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Sink or float test for seeds?

Posted by californian 10 (My Page) on
Sat, Jan 30, 10 at 14:41

I read that when saving seeds like tomato seeds one should discard all the seeds that float after fermenting them.
I was wondering if the same test would apply to seeds out of a store bought package. If you drop them in a dish of water should you discard all the ones that don't sink as not being viable? And does this apply to all seeds. I notice none of my pepper seeds sink, but it could be because they appear to have a waxy coating on them. But I do know I put eight tomato seeds in water before I planted them and six sunk and two floated. After six days of waiting only six tomato seeds sprouted. Trouble is I mixed them up when planting them and don't remember which was which. None of the pepper seeds has come up yet, but pepper seeds usually take longer than tomato seeds to sprout anyway. Anyone else ever try the sink or float test and what did you observe as far a germination?

Follow-Up Postings:

RE: Sink or float test for seeds?

The seeds that you buy are already tested for viability. They are not gathered like you would do in a garden. They are fertilized in a protected greenhouse and after the seed is fertilized they tie a net bag around the flower after they pick off all the flower petals. The seed matures and drops into the bag.

They take test seed and grow it. They know just what the ratio of germination should be. In all my years of growing I have seldom had less germination than the seed company claimed.

RE: Sink or float test for seeds?

Some of the seeds I am using were packed for 2002, and who knows how old they were when they are packed.

RE: Sink or float test for seeds?

If they have 2002 on the seed package then that's when they were packed. That means they are 8 years old and if they were not stored right you might not get any.

The test for tomatoes is to cull the immature seed from the ripe seed. If you want to test these seeds without planting them, then you can sprout them in a wet paper towel, but if they sprout you will have to plant them.

RE: Sink or float test for seeds?

That's not a test I'd use with any confidence. Some seeds float simply because they are so light for their size. I recently started some callirhoe. These seeds came from my garden rather than a commercial package, so I was really concerned when they ALL floated when I poured the hot water over them. (They need a hot water soak prior to cold stratification). In fact, even though I knew the floater test isn't foolproof, I panicked and ordered some commercial callirhoe-- and then my personal seeds germinated upon removal from cold stratification. So, I guess I'm going to have lots an lots of callirhoe! The same is true for rose seeds, btw. Floaters germinate at a lower rate than the "sinkers," but many do still germinate, so I no longer bother to separate mine out.

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