Most microgreens are ready to harvest 7 to 14 days after sowing. Fast brassicas such as radish and broccoli can be cut in a week, while slow herbs such as basil and cilantro take three weeks or more. The chart below gives typical timings for 16 popular crops, followed by the factors that make your trays faster or slower.
Days-to-harvest chart
Days are counted from sowing, at a room temperature of roughly 65–75°F (18–24°C).
| Crop | Germination | Blackout | Harvest | Speed |
|---|---|---|---|---|
| Radish | 1–2 days | 3 days | 7–12 days | Fast |
| Wheatgrass | 1–2 days | 2–3 days | 7–10 days | Fast |
| Broccoli | 2–3 days | 3–4 days | 8–12 days | Fast |
| Kale | 2–3 days | 3–4 days | 8–12 days | Fast |
| Kohlrabi | 2–3 days | 3–4 days | 8–12 days | Fast |
| Mustard | 1–3 days | 3 days | 8–12 days | Fast |
| Arugula | 1–3 days | 3 days | 8–12 days | Fast |
| Red cabbage | 2–3 days | 3–4 days | 8–14 days | Fast |
| Sunflower | 2–3 days | 3–4 days | 8–12 days | Fast |
| Pea shoots | 2–3 days | 3–5 days | 10–14 days | Medium |
| Amaranth | 2–4 days | 3–4 days | 10–14 days | Medium |
| Beet | 4–5 days | 4–6 days | 12–18 days | Slow |
| Swiss chard | 4–5 days | 4–6 days | 14–20 days | Slow |
| Cilantro | 5–10 days | 5–7 days | 16–21 days | Slow |
| Basil | 4–6 days | 4–5 days | 16–25 days | Slow |
| Parsley | 7–14 days | 6–8 days | 21–28 days | Very slow |
These numbers are typical ranges, not guarantees. Seed variety, freshness and temperature can shift them by a few days either way. For seed amounts for each crop, see our seed density chart.
How to tell when microgreens are ready
The calendar is a guide; the plants tell you when they are ready. Harvest when:
- The cotyledons (the first pair of leaves) are fully open and flat.
- The stand has reached 1.5–3 inches (4–8 cm) for most crops, or 3–6 inches for pea shoots and wheatgrass.
- The first true leaf is just starting to appear between the cotyledons — or before it does.
Waiting too long has a cost. Once true leaves grow, most microgreens become tougher, and some change flavor: sunflower becomes noticeably bitter, and radish gets very hot. If you cannot eat a tray at its peak, you can harvest and refrigerate it for several days.
What makes microgreens grow faster or slower?
Temperature
Germination is the stage most affected by temperature. Most microgreens germinate best when the growing medium is about 65–75°F (18–24°C). In a cold winter room at 60°F (15°C), germination can take twice as long. A seedling heat mat under the tray during blackout can help, but remove it once the seedlings are up, because warm, humid trays encourage mold.
Seed freshness
Old seed germinates slowly and unevenly. If a tray that should be up in two days takes five, test your seed: put 20 seeds on a damp paper towel in a sealed bag and count how many sprout in three days. Below 80% germination, replace the seed. More causes are covered in microgreens not germinating.
Soaking
Soaking big seeds — peas, sunflower, wheat — for 8–12 hours speeds up germination by a day or more and makes it more even. Small seeds do not need it. See soak times by seed.
Light
Under strong light, microgreens grow compact and green but may take a day longer to reach full height. In weak light they stretch faster but are pale and floppy. Aim for 12–16 hours under a light hung a few inches above the tray; our grow light guide has the details.
Blackout length
A slightly longer blackout (an extra day or two) makes taller, more uniform stems, which some growers want for crops like cilantro and amaranth. Too long, and seedlings become weak and yellow. The blackout guide explains the trade-off.
Planning a steady supply
Because each crop has a predictable timeline, it is easy to plan for fresh greens every week:
- Pick your harvest day. For example, Saturday.
- Count back from the chart. Radish takes about 8 days, so sow it on the Friday of the week before. Pea shoots take about 12 days, so sow them on the Monday of the week before.
- Sow small amounts often. Two smaller trays sown four days apart give a more even supply than one big tray every week.
- Mix speeds. A fast crop (radish), a medium crop (peas) and a slow crop (basil) started on the same day give you three harvests spread over two weeks.
| If you want to harvest on day… | Sow radish on day | Sow peas on day | Sow basil on day |
|---|---|---|---|
| 14 | 6 | 2 | — |
| 21 | 13 | 9 | 0 |
| 28 | 20 | 16 | 7 |
Frequently asked questions
What is the fastest microgreen to grow?
Radish is usually the fastest, often harvestable in 7–8 days. Wheatgrass, mustard and arugula are close behind.
Why are my microgreens growing so slowly?
The usual causes are a cold room, old seed, a growing medium that is too dry or too wet, or weak light. Start by checking the temperature of the room where the tray sits.
Can I harvest microgreens early?
Yes. As soon as the cotyledons have opened, microgreens are edible. Harvesting a little early gives a milder, more tender result and less yield.
How long can I leave microgreens before harvesting?
Most can stay on the tray for a few extra days, but quality drops once true leaves form. The tray also uses up the seed’s stored energy, so leaves may start to yellow after about three weeks without fertilizer.
