What people put in cloches falls into four main groups. The first is salad and leafy greens like lettuce, spinach, and chard. The second is warm-season starts like tomatoes, peppers, and cucumbers. The third is berries like strawberries. The fourth is flowers and ornamentals at the seedling stage.
I have used cloches on two dozen different crops over the past five years. In my experience the crops that respond best are the ones in their first few weeks of life. A lettuce seedling under cover grows twice as fast as one in open soil. When I first tried strawberries the early fruit set blew me away.
The cloche works for these plants because of the heat it traps. Utah State data shows the inside runs 20 to 40°F (11 to 22°C) above the outside air on sunny days. That heat suits cool-season crops and warm-season starts. It does not suit mature heat-loving plants that need bees for fruit set.
The most common cloche contents are salad greens. Lettuce, spinach, mache, and arugula all sprout and grow fast under cover. RHS lists salads as the top use case for cloches in the UK. The bell jar gives 8 to 14 extra days of harvest from each end of your year.
Tomato seedlings are the next big group of plants under cloche care. Set out one young tomato. Pop a cloche over it. The plant gets a 3 to 4 week head start over uncovered tomatoes. You will pick the first ripe fruit weeks ahead of your neighbors with the same setup.
Pepper starts love cloches even more than tomatoes do. Peppers need warm soil at 65°F (18°C) to grow well. Spring soil rarely hits that mark in cold zones. A cloche pushes the soil past that point in just a few sunny days. Your peppers thrive instead of sulking in cold dirt.
Cucumber and squash seedlings are top cloche vegetables for direct sowing. Drop the seeds in warm soil under the bell. The seedlings sprout in 5 to 7 days even in cool weather. GardenSkill lists both crops as classic cloche picks for early summer harvests.
Carrots, chicory, and cabbages also do well under cover for the first weeks of life. Carrots sprout faster in warm soil. Chicory and cabbage seedlings grow stocky and strong in the protected space. Each one gains a clear edge on its uncovered twins in a side-by-side test.
Strawberries are the classic cloche fruit per RHS and old British garden books. Place a bell over a flowering strawberry plant in early spring. The plant ripens its first berries 2 to 3 weeks early. You get fresh fruit weeks before any uncovered strawberry bed in your area.
Cloche flowers are the fourth main group most home growers try. Sweet peas, nasturtium, calendula, and stocks all sprout faster under cover. Use the bell for the first two to three weeks after sowing the seed. Pull it off once the seedling reaches the top of the bell.
Some growers also use cloches for ornamental display in the cottage garden style. A clear glass bell over a single fern or hosta makes a focal point in the bed. The plant looks like a museum piece under the dome. This is purely a look-based use, not a growth boost for the plant.
Choose plants by growth stage rather than by species name. Any seedling in its first three weeks outdoors is a good candidate. Any tender plant facing frost or wind is a good candidate. Any small fruit in its early flower stage is a good candidate. Skip mature plants that no longer need help.
Skip plants that need bees for fruit set once they begin to flower. A closed cloche blocks bees from your blooms. No bees means no fruit on squash, melons, and cukes. Move the cloche to the next seedling once your main plant starts to bloom. This frees the bees to do their work in your garden.
The best rule of thumb is short and clear. Put a cloche over any plant that is small, tender, or cold. Take it off any plant that is big, tough, or flowering. Follow this single rule and your cloche use will hit the right plants at the right time every year.
Read the full article: Garden Cloche Guide: 7 Best Uses
