Seed stratification experiment

I've had some success direct sowing fruit seeds, and massive failure stratifying seeds in the fridge, but this winter I'm going to set up an experiment testing several seed stratification methods including comparing peat moss and sphagnum moss at 3 temperatures : unheated porch varies from near freezing to semi room temp, likely 32-45 degrees all winter, an unheated basement which does get cool but also has more consistent temperatures, outside frozen in a rodent proof container, with all the lovely temps a Minnesota winter offers. I can't direct sow since we're already under a foot of snow and temps outside in the teens, I wish i could.

My hypothesis is that the sphagnum moss will be better for air flow and reducing mold, and that the basement's more moderate temp swings will help keep the seeds dormant until they are really ready to go. I'll be trying several fruit and nut types, those that I have large numbers for I'll do a full experiment, those with less numbers will just get the sphagnum basement treatment.
Thoughts? Suggestions?

Update

I've gotten all my seeds packed up into their peat/spagnum and put into several different stratification climates.

Most have not changed in any way obviously after 2 weeks, except:

Hickory nuts in the spagnum have some mold/mildew on the surface of the nuts, not on the finer peat bag though.
I had a Chinese Quince seed germinate after a week, not ideal right now since I'm looking at at least 4 more months of frozen ground and another 1.5 of frost/freeze potential. I'll pot it up and see how the rest do.

I did not have a lot of luck with cold stratifying. I think what is needed are cold temperatures and swings in temperatures to break dormancy. The fridge does not do that and it is maybe too warm either. I had success with quince though. There is a method with coffee filters which worked a bit better for me. I tried starting seeds outside, but i does not get cold enough here or maybe I wasn' t watering them sufficiently.

I'm thinking it requires temperature swings too now, which my porch seeds will experience, while the basement one will stay more stable. The seeds I left outside should have temp swings too. The porch has already gone from 37 F to 56 F depending on outside temp.
I needed to get a methodology for my own, I'll report back whatever failure and successes I have.

I stratify all my seeds outside mixed with compost and buried in the ground in buckets. No mold, no early break of dormancy. It works very well for the 40+ species I've grown here in the northeast.

So much depends on your local climate. Here in central NJ I have witnessed winterkill on many occasions when the rather predictable late January- early february warm spell hits. Plants respond to the false spring, stick their little heads up out of the ground and start to reach for the sun, and Jack Frost jumps up and down on them with hobnail boots until they are very dead.

In my location, I would never rely on outdoor stratification, due to the consistency of this false spring.

Interesting, it seems like a really deep mulch would moderate any early warming effect, but as long as it works for you, that's all that matters.

Akiva Silver wrote:Interesting, it seems like a really deep mulch would moderate any early warming effect, but as long as it works for you, that's all that matters.

And a very deep mulch might work. I think that part of what happens in this sort of thing is that we may be trying to grow plants outside their natural ranges. In a place where it gets cold and stays cold until it gets warmand stays warm, the whole cold dormancy germinate when it warms thing works great. Nature has been doing it with success for ages . But that same plant, in a place that fluctuates the way our winters do here, might fail miserably. Not the right adaptation for the environment.

Which takes us to another one of those things to consider with the plants we choose. How do their native environments compare to the one we want to grow them in? And what accommodations should we make for differences?

Russel, thank you for doing this thread.
I have tried stratification of many different seeds, both trees and flowers. Some of the flowers have worked well as long as I controlled mold. The trees seem to be much harder though. I have not been successful with any inside using both the fridge and freezer. I have tried just the fridge and a combination of the two, freezing them for different amounts of time before moving them to the fridge.

I have only truly been successful outside with Lindenwood, maple, and Butternut. No success with fruit trees yet.

Akiva, can you tell us what kind of compost you have used outside?

Look up Norman C. Deno. He wrote a massive book on seed stratification, covering thousands of varieties, which is free online. It details the results of thousands of experiments, and lists simple methods to achieve success. He found that fluctuating temperatures have nothing to do with it, in most cases; seeds have chemical time clocks which run fastest at certain ideal temperatures, usually 40 or 60 degrees.

Seeds are mostly good.
A few observations:
Akebia seeds all molded but three. I planted those out just to see if they'd be ready but no luck so far.
All others seem good, I had some freezing which was disappointing I'm worried about the chestnuts and paw paw for sure. I hope to set up a cold frame capable of allowing for a long taproot on the nut trees, I'm thinking of a big Tupperware with drainage holes set against a south wall with a plastic roof glazing top.
The ground simply won't be thawed here in time to plant these nuts and fruits if they start sprouting in February or March.
No other mold issues, no sprouting of anything yet either but perhaps this week since we've warmed up a bit and the porch will be in the low 40's up from low 30's.
I'm gonna check out that Deno guy's work. I was hoping to find some sort of expert's website before starting all this with little luck.
More updates as the winter drags on.
Have a good one!

Here's the link to Deno's Second Edition, and his latest supplement here.

Update: First seeds sprouted.

I read up on the work of Norman C. Deno. Unreal, must read for anyone looking to start things from seed.
After comparing my seed list to his and his conditions I took my ginko biloba seeds out of stratification and placed them in a 70 degree area near my furnace, within 3 days I have 4 of 6 swelling and sprouting.
Other seeds look good so far, no major mold issues.
I've also scored cold frame materials. Home Depot had a clearance of last year's clear plastic storage bins with good snap lids. 2$ each for big ones. I got 10 and plan on doubling them up into a sealed greenhouse type coldframe. I'll post some photos friday when I have my day off and can get them set up.

Since I need to get the ginko tree growing soon I'll be starting several non stratified seeds in the cold frames including black locust, honey locust, kentucky coffee tree, japanese raisin tree, and yellowhorn.

I love vermiculite as medium for stratification in the fridge our outside in pots. When time for planting, seeds are easily picked out and sown into proper medium. I've been stratifying seeds of Taxus baccata taht need two years of cold and warm alternations, all seeds look healthy and they will be sown in spring. I stratified with success in vermiculite seeds of apple, pawpaw, pear, hawthorn, nanking cherry...

I've had plenty of luck in the fridge so I'm not sure what your issue is with fridge sprouting. I just put them in a paper towel and then in a zip lock and the fridge them. I actually forgot about some I'd done that with for months. months and months actually. I planted out the 3 seedlings that didn't die from my forgetfulness and they are doing great.

Here's a picture of my $4 cold frame idea.
I found a steal of a deal, but the concept seems good to me.
1)bins with and without lids
2)cut lid middle out carefully with a sharp razor
3)2nd bin goes on top, glue together with some strong epoxy.
I need to think about what soil I'll be adding and how to drain it.
Eventually I'd like to use these outside sunk into the ground as cold frames, I'm not sure they'll be fully rodent proof but should be at least gopher and mole proof which has been an issue for my young fruit seedlings.
The plan is to use these to start my nut/fruit seedlings then move to the garden for winter sowing and maybe cold weather greens.
Thoughts?

Russel: I'm using the same type of container except I'm not stacking them, just using 1 with a clear top lid. I have my hazelnut seeds in it. So far so good for me. I just have it sitting outside with some rock on top to keep it from blowing away.

Here is a pic of the planting of them. Daughter is eating dirt and son is scarifying seeds. Both dorky. They take after me there.

Update:
Chestnuts sprouting!
My unheated porch has recently gone from low 30's to mid 40' since we seem to have hit a really warm january here in MN.
I started some nitrogen fixers this weekend, nicking and soaking Black Locust, Honey Locust, Kentucky Coffee tree, Eleganus, along with some Yellow Horn and Japanese Raisin tree seeds. Those along with my Ginko seeds have been getting most of my attention in a sealed tupperware filled with peat moss on a warming pad under grow lights.
I also glued up the cold frames and have been observing tempature swings inside and outside them. Heat retention isn't great since they are empty, but in the sun they warmed up 10-20 degrees above outdoor conditions. I'm going to need to figure out venting, drainage, and soil for them soon because...
I have chestnuts sprouting! Yeah! Not a waste of money! These seeds also froze briefly which I was very concerned about so it shows some freeze resistance.
Sleeping Giant variety only yet which is interesting and concerning. SG is supposedly a chinese/japanese/american hybrid. I hope this doesn't mean the trees will be expecting spring in january. We'll see though won't we.
A quick but thorough inspection of the other seeds showed one apricot sprouting too but that's it, still nice to see. No mold issues anywhere which is nice.

I'll be bringing two of the cold frames inside to fill, vent, and add drainage to and then plant the SG chestnuts and probably some of the other seeds in one since I'll have room and want to encourage deep roots. I'll have to keep the planted one inside for awhile longer under lights but hope to get it outside within a month.
The filled but unplanted cold frame will be put outside for observation of tempature, freezing, over heating, etc.
I'll post pics once I get that all set up.
Have a good one!

Update:Testing my ingenuity
We'll it appears I am getting better at sprouting tree seeds. My experiment runs amok.
Chestnuts are sprouting, now maybe a quarter of the seeds of all varieties Layeroka, Sleeping Giant, and colossal. The unheated porch is back down into the low 30's which slows the sprouting and is giving me some time to figure out what to do with all these.
Almost all of the apricot seeds also have sprouted, of the 15 I had stratified, 9 have sprouted. He others look like they will too.
I started black locust and those ended up starting so easily after scarifying and soaking I may actually toss them and wait til spring to start a whole bunch of them.
The stars of my early indoor spring emergence however are the ginkgo, the yellowhorn, and the elaganus v. Oreintalis.
February looks cold, but i have been monitoring my Tupperware cold frame filled with soil outside and against a southern facing wall. It seems that with sun it can get 15-20 degrees warmer than outdoor temps. I plan on moving everything outside once nighttime temps remain at least in the 30's and I can add a blanket if needed. The daytime temps I can either un snap the lids, remove them, or keep them on depending. I just need to watch the skies for really hot sun.

Update:
Jungle.

I've gone into minimizing mode. All my chestnuts are sprouting, or growing, some growing tall.
Of the apricot seeds I stratified, only 2 have not germinated. I'll be doing a final germination data set at the end of all this but things have gone really well.
Antonkova apples all sprouted, quince, Chinese quince, eleganus var orientalis, black locust, ginkgo, Kentucky coffee tree, and yellowhorn fill out 1.5 of my tubs.
In the porch, pecans and hazels are splitting and I expect sprouting soon.
Some things have not shown life yet, but also haven't molded which is a good sign.

A few thoughts:
Black locust and Kentucky coffee tree seed sprouted so readily after scarifying and soaking that I will wait until late spring to do more, and just direct seed.

Chestnuts and apricots are showing quite the variation of growth habits already. Some chestnuts even have multiple sprouts which I thought was interesting.
My growing tubs are so far, a great idea. The roots are growing deep, the plants have space, and the soil retains moisture due to the large volume. The rub will be when I need to move them out of the basement.
Speaking of that, I intend to move them outside with the tub lids once nighttime temps are near freezing. Blankets and a south facing wall will have to be utilized until the ground thaws and I can harden my trees off.
Hoping for an early spring!(expecting to have ice on the ground til may)
Have a good one!

Update: Not tomatoes!

We've had a pretty mild spring here in the land of ice and snow, I needed to get my vegetable starts going so I moved my tree seedlings with their bubble cold frame outside. Still under an eave, and on a south facing wall, but outside nonetheless.
Results are impressive, It makes sense, but the tree seedlings are much better at handling cold and heat than my experience with tomatoes and peppers trying to harden them off.
The trees have handled 24 degree mornings inside their bubbles, thenthermometer inside the bubble read 34 that morning, I did add a blanket over the top but no tree damage, no death.

Seed sproutingwise I've added heart nut, hazel, and paw paw to my mix recently.
The pecans appear ready to go too. The hickories remain a concern, but it's an experiment so some failure is ok.

One really good observation is that my paw paw seeds froze solid in the mail. -17 F. I always read that frozen paw paw seeds are dead, NOPE!
3 of 7 sprouted vigorously this week. Good to know and observe. I'm thinking paw paw is a more cold hardy tree than it's maybe given credit for. My small 3 year old in the garden has survived 3 brutal winters here in MN, and now this frozen seed sprouts.

A few pictures,

A quick update:
I did end up bringing in the bubble cold frames inside this week. We had a string of nights in the low 20's and I didn't want to risk freezing eveything.
More of an issue honestly is the heat during the day, I cooked the seedlings one day last week, a few leaves lost but they recovered.
I have added wild plum to the mix now, although germination was poor overall for those.
A few observations:
Pecans split a month ago, but now some are molding and none have sent out radicals. I may experiment with heat to bring them out. All other seeds split and sent out radicals soon after.
Hazelnuts are all sprouting now, but I did remove the shell from some of them as an experiment per Deno's experiments. Those without shells seemed to grow faster from first radical to leaves.
All the nuts take awhile to send out shoots, definitely get their roots set before any leaves.

I thought I'd add a few observations
I'm becoming overwhelmed a bit with the amount of trees I was able to produce, so I'm hoping to compose a final scientific report with numbers and % at some point but it's possible I will only have protocols and observations.

I now have run through all the seeds I stratified, new to the list are the hickories and pecans.
Some tidbits of info/theories:
The seed source appears to greatly affect the germination %, it's obvious which seeds were fresh when they were sent to me, and which were stored for some amount of time before.
The hickories and pecans being the last to germinate likely it's not the cold stratification time but the warmer tempatures that are required to coax them out of their shells.
My plastic shell cold frames ended up working great when it was cold/frosty, but got way too hot, I'll have to rethink their design for the future, possibly with venting.
I've now transplanted out the first group of apricots, chestnuts, hazelnuts, antonkova apples, black locust, kentucky coffee tree, ginko, and chinese quince.
A few thoughts on each:
Apricots: biggest growers initially, but got leggy even under good light. Root structure was deep but not wide.

Chestnuts: Collosal was the biggest seedlings, with strong stems and bigger leaves, Sleeping giant was similar in size/structure. All the seedlings looked great.
The VERY interesting thing I observed was that the Layeroka chestnuts had a definite taproot in contrast with the wider roots of the other two varieties, but the seedling were smaller overall. All in all I was very surprised at the simplicity of starting chestnuts.

Hazelnuts: I had two types stratifying, Jefferson(open pollinated), and wild american, the wild ones didn't sprout, the Jeffersons all did. Growth was/is good on these.

Antonkova apples, grew great, no obvious taproot like the Layeroka chestnuts, but they are smaller seedling overall so we'll see not that they are in the ground.
They do seem to have some more vigor than other apple seedlings I've started. There's just something about them that seems resilient.

Black locust started with a bang, 1 inch seedling in a week and then did not really grow much. I'm thinking that direct seeding may be better for them, and I will be testing this out in my grove project. Although small, they did seem happy and had good roots on them. perhaps they will take off this summer.

Kentucky coffee tree: Sadly this one didn't like being grown in a container, some of the seedlings died after looking great for a few months. Another direct seed candidate. The root structure is interesting , very thick immediately under the stem, and then trailing off into the soil.

Ginko nut: I had 2 seedling make it into the ground, one has very large leaves and a thick stem, the other seemed leggy and frail. I have located a seed source on the University of MN campus now and I hope to collect my own fresh seed this fall to come into more of these trees.

Chinese quince: 100% germination after stratification, which is alot more chinese quince than I really had hoped for, we'll see if this one makes it through the winter in my climate, but it's a fun looking tree/fruit to add to the pile of diversity.

Here's the final germination info for my seed stratification experiment. I may still have a few nuts germinate but most look done.
I'll add pretreatment conditions, general time and temperature information, and comments for each tree/plant.
The experiment of trying different temperatures of my basement which was much more even cold, vs my porch which had intermittent warmth and cold made no difference. All the seeds that ended up germinating, did so under all conditions at the same time.
Peat moss v sphagnum moss also made no difference. I would recommend the peat moss though as it was alot easier to see the small white radicals of the smaller seeds especially.

Antonakova apple- Wash seed and soak 24 hours, stratified at 35-50 degrees F for 3 months, 95% of seeds sprouted in moist peat in ziploc with 6 holes punched for ventilation. Generally I would inspect the baggies for sprouting or mold every week or 2.
Apple seedlings are robust and doing well. Seed source FW Shumacher.

Quince(cydonia)-same conditions as apple, 2 of 8 seeds sprouted (25%) One early with the apples and one much later.
Very delicate leaves on the seedlings, almost velvety. Seed source Tradewinds

Medlar-Same conditions, no sprouting occurred after 6 months. No obvious molding, but seeds don't appear viable anymore.
Seed source FW shumacher

Chinese Quince-same conditions, 100% germination, early mold was not an issue. 9 of 10 sprouted early with the apple, one much later
Seedlings were robust with a waxy leaf. Seed source Tradewinds

Goumi- no germination occurred now 6 months out. No obvious issues, just didn't seem to germinate.

Akebia, both 3 and 5 leaf types-no germination occurred. All seeds molded early. I've tried this one several times now from different sources. I'm surprised Akebia is actually considered invasive some places. I may buy a plant someday, I like to try out vines. Seed source Tradewinds

Apricot(regular and manchurian)-Same pretreatment conditions, 99% germination after 3 months. I had one seed out of maybe 50 not germinate.
Seedlings raced to 1', I definitely would try direct sowing these in the future as the seedlings took up a ton of space inside and out competed smaller ones nearby.
seed source FW Schumacher

Wild plum-Same pretreatment conditions, 5 months before the majority of these germinated, although swelling and shell splitting was seen much earlier, 95% germination rate. I ended up planting these outside so the seedlings were not as robust as early as the apricots were, but i could see them being similar.
Seed source FW schumacher

The next group was soaked 48 hours with multiple water changes, stratified in 35 to 50 degrees F in peat moss in ziploc baggies with several holes punched through for ventilation.

Northern Pecan- Sprouted after 5 months, 50% germination rate. It's possible others will continue to germinate into the next weeks though. Radicals seem to get stuck sometimes and cannot split the shells.
Seed source FW schumacher

Kanza Pecan- Sprouted after 4 months, 50% germination rate although these had alot of molding, bright blue fuzzy mold from inside the shells, it did not appear to infect other viable seeds, but did make for a mess. These shells swelled and split much earlier than they germinated.
I wonder if pecans require more hydration during germination than I was able to provide?
Seed source Burnt Ridge

Shellbark hickory-Sprouting still after 5.5 months, so far 33% germination rate, but I expect more will sprout eventually.
Seed source Burnt Ridge

Jefferson hazelnut- Sprouted after 3-5 months, split shells earlier than that. 75% germination rate. I did remove the shells of 10 hazels and all of those germinated, although the hassle obviously wasn't worth it since the germination rate was high regardless.
Seed source Burnt Ridge

Hazelnut-Native and tree hazel-no germination, seeds didn't seem to react the same way as the jefferson hazels did to the soaking and stratification.
Seed source FW schumacher

Ginko- 50% germination rate, seedlings were quite variable in size and growth rates.
Seed source Tradewinds

Heartnut- 90% germination rate after 4-5 months
Seed source Fw Shumacher

Butternut- 25% germination rate after 5 months stratification, I could see more of these germinate too later this month.
Seed source FW schumacher

Cornelian cherry- No germination now 6 months out. I also tested this one outdoors as there was some info that the seed required freezing.
Interestingly the seed still looks ok, no mold, no shriveling. I will keep an eye on these and possibly they will sprout after another freeze next spring.
seed source FW schumacher

The only remaining group in this experiment was the chestnuts. I soaked them briefly and added them to the peat/sphagnum moss ziplocs. They were the first to sprout and had a 90% germination rate after a month in the 35-50 degree porch. Sleeping giant was the first to sprout, colossal next, then the layeroka.
Seedlings put down impressive roots and added 6'' to 2' of growth depending on the size of the nut.
seed source Burnt Ridge

Pawpaw seeds germinated after 2-3 months after freezing solid in the mail. 50% germination rate
seed source FW shumacher

Black locust, kentucky coffetree, and honey locust all had 100% germination rate as long as I clipped the seed with a nailclipper in the corner and soaked them 48 hrs.
locally foraged seed source
I was able to get a yellowhorn tree in this way too out of 4 seeds clipped, however it did not work with the japanese raisintree seeds I tried.
Seed source FW schumacher for both

If i were to design this all over again I would make the following changes:
Smaller "bubble" cold frames, the 4$ plastic cold frame bubble idea was a good one, but they ended up not having enough heat retention for freezing nights and heated up too much during sunny and warm days. If you live in a cloudy/cool climate I think they would work great.
The main issue though was transporting them around after filling them with soil. I'm a big strapping Minnesota man, but they were just too heavy and clumsy to be really transportable.

I would probably try more direct seeding than sprouting indoors. Again this will take some experimenting since some seeds likely won't live through the arctic winters here.

I would take on less. I really had no luck whatsoever stratifying seeds before this, none. It became more work than I like to put on myself to keep up with the seeds/seedlings.
I have a few selected trees I'd like to try for next year, but I think I'm going to take some time to consolidate what i have and prep things for future plantings.

I hope people got something from all this, it was my wintertime project and it definitely gave me some new knowledge on propagation of trees.

Well, I'm back at it for 2015-16. I'm focusing more on shrubs/bushes this winter with a heavy emphasis on Seaberry and other hedge type plants.
Seed list:
From Oikos tree crops:
Timburr hybrid Chestnuts- American hybrid, planted seedlings a few years back and they've done very well here.
Ecos Pear-Pie pear, direct seeding produced alot of healthy plants before they were decimated by gophers.
Hughes crabapple-I want to get some cider apples going, this was apparently a favorite of Thomas Jefferson for hard cider.
Sloe plum-Thorny hedge plant, plums seem to grow well on my property.
Dunbars plum-" "
Missouri gooseberry-I like the idea of adding some gooseberries to my property, more of a hedge/wild addition.
Big hip Rose-I love rose hips, I just haven't gotten any from my roses yet, maybe this species in a sunny hedge would produce. Plus thorns.
Moonrise Asian Pear-Supposed hangover remedy applications, worth a try.
Ussuri plum-Hardiest plum apparently, again plums seem to do well here for me.
Ecos American hazelnut- More genetics for my hazelnuts, the Ecos is an Oikos "selection" for hardiness and quality.

From Jiovi seaberry:
I got their food forest package
Seaberry- I have a long sunny area in the field I will be establishing a food hedge of seaberry and other things. I planted seedlings from Burnt ridge 2 years ago and they grow great, I expect a small crop next year and these seedlings will help increase genetic diversity and give me some seedling numbers to play with.
Elder berry-Blue-black-red-Rocky mountain:
I also have a shady, wet, mulched ridge I've build up with dead brush over the years, I'd like to utilize it and elderberry seem to be deerproof even with my high deer pressure. I'm becoming more convinced of elderberry's cold remedy power. It could become a niche crop for me someday.
Dog rose-Again with the rose hips, I want to get a handful of bushes if possible to harvest from. Genetics are good too.
Yellowhorn-Looking forward to seeing how these grow here, my seedling made it through the summer and fall fine.
Siberian Pea- I have plenty of nearby sourced seeds, I'll wait til spring and direct sow these as support plants in the hedges.
Bearberry-Unfamiliar with this plant, but I like the low growing aspect. Hopefully I can get some to sprout and add them to my orchard under the trees or beneath the hedges.

I'll be using the soak-plastic bag in peat moss stratification method for the most precious seeds, it worked last year very well. I've also got a strategy for growing others I'll get into eventually in this thread involving stacking coffee cans.
I also direct seeded the elderberries, as well as dog rose, some seaberry, and pears.

UPDATE: As of 11/15/15
I already have some things sprouting. My system is better setup this year for sustaining things so I'm ok with it but 2 of my 10 chestnuts are already sprouting without any stratification. The seaberries also came pre-stratified which I was unaware of, nonetheless I have not wasted money since I'm getting things growing already. The green under my grow lights helps with my seasonal depression too so an early sprouting is ok.
Cheers!