Scott wrote:

Hi All,

Can anyone explain the reason that seeds would be coated with clay? I
realize that it makes the seeds bigger and easier to handle, but what
effect does it have on the seed germination, etc.


The clay coating (pelleting) is primarily to make them bigger and easier
to handle. For example, I plant lettuce in 200 trays (200 cells per
flat) and I want only 1 plant in each cell. With normal lettuce seed
it's a real chore to handle only 1 seed. With the pelleted seed it's a
snap.

The process of pelleting seeds sometimes also involves "priming" the
seed. I'm not sure whether this is intentional or not, or actually how
it is done, but the effect is to pre-germinate the seed. This stresses
the seed somewhat, limiting its storage life, but it makes a batch of
seed germinate more uniformly. In the case of lettuce, there may be a
couple of days difference in the germination time of raw seed, but for
the primed seed it's maybe half a day. This helps people who are
planting large quantities of seed on a schedule manage the plantings
better.