When Are Microgreens Ready to Harvest?

Knowing the right time to harvest microgreens is more nuanced than it first appears. Harvest too early and the shoots are underdeveloped, with lower nutritional content and less flavour. Harvest too late and the texture becomes tougher, the flavour can become bitter, and the shoots begin to divert energy to first true leaf production — a process that softens the cotyledons (seed leaves) and reduces overall quality. The ideal harvest window is typically only 2 to 4 days wide, so knowing what to look for matters.

The Cotyledon Stage — The Universal Harvest Signal

For the vast majority of microgreens, the correct harvest time is when the cotyledons (seed leaves) are fully open and the first true leaves are just beginning to appear as tiny points between the cotyledons. Cotyledons are the first leaves that emerge from a seedling — they look different from the plant's eventual true leaves and are usually rounder, simpler in shape. At this stage, the shoot has converted fully from seed-stored energy to photosynthetic energy, and nutrient concentration is at its peak.

You do not need to wait for true leaves to develop fully. In fact, leaving the tray until true leaves are large and well-developed often results in a tougher, slightly more bitter product. The window between "cotyledons fully open" and "first true leaves starting to emerge" is when to cut.

Harvest Timing by Common Variety

Radish: 6 to 8 days. Ready when cotyledons are open and stems have taken on their characteristic pink or red colour. Broccoli: 7 to 10 days. Cotyledons fully open, shoots 4 to 6 cm tall. Sunflower: 10 to 14 days. Cotyledons open and lifted free of any remaining seed hulls. Pea shoots: 10 to 14 days, but can be harvested at any height between 8 and 15 cm — this is a personal preference crop. Basil: 12 to 16 days. Cotyledons fully open, first set of true leaves just beginning. Wheatgrass: 7 to 10 days after germination, when the grass is 15 to 20 cm tall and before the second blade develops.

Visual Signs the Tray Is Ready

Look for: cotyledons that are fully open and standing flat (not curled or partly closed), a uniform green colour throughout the canopy (no yellow patches), and stems that are upright and firm. If the canopy is leaning significantly toward the light, rotate the tray 180 degrees and allow an extra day for the shoots to straighten before harvesting. The tray should smell fresh and green — a slightly earthy, grassy aroma is normal. Any sour, fermented or musty smell indicates a problem and the tray should be inspected carefully before consuming.

What Happens If You Wait Too Long

Beyond the ideal harvest window, microgreens begin to develop first true leaves at the expense of cotyledon quality. The stems may become slightly hollow or pithy, the flavour can intensify to the point of harshness in brassicas, and the texture of the seed leaves becomes tougher. For most varieties, waiting 3 to 4 days past the ideal harvest window is noticeable but the crop is still edible. Waiting a week past the ideal window typically produces a crop that is still safe to eat but noticeably inferior in every quality measure.