Cilantro (Coriandrum sativum) is an annual herb known for its bright, citrusy leaves used in many global cuisines. While it is a cool-season plant that thrives in moderate temperatures, it is not naturally equipped to survive the deep cold of a true winter without significant intervention. The ability to harvest cilantro during the winter months depends entirely on the grower’s location and the techniques used to shield the plant from harsh weather conditions.
Cilantro’s Seasonal Growth Cycle
Cilantro flourishes in a narrow temperature range, performing best when temperatures are consistently between 50°F and 70°F, which typically occurs in the spring and fall shoulder seasons. When temperatures exceed 75°F, the plant responds by entering a reproductive phase known as bolting. Bolting causes the plant to rapidly send up a flower stalk, producing seeds (coriander), and fundamentally changes the leaf structure and flavor. The leaves become smaller, more feathery, and develop a bitter taste, making them less desirable for culinary use.
When cold weather approaches, cilantro’s growth slows, but it remains one of the more cold-tolerant herbs. The plant can withstand a light frost and may even survive short drops in temperature down to about 20°F. However, prolonged exposure to temperatures below freezing will damage or kill the leaves, and an extended hard freeze will destroy the entire plant. In mild climates, cilantro can provide leaves throughout the winter, but in colder regions, it enters a semi-dormant state and requires protection to maintain a winter harvest.
Techniques for Extending the Winter Harvest
Gardeners in regions with moderate winters can extend their harvest by using outdoor coverings that create a protective microclimate. Low tunnels, row covers, or cloches placed over the plants can elevate the temperature around the foliage, shielding the plants from the most damaging frosts. These structures also help to retain ground heat and break the wind, allowing the cilantro to continue slow growth even as ambient temperatures drop toward freezing. A cold frame, which is essentially a bottomless box with a transparent lid, offers the most robust passive protection for cilantro grown outdoors during winter.
For a guaranteed supply of fresh leaves in colder climates, the most reliable method involves moving the cultivation indoors before the first hard freeze. Cilantro is well-suited for container growing, but it should be planted directly from seed in the pot, as the plant’s deep taproot does not transplant well. A pot with a depth of at least six to eight inches allows the root system to develop properly. The plant thrives in an indoor environment that stays relatively cool, ideally between 60°F and 70°F, which helps to prevent premature bolting.
To replicate light conditions, the pots should be placed in a south-facing window to maximize sunlight exposure. Since natural light is often insufficient during winter, supplemental lighting is required to encourage leafy growth. Full-spectrum LED grow lights positioned six to twelve inches above the foliage and kept on for 10 to 14 hours daily will provide the energy needed for photosynthesis. Indoor air is often very dry, which can stress the plant, so occasional misting or using a humidity tray can help replicate the moist conditions cilantro prefers.
Post-Harvest Storage Methods
When a hard freeze is imminent or when an indoor harvest is abundant, proper storage ensures the leaves remain flavorful for later use. For short-term storage, the “bouquet” method treats the herb like a cut flower. The stems should be trimmed and placed in a glass jar with one to two inches of water, then loosely covered with a plastic bag to maintain humidity before being stored in the refrigerator. Changing the water every few days can keep cilantro fresh for up to two to three weeks.
For long-term preservation, freezing is preferred over drying, as drying cilantro often results in a significant loss of its distinct flavor. One common technique involves finely chopping the washed leaves and packing them into ice cube trays. The chopped cilantro is then covered with a small amount of water or olive oil before freezing. Once frozen solid, the cubes can be transferred to an airtight container or freezer bag, where they will maintain their flavor for several months and can be dropped directly into cooked dishes.