S Brand Sprout Mix – Enriched Worm Castings

Enriched worm castings for seed starting

Give your seedlings a stronger start with Elmer’s Gold worm castings enriched with kelp, humic substances, minerals, and microbial inoculants. Blend S Brand into your seed-starting medium before planting.

How to use

Mix 1 scoop of S Brand with 3 scoops of seed-starting medium. Use the same scoop for both ingredients. This makes a 25% blend by volume—the proportion used in our trial.

Mix thoroughly, then plant according to your seed supplier’s instructions. Keep the growing medium moist but not waterlogged. S Brand is an amendment, not a standalone potting mix.

Choose your size

• 4 lb — $20: Makes about 4 gallons of finished seed-starting blend.
• 16 lb — $60: Makes about 16 gallons of finished seed-starting blend. Four times the product for three times the price.

Finished volumes assume the 1:3 blend above and our specification estimate of 4.10 lb per gallon. Moisture and settling affect volume, so use scoops when mixing. Packages are sold by net weight; shipping is calculated at checkout.

See our day-46 tomato comparison

We grew red cherry tomatoes using three approaches: store-bought seed-starting mix with tap water; 75% starting mix plus 25% Elmer’s Gold with reverse-osmosis water; and 75% starting mix plus 25% S Brand with reverse-osmosis water.

This was our practical growing comparison. Because the control received a different water source, it does not separate the effect of the amendments from the effect of water. Your results will vary with seeds, growing medium, and care.

Watch the growing trial for the full comparison.

What makes S Brand different?

We start with Elmer’s Gold worm castings and blend in amendments that contribute kelp, humic substances, calcium, trace minerals, and microbial inoculants. You get the ingredients combined in one prepared blend, without purchasing and measuring several separate products.

Storage

Keep in a cool, shaded location away from extreme heat and direct sunlight.

Questions about your growing setup? Ask Adam.

Download the one-page growing guide (PDF).

Explore our castings reports and growing trials. The laboratory reports cover the base castings, not the finished S Brand blend.