How to Test Microgreen Seed Germination at Home — The 5-Day Paper Towel Test

✍️ Sonia Pardasani, Founder BageechaBox | 🕐 4 min read | 🌱 Seed Guide

Quick answer: Place 20 seeds on a damp paper towel, fold it, keep it in a closed box in a warm spot, and count how many sprout after 3–5 days. Each sprouted seed is 5%. Around 85% or more is excellent for microgreens. Between 70% and 85%, sow a little thicker. Below 70%, the seed is too tired for a good tray.

In my workshops I teach this test on day one, because it saves so much frustration. Before you blame your watering, your cocopeat or your light, you need to know one thing: are the seeds themselves alive? A few seeds and a paper towel will tell you in less than a week.

When Should You Test?

• A packet has been open for months, or stored through a monsoon
• Your last tray came up patchy and you're not sure why
• You are about to sow a lot of trays at once for a business order
• You want to try seed from an unknown source

The Paper Towel Test, Step by Step

Step 1 — Count out 20 seeds

Take them from different parts of the packet, not just the top. Twenty makes the maths easy: every seed is 5%.

Step 2 — Soak if the variety needs it

Treat the test seeds exactly as you would for sowing. Peas, sunflower and methi get their normal soak first. Check our soaking guide if you are unsure.

Step 3 — Lay them on a damp paper towel

Wet a paper towel and squeeze it until it stops dripping. Space the seeds out, fold the towel over them, and place it in a small box or zip bag.

Step 4 — Keep it warm and dark

A kitchen shelf or cupboard works well — room temperature, away from direct sun and AC vents. Check once a day and re-dampen the towel if it dries.

Step 5 — Count the sprouts

Count seeds showing a clear white root. Fast varieties like mustard, radish and moong usually show within 1–3 days. Larger or slower seeds like sunflower, beetroot and coriander can take 4–7 days.

Reading Your Result

Seeds sprouted (of 20)	Germination	What to do
17–20	85–100%	Excellent — sow at normal density
14–16	70–80%	Usable — sow 10–20% thicker
10–13	50–65%	Patchy trays likely — use for a garden bed instead
Below 10	Under 50%	Replace the seed

Why Low Germination Hurts More in Microgreens

In a garden, a few failed seeds don't matter. In a microgreen tray, seeds are sown shoulder to shoulder. Dead seeds sit in warm, damp cocopeat and are often the first place fungus starts. That is why tired seed causes two problems at once: a thin tray and a mould risk.

Good Result, Poor Tray?

If your seeds pass the paper towel test but your tray still comes up patchy, the problem is in the growing conditions — usually uneven sowing, dry patches in the cocopeat, or too much heat. Our germination troubleshooting guide walks through each cause.

Frequently Asked Questions

Q: How do I check if my microgreen seeds are still good?

Do a paper towel test: 20 seeds on a damp towel in a closed box, counted after 3–5 days. Each sprouted seed is 5% germination.

Q: What is a good germination rate for microgreens?

85% or more is excellent. 70–80% is usable if you sow a little thicker. Below that, trays tend to come up patchy.

Q: Can I sow the test seeds afterwards?

Yes — gently place the sprouted seeds on moist cocopeat. They are fine to grow on, though they may lag a day behind the rest of a new tray.

Q: Why do some seeds take longer in the test?

Seed size and variety. Mustard, radish and moong sprout in 1–3 days; sunflower, beetroot and coriander can take up to a week. Cool rooms slow everything down.