Collard greens (Brassica oleracea) are a highly popular leafy vegetable prized for their robust flavor and ability to withstand cold temperatures. This cool-season crop is a relative of cabbage and kale, cultivated for its large, edible leaves. The time required to grow collard greens from planting to the first substantial harvest spans 50 to 85 days, depending on the starting method and the specific cultivar chosen.
The Collard Greens Growth Timeline
Starting collard greens from seed requires the longest time commitment before harvesting can begin. Seeds typically germinate within a four to ten-day window when provided with an optimal soil temperature of around 75°F. Gardeners starting plants early in the spring often sow these seeds indoors four to six weeks before the last expected frost date to give them a head start.
Once the young plants are transplanted into the garden, they require an additional period of growth before the leaves are mature enough to pick. Varieties bred for quick production, like certain hybrids, may be ready in as few as 60 days from the initial seeding. However, many traditional heirloom types take a longer 75 to 85 days to reach full maturity, resulting in larger, more robust leaves.
The quickest path to a harvest is using nursery-bought transplants, which bypass the initial indoor growth period. Starting with established transplants significantly reduces the time to the first harvest to approximately 40 to 50 days. While full maturity marks the point for harvesting the entire plant, individual leaves are often ready for picking much sooner.
Key Environmental Factors Influencing Growth Speed
The speed of the collard greens growth cycle depends on environmental variables. Temperature is a factor, as collards thrive in cooler conditions, optimally between 55°F and 75°F. Exposure to sustained high temperatures is a stressor that can cause the plant to “bolt,” or prematurely send up a flower stalk and produce seeds.
Bolting redirects the plant’s energy away from leaf production, resulting in slower growth and a bitter, tougher texture in the remaining leaves. Inconsistent or insufficient access to nutrients will slow the rate of growth. Collard greens are known as heavy feeders, requiring ample nitrogen to fuel the rapid production of large, tender green leaves. A lack of nitrogen is signaled by chlorosis, a condition where the leaves turn yellowish between the veins, and this deficiency will stunt the plant’s development.
Consistent moisture is necessary for maintaining a steady, fast growth rate. The plants need about one to two inches of water per week; drought conditions will quickly lead to wilting and severely impede the development of new foliage.
Harvesting Techniques and Extending the Season
The timing of the harvest begins once the leaves are about 6 to 10 inches long. Harvesting the leaves while they are still young and tender prevents them from becoming overly tough or developing a strong, slightly bitter flavor. This initial harvest can often occur before the plant reaches its full maturity date.
To maximize the yield from each plant, the preferred technique is the “cut-and-come-again” method, which allows for continuous leaf production. This involves selectively removing the largest, outermost leaves from the plant. It is important to leave the inner six to eight leaves intact, along with the central growing point, or terminal bud, so the plant can continue to generate new foliage. This method extends the harvest season for months beyond the initial maturity date.
Collard greens have an enhanced flavor profile following exposure to a light frost. The cold temperature triggers a protective response, causing the plant to convert stored starches into simpler sugars, which results in a noticeably sweeter, milder taste.