Pre-soaking seeds - "The Float Test"

[Cormoran]

I keep reading that, if seeds don’t sink to the bottom of the cup during a 24-hour soak, they’re not viable. This is false. Some viable seeds will sink, some won’t; it’s not that easy to tell whether they’re viable without actually trying to start them. Don’t throw out your seeds just because they float!

I put this Cherry Dina seed from @bunny into a kelp/water/h2o2 mix ~24 hours ago. It’s been floating the whole time, and now it’s got a tail so it’s going into paper towels. Once it’s developed a bit further, I’ll take it from the paper towels and put it into my aero cloner to see whether the sprayers are too powerful for a seedling to survive. Hopefully it’ll grow up to be a big girl after that.

[Dirtron]

Not to burst your bubble but if you add H2O2 (like we both do) the O2 gas bubbles that evolve causes the seeds to float…

[Pigeonman]

Yeah I heard the same but when I toss my seeds into my scuffer and then into a cuppa-watta they float like Georgie in IT until the tails pop where they CONTINUE to float like Georgie from IT .

The ones that sank all seem to be the duds .

This is SANS H202 BTW.

[Cormoran]

I had 6 other seeds in the same solution, just a different cup - 1 of them sank, 5 floated. I’ve separated these 7 seeds into 3 lots to see what happens. Those other 6 are several years old and were stored in mediocre conditions, just stuck in a plastic case in a drawer, but they’re terrible genetics anyway so I’m using them for this experiment as well.

Also, I’m not seeing how this information “bursts my bubble” that the float test is inadequate and doesn’t necessarily give us any information. You seem to be agreeing with me, in fact… unless you’re saying that only seeds which sink in pure water will be viable, which @Pigeonman just addressed.

[Eagles009]

I don’t think float test is black and white proof of anything.

But I have found that seeds that float, then sink in 4-8 hours, then pop before 24 tend to lead to fast germination, good percentage, and vigorous plants

[Pigeonman]

I also must add that I refuse to soak longer than 24 hours out of paranoia. So if they don’t pop I still plant em and just keep an eye one them. SOME of them pop and grow, many that didn’t still DIDN’T.

Of those I’ve fished out of the bottom of a shotglass those (in my experience) all didn’t pop.

NOW, I DO NOT paper towel, so next time I get into a situation similar to above I WILL paper towel and see what happens.

[DougDawson]

Soaking seeds is just to soften the shells. Many times after 24 hrs the seeds are still floating and if I tap with finger most times they sink. In my opinion it means nothing in terms of viability.

[FiveGar]

I float to germinate. 1-3 days usually. 99% of seeds will float if you gently place them on surface of water and remain there if undisturbed. 99% will sink if you get them totally covered/submerge them. If you completely dry off their surface if you accidently sink one by placing it too hard in water they will often float again even after they’ve sunk.

Never seen any direct correlation between sinking and the seeds viability.

[Dirtron]

@Cormoran
I was making a pun, alluding to the fact that IMO it is the Oxygen bubbles from the H2O2 causing the seeds to float, as opposed to anything intrinsic to the seed, in this example viability…

[Mr.Sparkle]

I don’t actually want my seed to sink and prefer to keep them afloat which cold initial water and h202 helps.

As once they sink they dont have access to air i find seeds tend to stop or at least slow down growing, which a refloat with fresh water and a lightly dried off seed is all that required.

Mind you usually seeds are only in water for max maybe 2-3 days before they are planted.

[Herbie]

I soak mine till they sink. Not really working with old seeds here. I also just tap them after 24 hours to try to get them to sink. When a seed sinks I remove and plant it. I don’t want it to drown. I cover the cup of water so it won’t evaporate and cool the water.

A seed sinks, I plant it. They go in a dome and I try to keep the humidity up and temps near 80. Usually all up above ground within 3 days

For me about giving them sufficient moisture initially as much as testing.

[Cormoran]

Ah. I got the pun, I just thought you were saying the only reason the viable seeds weren’t sinking is because of the h2o2… though I did still have one seed sink in the h2o2 solution. Either way, we agree that it doesn’t necessarily seem to have anything to do with viability, I guess.

This experiment is actually my first time ever soaking a seed beforehand; I’ve almost always just put them straight into wet paper towels before this. A year ago I figured out that adding heat helped, which boosted my germination rates from ~60% to 90% or so… I don’t understand where this myth of seeds sinking indicating their viability came from, and it looks like it’s no longer commonly believed if it ever was, but I’ve run into a few old posts talking about it and figured maybe this should go into basic growing info, just in case we can save a few newer folk from throwing away perfectly good seed just because it floats.

[Pawsfodocaws]

I stopped dropping seeds in a cup of water early in my growing days. I learned it from the original og. It killed a bunch of my seeds. They all had a white fuzz around them. I’m sure I was doing it wrong somehow. But I’ll never do it again.

[Dirtron]

For me, since joining OG, space is always at a greater premium than seeds. So I always soak, then plant those that pop tap roots. I feel that the addition of H2O2 prevents the seeds from “drowning”. Just my preference.

[Tejas]

To go along with pre-soaking thought, if you find yourself, once you have planted in your medium of choice, that the shell is stuck firmly on the seedling try this. Cut a 2mm x 2mm piece of paper towel wet it with a drop of water and place that on top of the seed shell. That moisture will be enough to keep the shell damp enough to split on its own. I did this last night and this morning both seed coverings split enough for the cotyledons to push the shell off.

[G-paS]

Here are photos of seeds that didn’t sink.

[taiga]

I soak for 24 hours mainly to soften the shell a bit and then plant into soil, have never noticed a correlation between seeds that sink not popping or lacking vigour or vice versa.

[George]

I think it is as accurate as the “water judgement” for witches. They were tied up and thrown to the water, if they sunk, they were innocent but if they floated they were witches “rejected” by the water as they didn’t receive it with the baptism.

I just scarify them a bit (the seeds ) before throwing them to mild temperature water with some drops of peroxide so it helps moisture to come inside …

[Esrgood4u]

Or we could do it as nature intended and drop them in some dirt

[J-Icky]

How long were you soaking??? I always soak mine for 24hrs, then they go into barely damp paper towels til they pop open and then into a peat puck.

The only time I ever had issues with any kind of white fuzziness or seeds just turning to mush was when I was dealing with the original seeds that f ancestral skunk. The ones Sam said were like a 1 in 10 would actual pop. But I had 2 plates of 50 seeds each and I’m sure the sheer number of seeds that were mostly unviable to begin with is what allowed all the funky stuff to happen.