In article , Dave Poole
wrote:

The two main reasons for soaking seeds a

1) To rinse out soluble enzymes within the seed coat which act as
germination inhibitors.

2) To soften the hard outer seed coat allowing moisture penetration
for faster germination.


Some have a waxy coating which must be removed before moisture
will penetrate. In nature this is presumably achieved by passing through
an animal's gut. Soaking with dilute detergent may be effective.

Norman Deno's "Theory and practice of seed germination" details
many experiments on different seeds.