Soaking Seed

[David Nicholson]

Is it fact, or a myth, when soaking seed prior to sowing that fertile seed sinks to the bottom and unfertile seed remains on the top?

[Lesley Cox]

Not necessarily. Light weight seed will float rregardless and very heavy seeds will drop even if not fertile. Better, in my opinion, to drop at least some, in the air. Frit seed for example, drop quickly and with a little sound, onto a sheet of paper while the infertile ones will drift down. Often size is an indication. In say Lewisias, the ones that are a bit smaller or a bit less black are not fertile. Usually. Unless you're cleaning them to send away, play safe and sow everything.

[David Pilling]

Hard to say because I always add a tiny amount of detergent which breaks the surface tension, so everything sinks.

That is another issue, very light seed will float but not because it is low density or contains air where there should be seed but because of surface tension.

Leave seed soaking long enough and everything sinks because it is water logged. Leave it even longer and it will all be dead.

Seems like a good rule that lighter seed is less likely to be viable, hence 'winnowing' blowing air over seed, and the dud light stuff blows away.

There also seems to be a group that believes in germinating amaryllid seeds by leaving them floating on water.

Finally, there are seeds which are designed to float to spread the plants - coconuts would be one example.

[Pascal B]

Is it fact, or a myth, when soaking seed prior to sowing that fertile seed sinks to the bottom and unfertile seed remains on the top?

With Arisaema a definite fact, infertile seeds will keep floating, even when using some detergent and soaked for 24 or 48 hours. Probably depends on which genus you are dealing with if it is fact or myth.

[David Nicholson]

Hard to say because I always add a tiny amount of detergent which breaks the surface tension, so everything sinks.

The seeds I'm soaking at the moment are various species of Iris and I too use a little bit of detergent added to the water.

[fermi de Sousa]

And I hope they all germinate for you
cheers
fermi

[Lesley Cox]

I wouldn't bother soaking irises except junos/oncos, and I'd rasp those a little as well.