Microgreens in Ten Days: The Fastest Crop on Any Windowsill
No grow light, no drainage, no soil depth required. A step-by-step method for going from dry seed to a tray of microgreens in about ten days indoors.
Microgreens are the one indoor crop that works in a dim flat, in winter, with no equipment beyond a takeaway container. You harvest at the seed-leaf stage, which means the seed itself supplies most of the energy — the window only has to finish the job.
This article contains no affiliate links, which is why there is no disclosure box at the top. Everything here can be done with what is already in your kitchen.
What you need
- A shallow tray, 4–5 cm deep. A clean takeaway container works.
- A second tray or a plate to use as a lid.
- Enough compost to fill it 3 cm deep. Soil isn’t the only option here — see soil vs. hemp mat vs. paper towel if you’d rather skip the cleanup.
- Seed sold for sprouting or microgreens — radish, pea, sunflower, broccoli or mustard to start with. See which microgreens to grow first for how those (and a few others) compare on speed and flavor before you pick.
Day 0: Sow
Fill the tray with compost, level it, and firm it lightly. Scatter seed much more thickly than you would for a normal sowing — the surface should be almost covered, seeds nearly touching.
Do not cover with compost. Mist thoroughly, then put the lid on.
Days 1–3: Blackout
Keep the tray covered and out of the light. Darkness makes the stems reach, which is exactly what you want here — long stems are easier to cut.
Mist once a day. The compost should be damp, never sitting in water.
Days 4–5: Uncover
When most seedlings have lifted the lid slightly, take it off and move the tray to your brightest window. The stems will be pale yellow; they green up within a day.
Rotate the tray daily or everything leans toward the glass.
Days 6–10: Grow on
Water from the base if you can — pour a little into an outer tray and let the compost draw it up. Overhead watering at this density invites mould.
Harvest
Cut with scissors just above the compost when the first true leaves start to appear, usually day 8 to day 12 depending on the crop and the temperature.
Radish and mustard are fastest. Sunflower and pea take a couple of days longer and give you the most volume.
Do not try to regrow them
Unlike lettuce, microgreens do not come again. Tip the tray into the compost bin and sow the next one. Running two trays a week apart gives a continuous supply.
Troubleshooting
Fuzzy white growth on the compost — usually root hairs, not mould. Root hairs are fine, evenly spread around the stem base and disappear when misted. Mould is patchy, grey-green and smells. If in doubt, sow less thickly and improve airflow. See the full troubleshooting guide for how to tell the two apart with confidence, plus fixes for leggy stems and patchy germination.
Seeds that never germinate — old seed, or the tray dried out during the blackout period.
Pale, floppy greens after uncovering — the window is too dim. They are still edible; just expect a milder flavour.
Where to go next
Once the rhythm clicks, microgreens are the cheapest fresh green you can produce indoors. When you want something that keeps cropping instead of being resown, move on to cut-and-come-again lettuce.
Filed under Microgreens. Questions or a correction? Get in touch.
Keep reading
Which Microgreens to Grow First: 7 Varieties Compared
Radish, broccoli, mustard, sunflower, pea shoots, kale and arugula microgreens compared by days to harvest, pre-soak needs and flavor, so you know which seed to buy.
Moldy, Leggy or Not Germinating: Fixing Common Microgreens Problems
How to tell mold from harmless root hairs, why microgreens turn pale and leggy, and what causes patchy germination — with a fix for each.
Soil vs. Hemp Mat vs. Paper Towel: The Best Growing Medium for Microgreens
Comparing the three most common ways to grow microgreens indoors — mess, moisture control, reuse and typical cost — so you can pick the right one for your tray.