What is a cloche used for?

All About Cloches

Gardeners are always trying to extend boundaries by squeezing in just one more tomato plant, or planting a shrub that should grow in a warmer climate zone. And we’d all like to find a way to stave off Jack Frost for a while before he ends our gardening season. You can improve the odds and extend the frost-free date: simply cover plants to retain heat and keep out cold.

Cold frames, greenhouses, and hoop houses are great protectors against the elements, but these semipermanent structures are not easily portable. For long rows of lettuce or greens, plastic row covers or floating row covers offer sufficient protection. If you have only a few tender basil plants or a prized hot pepper, you can simply throw a blanket over them, but a more effective way to keep them growing is to cover them with an individual plant protector, often called a cloche.

Cloches Up Close

Cloche (pronounced kl-osh) is the French word for “bell.” The original cloches were large bell-shaped jars that 19th-century French market gardeners placed over plants in spring and fall to act as portable miniature greenhouses. At one time, these glass jars covered acres of fields outside Paris that supplied out-of-season vegetables to the city’s households and restaurants. European gardeners also used barn-shaped glass cloches such as my favorite, the Chase cloche. These once popular cloches were constructed of panes of glass held together by cleverly crafted wires. They could be attached end to end to form a tunnel and cover rows of plants. Unfortunately, the glass barn cloches are no longer available, but home gardeners can use less elegant plastic row covers to fulfill the same function.

The classic glass bell jars are still available but have some significant limitations. Because they are made from heavy glass and are small, the air trapped within can quickly get too hot on sunny days and possibly kill plants. Pay close attention to ventilation. A professional gardening friend, trained in France, tells of trudging out to cloche-covered fields on bright, frosty mornings to slide a block of wood under one side of each cloche to vent it during sunny days. He’d return in late afternoon to kick out the blocks, so the cloches would sit flat on the ground and seal in the warm air for the night.

Although modern versions of these individual cloches are not as elegant as the traditional glass bell jars, some offer the same or a better degree of frost protection, are made of lightweight materials, and are easier to vent. Some are also convenient to store. Types of cloches range from those you can make from plastic milk jugs to elegant lantern cloches:

  • Solar umbrellas fold and unfold for easy storage. The spike handle holds the umbrella in place, and its height can be adjusted for venting.
  • The lantern cloche is made of an aluminum frame and double-walled, rigid plastic for optimum durability. The pyramidal top can be set ajar for venting.
  • A plastic version of the traditional glass jar cloche, the solar bell is lightweight, durable, and inexpensive.
  • Utilitarian plastic milk jugs with the bottoms cut out are vented by opening the lid. However, they offer only a few degrees of frost protection.
  • The plastic grow dome is sold as two halves that snap together. It’s easily vented by snapping open the holes on the top.
  • The tomato plant cover has a clear plastic top that snaps on for frost protection and can be removed for venting. It needs support in high winds.

Cloche Considerations

In my garden, I use cloches in many ways. Obviously, they provide great protection for any newly planted seedlings, but they also protect mature plants in fall. My bell-shaped glass cloche offers winter protection to my one sea kale (Crambe maritima), a perennial that is both ornamental and edible but borderline hardy in my garden. Where the climate is too cool to ripen peppers or eggplants, they can bask all season long in a large lantern cloche.

When selecting a cloche, one point to consider is how airtight it is. The less permeable a cloche is, the warmer the trapped air remains on cold nights. On the other hand, airtight cloches demand more attention to prevent overheating and possible death to your plants. I generally opt to forgo a few degrees of cold protection for the freedom of leaving my cloches almost unattended. This means leaving a block that vents an individual cloche in place overnight or leaving the top open.

If you live in snow country and are planning to protect vegetables well into winter, also consider how well your cloches will stand up under the weight of snow. Waxed-paper Hot Kaps will be crushed in a snowstorm, whereas glass or rigid plastic cloches such as the Aqua Dome can withstand an early winter snow.

Consider also the material from which the cloche is made and its durability. Some cloches, such as Hot Kaps, last only one season. Lightweight plastics used to make Wall O’ Waters, solar umbrellas, and tomato plant covers may last up to five years with proper care. Rigid polycarbonate plastics used to make the Aqua Dome and lantern cloches should last for many years, especially if the plastic has been treated with ultraviolet light inhibitors and the cloche is stored indoors out of the sun when not in use. Glass is forever — if it doesn’t crack first.

Finally, consider what you’ll do with the cloches when they’re not in use. If your garage is like mine, it’s already overflowing with shovels, flats, rakes, and other garden-related items. You might not want to figure out what to do with a gardenful of glass bell jars. Hot Kaps, on the other hand, get tossed out after only one season. Rigid plastic cloches such as solar bells and Aqua Domes can be stacked. Wall O’ Waters collapse when drained, solar umbrellas fold up like an umbrella and tomato plant covers unfold and store flat.

Visit the web site of garden consultant and writer Lee Reich at www.woodstocktimes.com/garden.htm.

What do a stylish woman’s hat and a tool to extend your garden’s growing season have in common? The answer: Both are cloches. If you’re a fan of 1920s period dramas (think “Downton Abbey”) then you’ve seen women wearing cloche hats that mold around the head in an elegant bell shape. A garden cloche is a slightly less elegant device, though worthy in its own right, that covers plants and allows you to extend your growing season by creating a warmer micro-climate.

A short history lesson

Cloche (kl-osh, pronounced like gauche or skosh) is a French word that means bell. Centuries ago, they were made of glass and looked like bell jars. Just like today, gardeners placed the cloche over individual plants to extend the growing season by protecting them from cold temperatures. Although they were very elegant, the problem with these glass cloches is that they often got too hot and baked the tender plants that they were covering. Therefore, gardeners had to prop them up with a small piece of wood to allow for ventilation.

Reportedly, these glass cloches can still be found at flea markets; I’ve never been lucky enough to find one.

What a cloche is NOT

A cloche is similar to, but not the same as, a greenhouse, a hoop house, or a cold frame. The commonality is that all of these devices extend your garden’s growing season. The differences aren’t so clear-cut, but (very) broadly speaking a cloche is smaller. Because of its small size, it is more portable but won’t cover as many plants.

Why you want a cloche

If you live in an area of the country that has cool weather, you want a cloche to extend your growing season. You can count on getting a few weeks at the beginning and end (spring and fall) of your growing season with a cloche. For gardeners in any climate, a cloche will help prevent heavy rain and wind from beating on your plants.

Many different options

Over the years, gardeners have been creative and developed a variety of cloche options. Bear in mind that because of their smaller size, it may take a number of cloches to protect your garden plants. Count on one cloche protecting one to three plants. Here are the most popular options:

Umbrella cloche

These funky contraptions are exactly what their name suggests. They’re clear plastic umbrella-shaped plant coverings that have a center rod (just like an umbrella) that roots the cloche in the ground. They’re great because they’re light weight, portable, and usually have ventilation. The downside is that I’ve only ever seen them available to buy online.

Tent cloche

A tent cloche looks a lot like a pup tent with two angled sides that meet at a center point; the ends are open to allow for ventilation. They are a great option because you can easily make your own. If you have two old windows hanging around, prop them up against a center pole to make a recycled tent cloche. Alternatively, pound two pieces of wood (3-4 feet long) in the ground a couple feet apart and drape a piece of clear plastic over to make a cloche; anchor the plastic to the ground with a couple stones.

Tunnel cloche

A tunnel cloche bears so much resemblance to a hoop house that I have a hard time telling them apart.

You can make your own out of plastic PVC pipe and clear plastic covering. Check out this guide for detailed instructions. I’ve seen some gardeners use cedar branches instead of PVC pipe, which is a nifty idea because it’s cheaper (if you have a cedar tree) and biodegradable.

Barn cloche

A barn cloche is a more elaborate type of cloche that looks a lot like a small greenhouse. They vary in size, but I think of them as a greenhouse that an American Girl doll (18 inches tall) might use. Find them at a garden store or through online retailers; many come in ready-to-assemble kits.

Reused plastic packaging cloche (a.k.a. down-and-dirty keep-it-simple cloche)

For years I’ve had a love-hate relationship with those plastic boxes that my baby greens came in. I loved that they protected my greens, but I hated the plastic that was used. Now, I have a better relationship with them because I reuse them to cover my most tender garden plants. Use garden stakes to secure them to the ground, or a couple of rocks placed on top will do the trick.

Another option is to cut the bottom off of a plastic gallon milk jug. I’ve even heard of some folks using an empty plastic peanut butter jar as a cloche. (Make your dog happy and let her lick the inside clean.)

Related on Organic Authority

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photo of garden cloche via

What Are Cloches And Bell Jars: How To Use Cloches In Gardens

Sylvia Plath knew what they were, but I think her bell jar was more of a confining and suffocating item, whereas in reality they are shelter and protect tender or new life. Bell jars and cloches are invaluable objects for the gardener. What are cloches and bell jars? Each is designed to go over plants to keep them warm, protect them from snow and ice, and act as a mini greenhouse. Cloches in gardens allow northern gardeners to start plants early. There are many aspects on how to use cloches and bell jars in the garden.

What are Cloches and Bell Jars?

Garden cloches are the fancy term for a glass dome that you place over plants sensitive to cold. The word actually means bell in French. The glass enhances the light and heat for the plant and protects it from direct contact with snow or ice. These are most useful for small plants and starts.

A bell jar is basically the same item, but fans out slightly wider at the base and has a handle at the top. The original bell jars had handles of blown glass, but this focused the sunlight with laser-like intensity and most gardeners soon lopped off the handle. Flower bell jars with glass handles are a thing of the past, as most have been replaced with wood or even plastic handles.

Bell Jars and Cloches in Gardens

These protective caps are useful in many garden situations. Young seedlings covered by bell jars or cloches are protected from cool spring weather, which means you can start them outside even when the soil hasn’t warmed up all the way.

Garden cloches are also handy to overwinter slightly sensitive plants. Although the original cloches were glass domes, you can make something similar with plastic and a wire form. The idea is to focus sunlight’s heat and light so your veggies get an early start or that favorite plant overwinters successfully.

They also increase early blooming in plants that usually don’t flower until after all danger of frost has passed. Flower bell jars allow tender summer flowers to grow up to four weeks earlier in the season.

How to Use Cloches and Bell Jars

You can purchase the expensive blown glass covers, or you can use the plastic cells that you fill with water. These perform the same function and are an inexpensive cloche that still lets plants grow in cool season temperatures. You may also use milk jugs with the bottom cut out.

Make sure you put whatever type of cover you choose over the plant early. Watch the forecast or just keep plants covered with garden cloches in zones where freezing temperatures and a short growing season are the norm.

Common plants to start in a cloche are tomatoes, peppers and tender herbs, like basil. Exotic plants also benefit from snuggling under a garden cloche.

Watch for high temperatures and vent the cloche to prevent the plant from literally cooking. When sun is hot and high, prop up the edge of the cloche with a stick or something to allow excess hot air to escape.

Cloche/Bell Jars

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