How Much Microgreen Seed per Tray
Seed weight per 10 x 20 tray for radish, pea shoots, sunflower, broccoli, kale, arugula, and more, plus how to scale for smaller trays and how much to buy.
Published by ThriveThyme
microgreens seeding rate pea shoots sunflower indoor gardening
Some outbound seed-house links may be affiliate links.
How Much Microgreen Seed per Tray
Microgreens are sown far thicker than garden seed. Weigh seed rather than counting it. A kitchen scale that reads in grams is the most useful tool you can buy for this.
The Microgreens Desk does this math for your tray size, number of trays, and sowing schedule.
Starting Rates for One 10 x 20 Tray
These rates come from Utah State University Extension trials where listed, and from Penn State Extension guidance of about 10 to 15 grams for small seed.
- Arugula: 10 g, no soak
- Cress: 10 g, no soak
- Mustard (mizuna): 15 g, no soak
- Broccoli: 28 g, no soak
- Kale: 28 g, no soak
- Red cabbage: 28 g, no soak
- Cilantro (split seed): 28 g, no soak
- Beet: 30 g, soak 4 to 8 hours
- Swiss chard: 30 g, soak 4 to 8 hours
- Radish: 42 g, no soak
- Sunflower (black oil): 48 g, soak about 12 hours
- Pea shoots: 150 g, soak about 6 hours
Treat these as a first try. Fresh, high-germination seed can go a little lighter. Old seed needs more. If you are not sure, run a quick check on the Seed Viability Check desk.
Smaller Trays
Scale by surface area.
- 10 x 10 tray: about half the 10 x 20 rate
- 5 x 7 clamshell or dish: about one sixth
- 5 x 5 tray: about one eighth
Penn State also notes that one tablespoon of brassica seed weighs about 11 to 12 grams, which helps if you measure by volume.
Too Thick or Too Thin
- Too thick: seedlings crowd, air cannot move, and mold risk climbs. Cut the rate by a quarter next time.
- Too thin: bare patches and a light harvest. Raise the rate a little.
How Much Seed to Buy
One 10 x 20 tray of pea shoots uses about 150 grams, which is more than 5 ounces. A weekly tray for a month is about 600 grams. Seed packets hold far less than that, so buy microgreen or sprouting seed by the ounce or in bulk. Mississippi State University Extension makes the same point.
Plan the whole season on the Microgreens Desk before you order.