Microgreens are young, edible seedlings of vegetables and herbs harvested at a premature stage of development. These tiny plants are generally cut once their first leaves, known as cotyledons, have fully formed, but before they mature into full-sized plants. Unlike sprouts, microgreens require a growing medium and light, and only the stem and leaves are consumed. Understanding the specific timeline required to move from a dry seed to a harvestable, nutrient-dense green is the primary focus for any grower.
The Essential Timeline
The time microgreens take to reach the harvest stage depends highly on the seed variety, but the overall window typically falls between 7 and 21 days from seeding. This rapid turnover is a main appeal of microgreen cultivation. Growers categorize varieties based on their average growth speed to manage planting schedules efficiently.
The fastest growers, often ready for harvest in 7 to 10 days, include varieties like radish, broccoli, and most brassicas. These seeds germinate quickly and develop their cotyledons rapidly. Moderate-speed microgreens, such as sunflower and buckwheat, usually require 10 to 14 days to fully mature.
Slower-growing microgreens, which may take 14 to 21 days, include herbs like cilantro, basil, and beet greens. These species require a longer period to develop sufficient size and flavor complexity. Understanding this inherent variability based on seed genetics is the first step in predicting the total time investment.
Stages of Microgreen Development
The overall time to harvest is segmented into three distinct developmental phases, beginning with planting and germination. After sowing seeds onto the grow medium, many varieties enter a blackout period lasting 2 to 5 days. During this time, trays are covered and often weighted to mimic the soil environment, encouraging emerging stems to stretch and search for light.
This dark phase promotes stem elongation, resulting in taller, more tender microgreens. Once the seedlings have anchored their roots and the first sprouts are visible, they transition to the second phase: introduction to light. The cover is removed, and the plant begins photosynthesis.
The final phase is the photosynthetic growth period, where the cotyledon leaves fully expand and turn deep green. This stage maximizes biomass and nutrient concentration under direct light. The entire timeline is a sequential biological process where successful germination dictates the speed of leaf development.
Variables Influencing Growth Speed
While the genetic timeline provides a baseline, several environmental factors can accelerate or slow the growth rate. Temperature is a significant regulator of plant metabolism, with warmer conditions promoting faster germination and growth. Maintaining an optimal temperature, often between 65°F and 75°F, can shave days off the overall harvest time.
Light quality and intensity are important once the blackout period concludes. Providing sufficient light, often through specialized LED grow lights, ensures cotyledons rapidly develop the chlorophyll needed for efficient photosynthesis. Insufficient light results in pale, “leggy” seedlings that stretch excessively and are structurally weak.
Preparation for certain seeds can influence the initial germination speed. Larger seeds with hard hulls, such as peas and sunflowers, benefit from soaking for 8 to 12 hours before planting. This process, known as imbibition, jump-starts the water absorption necessary for the seed to break dormancy and begin germination sooner.
Knowing When and How to Harvest
The growth timeline concludes when microgreens display the correct visual cues, typically when the cotyledons are fully unfurled and vibrant. For many varieties, the window of optimal harvest is just before or as the first set of true leaves begins to emerge. True leaves look like miniature versions of the mature plant’s foliage and signal a change in the plant’s nutritional profile and texture.
Harvesting at the correct stage ensures maximum flavor and nutritional density. The technique for harvesting is simple, involving a clean, sharp knife or scissors to cut the stems. The cut should be made just above the soil or growing medium line to avoid transferring residue to the edible portion.
Cutting the microgreens cleanly prevents damage to the delicate stems and keeps the harvested greens fresh. This action marks the end of the growth cycle, providing a ready-to-use crop that can be immediately consumed or stored. The entire tray is harvested at once, as microgreens do not regrow significantly after being cut.