You have soaked your seeds and you see they are floating. People say if seeds float they are dead / unviable? True or false?
There is a lot of misunderstanding around the floating seed rule. In short, this rule ONLY applies to fresh seeds and NOT dried seeds. For a more detailed rationale, please continue reading :)
Some seed vendors wash their seeds in water straight after harvesting and before drying. This is when the seeds are still fresh and moist and not dried. It has been our experience that with freshly harvested seeds as a general observation, unviable seeds float and viable seeds sink. When we say unviable, we mean seeds that are underdeveloped or deformed in one way or another. Underdeveloped seeds are a natural ocurrence especially early season and late season when some seeds inside the pods have not had enough time to fully mature and usually are small and translucent, as their embryo's have not fully developed.
These seed vendors use this technique as a very rough way to eliminate most of the potentially unviable seeds. Floating seeds are simply skimmed off the water's surface and discarded and seeds that have sunk go on to be dried and sorted. This method is not scientific in any way or form.
So the misunderstanding lies in the fact, that while this principal is true for fresh seeds, this rule does not hold true for dried seeds. And here is our rationale:
Dried seeds have very hard seed coats. These seed coats are usually coated in oil. The purpose of the seed coat is to protect its contents and prevent the seed from germinating until the conditions are right to do so. And this means the seed coat has to hermetically seal the embryo for a number of years if need be. Like a time capsule.
So here is the crux. You have a seed that has a relatively hard impermeable outer coat that is covered in oil. Water uptake is not always immediate. Ontop of this some seed are very flat and have a large surface area that makes them ideal for floating. Add to this the fact that most seeds vary between 0.007 and 0.01g in weight. Hardly enough to break the surface tension of water. I think one has to agree that seeds have everything going for them to float - given these factors, it is no surprise that seeds float!
There is an exception to the rule and while every variety/species of chilli has a different shape of seed, annuums do tend to have seeds that are more oval and are denser (and heavier). Annuums do tend to sink more easily than the other varietals.
With a little warm water and a little coercing, most dried seeds do sink eventually. Seeds will start to sink once the oils have loosened from the outer seed coat and the seed starts absorbing water/moisture and starts getting heavier.
So in short, the floating seed rule ONLY applies to fresh seeds and NOT dried seeds. So if your seeds are floating, it is perfectly normal.
If your seeds are floating they have not yet started the process of absorbing water and they will not swell untill they do so. This may be due to oils that are coating the seed outer coat, making the seeds impermeable.
Add a little dishwashing liquid to the water. Dishwashing liquid soap will help degrease the seeds and lift oils from the outer layer of the seed - allowing your seed to absorbe water better. Once you have added the dishwashing soap, gently rub the seeds between your fingers to expedite this process.
You should be using a heating pad when germinating your seeds. Warm water at around 25 - 30C will help dissolve any oils easier and will soften the seed coat easier.
You can also look out for our specially formulated Pre-soak liquid. It is specially formulated to help with the lifting of any oils, disinfecting seeds from any potential bacteria or fungus and also will help soften the outer seed coat. This will speed up the germination time substancially.