Biochar in Seed-Starting Mixes

A modest rate

Seedlings are more sensitive to abrupt changes than established plants. Biochar in seed-starting mix is helpful — at a low rate. 5–8 % is plenty.

Prep

• Screen / sift. Pick coarser fragments out of the biochar with a 3 mm mesh. You want the fine particles only in contact with new roots.
• Charge gently. Soak in diluted compost tea (1:10) overnight. Let drain before mixing.

Blend

• 5–8 % of the starter mix by volume.
• Avoid peat-heavy mixes that are already very moisture retentive — biochar compounds the retention and can over-wet seedlings. Use a peat-light or peat-free base.

What to expect

• Faster even-drying across the flat
• Less rebound compaction as seedlings transpire

Coverage

One 6.5 L bag covers roughly 13 standard 10 L flats at a 5 % blend. Our biochar ships as a coarse chip, so sieve or crush the fraction you want for seedling mix — a finer particle sits better in a plug tray.