Seed Pelleting & Filler, Binder & Pellet Weight

Seed pelleting coats tiny or irregularly shaped seeds — carrot, onion, lettuce, tobacco — in a filler held together by a binder, building them up into uniform, round, free-flowing pellets. The added size and regular shape let the seed singulate cleanly in precision planters, so each cell drops exactly one seed at the right spacing.

From your seed weight and the pelleting ratios, the tool gives the filler weight, the binder weight, and the finished pelleted-seed weight (seed plus filler plus binder). For example a small batch of seed coated to several times its weight in filler with a small fraction of binder yields the total pelleted weight you'll actually sow.

Filler is the inert bulking material that builds the pellet's size and shape — commonly clays such as kaolin or bentonite, calcium carbonate, talc or diatomaceous earth. It carries the seed up to a sowable size and, ideally, splits open readily when wet so it doesn't restrict germination.

The binder is the adhesive that glues filler to the seed and to itself so the pellet holds together and stays free-flowing — typically a water-soluble gum or polymer applied in small amounts. Too little and the pellet crumbles; too much and it can harden and delay imbibition, so the ratio matters.

Small, light, angular or hairy seeds that are hard to sow precisely — carrot, onion, lettuce, tobacco, celery, many flowers — gain the most. Pelleting turns them into uniform spheres a planter can singulate, cutting seed waste and thinning labour. Large, already round seeds rarely need it.

Pelleting builds the seed up into a large, round, opaque pellet that hides the seed's shape, maximising size and flowability. Encrusting (or coating) adds a thinner layer that increases weight and smooths the surface but keeps the seed's general shape. Pelleting uses more filler; encrusting uses less.

Vacuum and mechanical precision planters pick up one seed per cell by size and shape. Tiny raw seeds slip, double or skip, ruining the stand. Uniform pellets singulate reliably, so you get even spacing, predictable plant population and far less thinning — which is the whole point of precision sowing.

A well-made pellet should split or soften with moisture and not hinder emergence, but a hard or thick pellet can delay imbibition or block oxygen, especially in dry or crusting soils. Keep the binder modest, ensure good seed-to-soil moisture, and test germination on a sample before sowing the whole batch.

They're solid planning quantities from your seed weight and ratios. Real coatings vary with the build-up process, filler density, moisture and the pelleting equipment. Treat the result as a recipe starting point, weigh a trial batch, and adjust the ratios to get the pellet size and flow your planter needs.