Damaged seeds seem to float on the water, because they are actually empty and lack the nutrients and other materials need to propogate into the plants.

Why do dead seeds float?

Some people think that if seeds are thrown into water the good ones will sink and the dead seeds will float, but this notion is not sup- ported by facts. When seeds float it is often because an air bubble has become attached to them or because they have not become wet all over the surface.

Are seeds bad if they float?

How do you know if your seeds are still viable? Simple, do a seed germination test. Place the seeds in some water. The ones that sink are still viable – the ones that float are dead.