Choose a crop and your tray size to see how much seed to sow. The calculator scales tested seeding rates for a standard 10 × 20 inch tray to any size, including custom trays measured in inches or centimeters.
| Crop | Seed per 10×20 tray | Soak | Days to harvest | Note |
|---|---|---|---|---|
| Radish | 25–35 g (0.9–1.2 oz) | Not needed | 7–12 | Fast, forgiving, peppery. |
| Broccoli | 18–25 g (0.6–0.9 oz) | Not needed | 8–12 | Mild; harvest before true leaves. |
| Kale | 15–22 g (0.5–0.8 oz) | Not needed | 8–12 | Mild and sweet. |
| Red cabbage | 18–25 g (0.6–0.9 oz) | Not needed | 8–14 | Purple stems; easy. |
| Kohlrabi | 18–25 g (0.6–0.9 oz) | Not needed | 8–12 | Purple stems, mild. |
| Mustard | 15–20 g (0.5–0.7 oz) | Do not soak | 8–12 | Seeds turn gel-like when wet. |
| Arugula | 10–15 g (0.4–0.5 oz) | Do not soak | 8–12 | Sow evenly; seeds clump when wet. |
| Amaranth | 8–12 g (0.3–0.4 oz) | Not needed | 10–14 | Tiny seeds; keep surface moist. |
| Basil | 7–10 g (0.2–0.4 oz) | Do not soak | 16–25 | Slow; sow dry on damp medium. |
| Cilantro (split seed) | 30–40 g (1.1–1.4 oz) | 4–8 hours (optional) | 16–21 | Slow, uneven germination. |
| Beet | 30–40 g (1.1–1.4 oz) | 4–12 hours (optional) | 12–18 | Seed caps cling; mist often. |
| Pea shoots | 225–280 g (7.9–9.9 oz) | 8–12 hours | 10–14 | Can give a second, smaller cut. |
| Sunflower (black oil) | 170–225 g (6.0–7.9 oz) | 8–12 hours | 8–12 | Use weight in blackout to drop hulls. |
| Wheatgrass | 250–340 g (8.8–12.0 oz) | 8–12 hours | 7–10 | Hard red wheat berries. |
How to use the result
- Start at the low end of the range for your first tray. Over-sowing causes more problems than under-sowing.
- Weigh dry seed, before any soaking.
- If your seed is older or germinates poorly, you may need a little more — our seed density guide explains how to adjust for germination rate.
- For soak times and why some seeds must never be soaked, see soaking microgreen seeds.
Where these numbers come from
The rates are typical starting points drawn from published microgreen seeding guidelines and common practice. Seed size varies between varieties and seed lots, so treat the ranges as a starting point and adjust after your first tray.