Normally seeds would not stratify in the freezer. Freezing may help some species to germinate but not through stratification.Your question would be easier to answer if you mentioned what species you are wanting to grow.
I was thinking of plum in particular, but fruit and nut trees in general.
I thought stratification was a period of cold, that naturally occurs in winter but can be noticed via the refrigerator.
Since winter includes freezing cold I thought a freezer might do.
Stratification which is one way that normally wakes up seeds, usually it involves enzymatic or at least chemical action. Thus, stratification requires liquid water. Freezing temperatures do other things, like physically breaking a membrane that prevents the seed to take up = imbibe water, depending on the type of seed. Freeze tolerant seed "waits" until relatively warmer temperatures to begin or sometimes finish stratification. That said there can be more complicated multistep processes that are required for some species. More is found in the above links. Most germination protocols for perennials, difficult annuals, and some trees will be found in Deno for free download, and most of the species of trees, shrubs, and perennials considered in temperate permacultural applications are extremely well covered even in the older = inexpensive copies of Hartman and Kester.
The most general thing that can be said is that freezing does not stratify.
Thank you for your detailed reply.
I think I would fail at trying to follow a precise protocol .
Instead I' guess I'll secure the seeds in a protected place outside and let nature take its course.
I'm thinking sand or potting soil in a sub irrigated planter.
i stratify seeds in the fridge in winter in moistened folded up paper towel in little plastic baggies. works good, and i think it's safer than sticking them outside somewhere. Once they've imbibed water in the stratificaton process, i don't think you'd want to let them freeze.
SOME seeds can be put in the freezer, some even i find like it /are at least ok with it. with others, you run the risk of ruining the seed ( i think most nuts are too sensitive to make it ok).
a simple way to think about it is anything that is cold tolerant to zone 3-4 will probably be ok in the freezer. i disagree with the above saying freezing is not stratification, stratification can be accomplished by using the freezing, but again only for SOME seeds of very cold tolerant species. roses in particular, very tolerant of cold and quite tricky to start, i have experimented with using the freezer with good results.
all that said (and also adding here this is my opinion based on my experiences, so YMMV) my understanding is that if you are going to freeze seed, it is best to freeze dry seeds, this being the more questionable iffy ones, they should be dry before freezing. thats not stratification which should be cold and wet/damp really. the advantages to putting dry seeds in the freezer is that you can kill bugs, theres some seed eating bugs that can wreck a whole seed harvest, so 2-4 days in the freezer - DRY- can kill the bugs too. length of time matters. freezing seeds briefly for a days is different than freezing the seeds for months on end.
i suppose the way i think about it is that the benefits of stratification mainly come from the thaw cycle...so idk if the freezing is actually a good way to stratify, technically as i said above, but thawing. its the freeze/thaw cycle that does the trick, of swelling the seeds, breaking down the shells or other inhbitors, and breaking dormancy.... and making them ready to pop once it's warm enough.
but i have experimented with it - i find its ok for SOME things ...mainly trees. most of the time this is because i find it easy to harvest things and put direct into the freezer fresh, cherries and berries and plums are what i have tried. in this way i had a lot of success starting seeds that had been frozen right in the fruit...not stored as seeds...but just coincidentally because that was the easiest to preserve them for later. the cherry seeds i did this with i got more that way then cleaning them, partially drying them and doing the stratification the proper way either outside or in fridge. so yeah my own experiences says it is ok for plum, cherry and roses...i have probably tried it with more than that but thats all i can think of right now.
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