The float test to determine seed viability is not reliable. To perform the float test, you put seeds in a cup of water to see if they sink or float. The idea is, if they have enough mass to sink, they should be viable. If they float, they’re dead. The problem is, with all the zillions of different seed shapes, sizes, weights, and textures, this test is not reliable. Some seeds are always going to float and others are going to sink regardless of their viability. Think of carrot seeds. They are tiny and have so little mass, even the freshest seeds will float—immediately failing the test—even when they are viable. So, despite all the recommendations, don’t waste your time with this test.