Microgreens are vegetable and herb seedlings harvested when they are only 1–3 inches tall, usually 7 to 21 days after sowing. They grow on a windowsill or a small shelf, need no garden, and one standard tray can give you several salads’ worth of fresh greens in about ten days.
This guide walks through the whole process for a complete beginner — what to buy, how much seed to use, the blackout period, watering, light and harvest — with the numbers you need at each step.
Key takeaways
- Start with radish, broccoli or pea shoots. They are fast and forgiving.
- Use a tray with drainage holes, 1–1.5 inches of moist potting mix or coco coir, and sow seeds densely in a single layer.
- Keep trays covered and dark for 3–4 days, then give them 12–16 hours of light a day.
- Water from below once the seedlings are up, and harvest with scissors just above the soil.
What you need to start
You can grow microgreens with very little equipment. Here is the short list, with the cheaper option in brackets.
| Item | Why you need it | Budget option |
|---|---|---|
| Shallow tray with drainage holes | Holds the growing medium | Clean takeaway container with holes poked in the bottom |
| Solid tray (no holes) | Sits under the first tray for bottom watering | Baking tray or a second container |
| Growing medium | Holds moisture for the roots | Seed-starting mix or coco coir |
| Seeds sold for microgreens or sprouting | Untreated seed, bought in bulk | A small 1 oz (28 g) packet to test |
| Spray bottle | Moistens the surface while seeds germinate | Any clean spray bottle |
| Light | Turns pale seedlings green and keeps them upright | A bright window; an LED shop light is better |
| Scissors | For harvesting | Kitchen scissors |
The most common tray is the “1020” tray, which measures about 10 × 20 inches. Seed amounts in most guides — including ours — are given per 1020 tray. If your container is smaller, use our seed calculator to scale the amount.
Always buy seed that is untreated. Seed sold for garden planting is sometimes coated with fungicide, which you should not eat. Packets labeled for microgreens or sprouting are untreated.
Step 1: Choose an easy first crop
Some microgreens are ready in a week; others take three and are fussy about moisture. For your first tray, pick one of these:
- Radish — germinates in 1–2 days and is ready in 7–12 days. Peppery and colorful.
- Broccoli — mild flavor, ready in 8–12 days.
- Pea shoots — large seeds that are easy to handle; ready in 10–14 days and sweet.
Leave basil, cilantro and beet for later. They are slower and less forgiving. Our list of the easiest microgreens for beginners ranks ten good options.
Step 2: Prepare the tray
- Fill the tray with 1 to 1.5 inches (2.5–4 cm) of growing medium. Deeper is not better: it stays wet and invites mold.
- Break up lumps and level the surface gently with your hand or a piece of card. A flat surface means even germination.
- Moisten it until it feels like a wrung-out sponge — damp all the way through, but no water pools when you press it.
Not sure which medium to pick? Compare soil, coco coir and hemp mats in our growing medium guide.
Step 3: Soak large seeds (skip this for small ones)
Large, hard seeds such as peas, sunflower and wheat germinate faster and more evenly after soaking in cool water for 8–12 hours. Small seeds such as radish, broccoli, kale and mustard do not need soaking, and some — basil, chia, mustard, arugula — turn into a slippery gel if soaked, which makes them impossible to spread.
See soak times by seed type for the full list.
Step 4: Sow densely and evenly
Microgreens are sown much more densely than garden seeds — the goal is a thick carpet, with seeds almost touching but not piled on top of each other.
| Crop | Seed per 10×20 tray (dry weight) |
|---|---|
| Radish | 25–35 g (about 1 oz) |
| Broccoli | 18–25 g |
| Pea shoots | 225–280 g (8–10 oz) |
| Sunflower | 170–225 g (6–8 oz) |
Sprinkle the seed evenly over the whole surface, then press it gently into contact with the medium with your palm. Do not bury small seeds. Mist the surface well.
Sowing too thickly is the most common beginner mistake. It traps moisture and causes mold and leggy, falling-over seedlings. If in doubt, use the lower number. Our seed density chart covers 14 crops.
Step 5: The blackout period (days 1–4)
Cover the tray to keep the seeds dark and humid while they germinate. You can flip a second tray upside down on top, or stack another tray directly on the seeds with a little weight in it.
- Small seeds (radish, broccoli, kale): a cover tray is enough.
- Large seeds (peas, sunflower): add 5–10 lb (2–4.5 kg) of weight on top. The seedlings push up against it, which builds sturdy stems and helps sunflower seedlings shed their hulls.
Check once a day. Mist if the surface looks dry. Most crops stay under cover for 3–4 days, until the seedlings are about an inch tall and lifting the cover. The blackout period guide explains how long each crop needs and why it works.
Step 6: Uncover and give them light (days 4–10)
When you remove the cover, the seedlings will be pale yellow. That is normal — they have not made chlorophyll yet. Within a day of light they turn green.
Give them 12–16 hours of light a day. A south-facing window works in summer, but in winter, or in a darker room, seedlings will stretch and flop towards the glass. An inexpensive LED shop light hung 4–8 inches above the tray solves this and gives straighter, greener microgreens. See how much light microgreens need.
Step 7: Water from below
Once the seedlings are uncovered, stop watering from the top. Wet leaves sitting close together invite mold. Instead:
- Pour about 2 cups (500 ml) of water into the solid tray underneath.
- Let the growing tray soak it up for 10–15 minutes.
- Pour off whatever is left so the roots are not sitting in water.
Most trays need watering once a day; check by lifting the tray — a light tray is a dry tray. The full method, with signs of over- and under-watering, is in how to water microgreens.
Step 8: Harvest
Most microgreens are ready when the first pair of leaves (the cotyledons) has fully opened, and before the second set — the “true leaves” — grows large. For many crops this is 7–14 days after sowing.
- Stop watering 12–24 hours before harvest so the leaves are dry.
- Hold a handful of stems and cut about ½ inch above the soil with sharp scissors.
- Eat immediately or store dry in a sealed container lined with paper towel in the fridge.
The roots and soil can go into compost. Most microgreens will not regrow — read why, and the exceptions. For storage times and washing tips, see how to harvest and store microgreens.
A day-by-day timeline for radish microgreens
| Day | What happens | What you do |
|---|---|---|
| 0 | Sow seed on moist medium | Mist, cover, place somewhere at 65–75°F (18–24°C) |
| 1–2 | Seeds crack open, white roots appear | Check and mist if dry |
| 3 | Seedlings ½–1 inch tall, pushing the cover | Uncover, place under light |
| 4–5 | Leaves turn green, stems straighten | Bottom water daily |
| 6–8 | Cotyledons fully open, 2–3 inches tall | Harvest when they look full |
| 9–12 | First true leaves appear | Harvest now — flavor gets stronger and texture tougher |
Common problems and quick fixes
| Problem | Most likely cause | Fix |
|---|---|---|
| White fuzz at the base of seedlings | Usually root hairs, sometimes mold | Tell them apart |
| Seedlings falling over | Too little light or water, or too dense | 8 causes and fixes |
| Yellow leaves after uncovering | Not enough light yet | Why microgreens turn yellow |
| Patchy germination | Old seed, uneven moisture, cold room | Germination checklist |
| Tiny black flies around trays | Fungus gnats in the medium | Get rid of fungus gnats |
How much does it cost?
A basic setup — two trays, a bag of coco coir or potting mix, a spray bottle and a few seed packets — usually costs less than a single month of buying clamshell packs of microgreens at a supermarket. The most expensive item is a light, and you only need it if you lack a bright window. Bulk seed is the biggest ongoing cost; pea and sunflower use a lot of seed per tray, while radish and broccoli use very little.
Frequently asked questions
Can I grow microgreens without a grow light?
Yes, on a bright windowsill, especially in spring and summer. Turn the tray every day so the seedlings do not lean, and expect slightly longer, softer stems than under a light.
Do I need to fertilize microgreens?
No. Seeds carry enough stored energy to reach harvest size in one to three weeks. Fertilizer is only worth considering for slow crops grown on bare hydroponic mats.
Are microgreens just sprouts?
No. Sprouts are germinated seeds eaten whole, root and all, after a few days in water. Microgreens grow in a medium with light, and only the stems and leaves are eaten. See microgreens vs sprouts vs baby greens.
Can I reuse the soil?
It is better not to reuse it straight away, because old roots can carry mold. Compost the used mat of roots and soil and start each tray with fresh medium.
What is the best temperature for microgreens?
Most crops germinate and grow well between 65 and 75°F (18–24°C), with indoor humidity around 40–60%. Much warmer and more humid conditions encourage mold.
Next steps
Once your first tray works, try a second crop with a different flavor, and stagger sowing every few days so you always have something ready. Our days-to-harvest chart helps you plan the timing, and the crop guides for pea shoots, sunflower and radish give step-by-step details for each.
