Cilantro (Coriandrum sativum) readily reseeds itself in garden environments. This annual herb is cultivated globally, serving a dual purpose: its leaves are used fresh, and its dried seeds are known as the spice coriander. This natural tendency for self-propagation allows the plant to appear year after year without direct human intervention.
The Cilantro Life Cycle and Seed Production
Cilantro initiates the process of reproduction, known as bolting, when temperatures rise significantly or when the plant reaches full maturity. Bolting is the rapid transition from producing leafy growth to developing a central flower stalk. This change is often triggered by soil temperatures consistently exceeding approximately 75°F (24°C), signaling the end of the plant’s vegetative phase.
Small, delicate white or pink flowers appear on the stalk and must be pollinated to develop fruit. Following successful pollination, the flowers mature into small, round, green fruits containing the seeds (coriander). The plant directs energy into filling these fruits for the next generation.
As the seeds ripen, they turn a beige-brown color and begin to dry out while still attached to the plant. When fully mature, the dried seed casings naturally shatter or drop directly onto the soil surface below the parent plant. This dispersal mechanism ensures a new generation of seeds is deposited exactly where the previous plant successfully thrived.
Conditions Required for Spontaneous Germination
Although seeds drop in the summer heat, they typically do not sprout immediately due to natural dormancy. This ensures the seeds wait for more favorable conditions rather than attempting to sprout during the intense heat that caused the parent plant to bolt. The seeds delay germination until certain environmental cues are met.
Spontaneous germination is highly dependent on cooler soil temperatures, specifically within a range of about 55°F to 70°F (13°C to 21°C). Seeds dropped in mid-summer usually remain dormant until the cooling temperatures of late autumn or early spring arrive. This requirement explains why cilantro often appears unexpectedly as a “volunteer” plant during the shoulder seasons.
Adequate soil moisture is another necessary trigger for breaking seed dormancy and initiating sprouting. A light, consistent presence of water is needed to soften the hard seed coat and activate the embryo. Heavy rainfall or consistent irrigation combined with the correct temperature range reliably leads to a high rate of germination.
Utilizing and Controlling Volunteer Cilantro
The resulting spontaneous seedlings, often called volunteer cilantro, can be utilized for continuous leaf production. Gardeners should identify clusters and thin them out to ensure proper spacing, typically 6 to 8 inches (15 to 20 cm) between plants. Thinning allows the remaining seedlings adequate access to light, nutrients, and air circulation, promoting robust leaf growth.
Volunteers provide a natural method for succession planting, ensuring a continuous, staggered harvest throughout the cooler growing seasons. By allowing a small patch of the parent plant to drop seeds, a new crop of young cilantro is established without the need for manual planting. This passive method saves time and effort while maximizing garden space use.
For gardeners seeking to prevent unwanted reseeding, the most effective method is harvesting the seeds before they fully mature and drop. The seed heads should be clipped while still green and allowed to dry in a controlled environment, such as a paper bag. This preventative step removes the source of future volunteer plants.
When volunteers sprout in inconvenient locations, they should be removed promptly to maintain garden order. Young cilantro seedlings are shallow-rooted and easily pulled or hoed from the soil surface. Removing these unwanted plants prevents competition with other cultivated crops for water and soil nutrients.