Seeds are pelletized in order to create a uniform, round seed that is easy to mechanically sow.

Many ornamental flower seeds are commonly pelletized for precision sowing one seed per cell in a plug flat.

Photo of pelletized seeds of different colors.

Pelletized seeds are tumbled in a pan while inert powders like diatomaceous earth and binders form around the seed to provide a uniform shape.

Photo of untreated seeds compared to pelleted.

Photo showing a cross section of a pelleted seed with the seed and the surrounding pellet identified.

Pelleting adds 25 – 100% increase in size.

Encrusted pellets add <10% increase in size.

Photo showing a pile of encrusted pellets.

Photo comparing an untreated seed with an encrusted one.

Second photo comparing an untreated seed with an encrusted one.

There are two types of pellets distinguished by either "splitting" or "melting" when the coating is wetted.

Photo showing an example of melting coating.

Pelleted petunia seeds with a melting coating.

Photo showing an example of a splittting seed coating.

Example of a split-coat seed pellet.

The coating material is slowly added, while the seeds tumble in the pelleting machine.

This adds size and a uniform round shape to the seeds.

Photo of a pelleting machine.