Cold Stratification of Seeds.... Fridge or Outside?

JoeR

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As many of my threads have indicated, I am starting tons of Seeds this winter. Hopefully as you know, all seeds can benefit from cold stratification. Not necessary for some but germination rates do increase.


So I have been reading M. Dirr's propagation manual (absolute MUST have for your book collection) and he says you can either fall sow or C.S. them in the refrigerator and that got me wondering....


What would be better; sowing them in soil now and placing them outside OR should I C.S. them in the fridge?



Natural v. Artificial?



I think outside would make more sense because a) it's natural and b) more airflow/ less fungal issues. Most recommend keeping them in a plastic bag with some sort of media in the fridge but that just sounds like a recipe for rot and mold.




What do you think? What have you read? Discus.
 
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Just make sure animals don't eat it. I did beech last year, in a pond basket, in potting soil and buried in the ground. Good germination. Don't know with other species. Did the paper towel trick in the fridge, good germination. Some fungus, i replaced the paper every month. The papers with more mold did not have less survivors.
 

mwar15

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I have always used a paper towel or peat moss and every few weeks I rotated them around. I also leave the ziplock open for a day here and there to get some fresh air.
 

M. Frary

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The only seeds I've ever planted were elm. I took them off of the tree this spring and planted them the next day. It looks like 90% grew. The only cold stratification they saw was maybe a cool breeze coming in the window of the car.
 

JoeR

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Just make sure animals don't eat it. I did beech last year, in a pond basket, in potting soil and buried in the ground. Good germination. Don't know with other species. Did the paper towel trick in the fridge, good germination. Some fungus, i replaced the paper every month. The papers with more mold did not have less survivors.
I didn't think about animals, good to know



So it appears the fridge is the better option as long as you replace the media.
 

Cypress187

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Why would you risk natural stratification (with all the variables) if you can put them safe in ur fridge.
 

coh

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I haven't worked with seeds much, but a couple of years ago I experimented with Japanese maple, dawn redwood, and european hornbeam. Treated all the same - soaked in warm water for some period of time (can't recall, followed directions on line), then placed in baggies with damp sphagnum moss and into the refrigerator. Got very good sprouting on the JM (something like 27 out of 35 seeds), decent sprouting on the dawn redwood and hornbeam. Eventually some mold developed in the baggies, but that was after most of the seeds had sprouted.

I opened the baggies to aerate and check for sprouting about once a week.

Small sample size, but this process worked very well. Outside up here, the seeds would have been frozen for much of the winter. Figured a more controlled environment might work better.

Note, I was surprised how quickly the JM seeds started sprouting...think some were going within about 3 weeks.
 

0soyoung

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Why would you risk natural stratification (with all the variables) if you can put them safe in ur fridge.
Which is the entire point of 'stratification' (the process of treating stored or collected seed prior to sowing to simulate natural winter conditions that a seed must endure before germination) - higher germination rates.
 

Leo in N E Illinois

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I once tried to fall sow chestnuts. Did not think about animals. It didn't work because very quickly the squirrels found them and ate all but a couple. The couple that came up in spring I lost all but one because even in spring the remaining cotyledon (seed halves) were still deemed tasty by the squirrels. The lone survivor the cotyledons ripped off without uprooting the seedling, so the seedling survived. By the way, I don't think chestnuts have much of a future as bonsai, many of the same issues as one has with beech, only more so. Big leaves, etc.

Following year did ginkgo seed. This time covered the flat outside with 1/4 inch hardware cloth. I wired the cloth down on all 4 sides so it couldn't be lifted by the varmints. Left the cloth on through the growing season, removed it the following fall after leaf drop. Trees came up through the cloth, most did not branch the first year, so it was easy to just lift the cloth off after leaves fell in autumn. Had about 80% of the 20+ seeds survive the one year mark.

Now I usually put bigger edible seeds in refrigerator for cold stratification. Tiny seeds, ones that are not obvious rodent or bird food are fine for autumn sowing outside.

By the way, ginkgo seeds are very edible, once washed free of the noxious flesh of the outer seed coating. Boiled or roasted they soften up and are delightful, with a very nice mild flavor. Toss a few in a beef or chicken broth, let them cook, then serve. Yum.
 

sorce

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Coffee filters work better than paper towel.

Sorce
 
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stays wet longer, so be sure not to make it to wet. Roots penetrate it faster i have the impression.
 

0soyoung

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Put your seeds on a little rectangle of plastic and fold it once to cover them. Put this little packet on a rectangle of damp paper towel (or coffee filter of you prefer) and fold it over the plastic. Sprouts don't get stuck in anything - easy peasy, simple pimple, no problem :D.
 

BunjaeKorea

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Lol, I just put my seeds in an envelope and leave them in a cold place like unheated back room in winter.....they always have a high sprout rate...I guess I am just lazy eh? Then if you plant them end of winter they sprout just fine in my case anyway
 

f1pt4

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I have some european hornbeam seeds I would like to stratify. It says they need warm stratification as well as cold stratification.

Has anyone used Sphagnum to stratify?

Can I do warm stratification and cold stratification of the seeds in the same medium without having to change it?

The packet states 30-60 days warm, 60-120 cold.

Thanks in advance. Never done this before.

I guess you can say I'm a sowing seed virgin. (waiting for Sorce to chime in with a Haiku)
 
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did it with carpins koreana last year, good results with paper towel.
 

garywood

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Mixing hydrogen peroxide @ 10% in the towel dampening water will really help with the mold.
 

Bonsai Nut

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I didn't think about animals, good to know
One year I germinated a bunch of Japanese maple seeds. The birds went NUTS. They pulled the seedlings out of the ground and ate any portions of the seeds remaining.
 

f1pt4

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Mixing hydrogen peroxide @ 10% in the towel dampening water will really help with the mold.
So it's now like day 4 of warm stratification of the Japanese Hornbeam and European Hornbeam seeds

Since no one chimed in on using Sphagnum as a medium for the stratification process, and everyone touted the benefits of good ol paper towel, that's the route I done did take. With 10% hydrogen peroxide.

I took a peak inside the moist towelettes and I noticed that although the Japanese Hornbeam seeds seem unaffected, the European Hornbeam seeds, about 50% of which are showing signs of mold.

What now? Remove the moldy seeds? put em in a seperate bag? spray them down with bleach and do a dance for the gods?

Yes I know the stratification is started a little late. Yes I know I should read a book on starting seeds. All that aside, any ideas how to proceed forward? There's still about 4 months left in the stratification process.

Thanks in advance.
 

coppice

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Most of what I am growing from seed for trees, will likely never see a day on a tray as bonsai. Back when I had a cold frame, seeds went into a pot with mostly bonsai soil (enriched with some peat), Into the cold frame to slumber there till spring.

Now-a-days without a cold frame, seeds nuts etc sit in tupperware with just barely damp peat in the fridge till about the third week of February and are then handled as though they were winter sown, except I use a taller tote instead of milk jugs.
 

JoeR

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Is mold on the actual seed an issue?


They slipped my mind and I hadnt opened them in a while, so I did so today. Towel was quite moldy, and I noticed some of the seeds themselves have mold on them.

I am going to replace the towel tomorrow with coffee filters.
 

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