The seeds of many agricultural species are either small
or irregularly shaped, making it difficult to singulate
them for planting.
New types of planters, particularly
vacuum plate planters, have largely overcome this
problem. However, even if the seeds can be dropped
individually to control spacing, it is difficult with
small seeds to control the depth of planting.
pelleting addresses both of these problems by coating
seeds with clay or other materials to give them a
uniform shape and size and increasing their size and
density to allow more precise placement in the soil.
Pelleting is used most widely for small field-planted
seeds such as lettuce and alfalfa, but small and
valuable seeds, such as petunias or geraniums, are often
pelleted to increase their size and facilitate their use
in automatic planters in greenhouses.
Modern types of
pellets split upon imbibition – when they absorb fluid
and swell - freeing the seed from any impediment by the