatoes, peppers, and squash two to four weeks before your last frost date. This head start gives you ripe fruit weeks ahead of neighbors who wait for safe weather.
Cloches give you a real season extension of one to four weeks on each end of your growing year. Pair one with rich soil and good seed stock. You turn a short cold-climate garden into a much more crop-rich plot.
The cloche pays back its cost the first season you use it well. Buy one bell cloche for your most prized seedling. Try it once in spring. You will see why this old tool has stayed in use for four centuries.
Most growers find one or two cloches handle the bulk of the work. Keep them clean between uses. Wipe off algae and dust each fall. A glass cloche can serve your garden for decades with simple care like this.
You can pair cloches with mulch and row covers for even more season extension. Mulch holds soil warmth at night. Row covers shield bigger crop rows that one bell can not reach. Used as a team they can add a full six weeks to your harvest window.
The cloche works best with crops you start from seed at home. Lettuce, spinach, and arugula love the warm soil cloches give them. So do early kale, peas, and beets. All these crops can be sown well before the last frost date with a cloche on top.
Remove the cloche on warm days above 60°F (15.5°C) to vent heat. Skip this step and your plants can cook in there. Set the cloche back on each evening once the sun starts to drop. This daily rhythm gives you the best of both worlds for free.
Read the full article: Garden Cloche Guide: 7 Best Uses
