What Is a Cloche? Meaning, Types and How It Protects Plants
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What is a cloche? It is a cover placed over a plant or a small group of plants to protect it from cold air, wind and some pests. The original cloche was a bell-shaped glass dome. Today the term covers a wider set of objects, including plastic covers for a single plant and larger movable covers built over several plants. This page explains what a cloche is, how it changes the air around a plant, what types gardeners use, and where its protection stops.
Quick answer
- A cloche is a cover placed over individual plants to shelter them from wind and cool temperatures.
- Penn State Extension says traditional cloches were glass, bell-shaped coverings, and that the term now also includes plastic covers and movable multi-plant coverings.
- Iowa State University Extension says a cloche only provides frost protection down to about 29 or 30 degrees Fahrenheit.
- A cloche works by holding warm air close to the plant, so it needs ventilation on sunny days to avoid overheating.
What a cloche is
A cloche is a cover, not a container. It sits over the plant and creates a small space that stays warmer and calmer than the open garden. Penn State Extension describes the purpose plainly: a cloche is used to create a space that will protect tender plants from cold temperatures. Its job is to slow the loss of heat and reduce the force of wind, which the Iowa State source ties to young transplants.
The name has been stretched over time. Penn State states that traditionally cloches were glass, bell-shaped coverings placed over individual plants. It adds that the term has been expanded to include individual coverings made from plastic. It also notes that the term now includes movable, multi-plant coverings, which may be built from wood, fabric or other materials. Iowa State University Extension uses a different set of names for the same idea. Its guidance says covers placed over individual plants are often called hot tents, hot caps or cloches.
How a cloche protects a plant
The main mechanism is heat retention combined with wind protection. Sunlight passes through the cover and warms the soil and air under it. The cover then limits how quickly that warm air escapes. Iowa State states that cloches protect young transplants from wind and cool temperatures. The protection is local: the warmth applies to the space under the cover, not to the surrounding garden.
Because the air under the cover heats quickly, a cloche can also become too warm. Iowa State notes that decorative and functional bell-shaped glass or plastic cloches can provide warmer temperatures for plants under them. A gardener who uses a cloche on a sunny day should check for heat buildup and open the cover, lift one side, or remove it when the air inside becomes too warm for the plant.
Types of cloche
The sources describe three broad groups. The first is the classic glass dome, which is traditionally bell-shaped. The second is the individual plastic cover for a single plant. The third is the movable, multi-plant cover, which Penn State says may be built from wood, fabric or other material.
Iowa State’s examples include milk jugs with the bottom removed as a simple homemade cover for a single plant. The sources do not rank these types by performance, so a grower should choose based on the plants, the weather and how easily the cover can be placed and removed.
Frost limits and what a cloche cannot do
A cloche has limits. Iowa State University Extension says that covers placed over individual plants only provide frost protection down to 29 or 30 degrees Fahrenheit. A cover that protects against wind and mild cold will not necessarily keep a plant alive in a hard freeze. A grower who expects colder weather than the cover can handle should add other protection.
Penn State lists cloches with other season extenders, including low tunnels, cold frames and hot beds. These structures are larger than a cloche and can cover a bed or a row. A cloche is best understood as the smallest of these tools. It suits a few plants, a short period of cold weather, or a transplant that needs help getting established.
How to use a cloche in a home garden
A basic approach starts with placing the cover over a plant after planting or transplanting. The cover should be anchored so wind does not lift or move it. On sunny days, the grower should check the air inside and provide ventilation before the plant overheats. Once the weather warms and the plant begins to outgrow the cover, the cover can be removed. These steps follow from the mechanism: a cloche traps heat and blocks wind, so it helps most during cold, windy periods and can harm a plant when the trapped heat is not released.
For more on early-season planting, see how to grow dill from seed and how to grow celery from seed. For a general overview of growing food plants, see how to grow microgreens.
How we chose
The sources were chosen from university extension websites that describe season extension and cover types. Two pages were opened and checked for HTTP 200 on 2026-10-27. The Penn State Extension article was chosen for its definition and its list of cloche forms. The Iowa State University Extension page was chosen for its description of protection limits and its alternative names. Retail product pages were not used for any claim in this article.
What we could not verify
The two extension pages describe cloches in general terms. They do not compare individual products, and they do not measure how much warmer the air under a given cover will be on a particular day.
What the sources do not say
The sources do not give a single temperature gain for all cloches, and they do not state how long a cover can safely remain on a plant during a warm spell. They also do not provide a complete list of materials or a sizing guide. Readers should treat the frost limit as the source describes it and check local weather before relying on any cover.
Frequently asked questions
Is a cloche the same as a row cover?
Not necessarily. Penn State Extension groups cloches with low tunnels and cold frames, which are season extenders that can cover larger areas. The two sources checked for this article do not compare cloches with row covers directly.
What did the original cloche look like?
Penn State Extension states that traditionally cloches were glass, bell-shaped coverings placed over individual plants.
Can a cloche protect plants from a hard freeze?
Iowa State University Extension says covers placed over individual plants only provide frost protection down to 29 or 30 degrees Fahrenheit. A harder freeze needs more protection.
Why can a cloche make a plant too hot?
The cover traps sunlight and warm air. Iowa State notes that cloches can provide warmer temperatures for plants under them, so ventilation is needed on sunny days.
Are homemade cloches a real option?
Iowa State University Extension lists milk jugs with the bottom removed as one of the easiest hot tents for a home gardener to use, which is a similar cover idea.
Sources
- Penn State Extension, “Season Extenders and Growing Fall Vegetables”: https://extension.psu.edu/season-extenders-and-growing-fall-vegetables (opened 2026-10-27)
- Iowa State University Extension and Outreach, Yard and Garden, “Tips for Earlier Yields in the Home Vegetable Garden”: https://yardandgarden.extension.iastate.edu/how-to/tips-earlier-yields-home-vegetable-garden (opened 2026-10-27)
