That’s why I am testing the float test with each cross where I think that it could save me time and space. I would never assume that the results of the test for one cross would apply to any other cross and I would never throw out a seed based on the float test unless I had verified the float test for the cross. If I ever do find a cross that produces many seeds but few germinations where the float test is reliable, I will use the float test.
For example, one of the crosses I tested this year was Lyda Rose X Mutabilis. In general, crosses done with Mutabilis pollen have low germination rates. Of the 245 seeds I got from this cross, only 31 sank. If the float test is valid for this cross, I would only have had to plant 31 seeds instead of 245, which is a significant savings in time and space. Of course, since I don’t know yet whether the float test is valid for this cross, I planted all 245 seeds, keeping the floaters separate from the sinkers so that I can compare germination rates.
With a little practice, the float test can be done quite quickly. The amount of time it takes to test 300 seeds is about the same as the time to test 30 seeds. The float test is a waste of time if you only have a few seeds from a cross, regardless of whether it is reliable.