Seed Stratification. Outdoors or in fridge

[Themilkyway]

Hello,

I live in Vancouver, zone 8b and I am wondering if I need to stratify seeds in a fridge or can I get away with just stratifying them naturally outdoors. Some of the seeds I have are:

Chinese Elm
Chinese White Pine
Trident Maple
Japanese Black Pine
Korean Hornbeam
Japanese Quince

My questions are if I can naturally stratify, is now (early Fall) an acceptable time to sow them? What kind of soil mix would you use?
If I need to put them in a fridge, when is the best time to start that process? Do I need to try to aim for Spring time by the time 3 months is up?

Thank you for your time.

 

[It's Kev]

It depends on your area and USDA zone, maybe add that to your profile. If the trees you wanna grow are endemic to your area you can stratify outdoors, if they come from a colder area pop them in the fridge

 

[Mikecheck123]

Outdoors is always easier b/c you don't have to do anything or remember anything.

However, for very dry seed, it is often required to do warm stratification for a month or so before cold stratification. You could do that indoors over winter, but not outside. Otherwise, you'll be waiting a full season for germination.

 

[Shibui]

Outdoors seems to work better for me as well. If stratifying in the fridge make sure to disinfect seeds and media to reduce problems with mould.
These species have germinated well without stratification here: JBP, Japanese quince, Trident maple (fresh seed) - if your seed is purchased you'll probably need to do warm and cold strat to break deep dormancy.
I have not tried Chinese elm without stratification but suspect it will not need because some of its natural range is in warmer areas.
Japanese white pine has large, thick seed shells so germinates better after stratification or cracking the seeds. Not sure if that applies to Chinese white pine?
Have never germinated hornbeams.

Remember to protect seed from seed eaters when sowing outdoors. Mice, rats, squirrels, etc are really good at locating seed in the soil. Some birds will dig in seed trays.

 

[hampton]

I did not stratify my JBP seeds this year and had a germination rate of about 60%.

I have some American larch seeds coming that I intend to stratify outdoors over winter. We’ll see how things pan out come springtime. Seems a bit more fool proof than the fridge, particularly since larch is native to this area

 

[Wulfskaar]

I get almost 100% germination of JBP with only an overnight soak. No stratification.

 

[Crazy Diamond]

Elms usually dont need stratification at all

 

[penumbra]

Outdoors is always easier b/c you don't have to do anything or remember anything.

However, for very dry seed, it is often required to do warm stratification for a month or so before cold stratification. You could do that indoors over winter, but not outside. Otherwise, you'll be waiting a full season for germination.

I have found this to be very true of Japanese Maples. Most sources are not supplying fresh seed. Out of 450 JMS I planted outside in a protected seed bed last year, I had about 50 germinate. The seed was very dry.

 

[Doogliebop]

Hello,

I live in Vancouver, zone 8b and I am wondering if I need to stratify seeds in a fridge or can I get away with just stratifying them naturally outdoors. Some of the seeds I have are:

Chinese Elm
Chinese White Pine
Trident Maple
Japanese Black Pine
Korean Hornbeam
Japanese Quince

My questions are if I can naturally stratify, is now (early Fall) an acceptable time to sow them? What kind of soil mix would you use?
If I need to put them in a fridge, when is the best time to start that process? Do I need to try to aim for Spring time by the time 3 months is up?

Thank you for your time.

Hey how did your seed crop do? I was looking to see if Korean hornbeam seed had to be warm stratified before cold for germination.

 

[Themilkyway]

Hey how did your seed crop do? I was looking to see if Korean hornbeam seed had to be warm stratified before cold for germination.

Hi there, so far it’s not looking too good. I’d give it a few more weeks of warm weather over here for my outdoors seed to germinate.

For the Korean hornbeam, I followed the instructions here: https://bonsaisupply.ca/products/korean-hornbeam-carpinus-turczaninowii-bonsai-seeds

I did see some some germinating in September but they unfortunately got burnt by too much sun and all died. I wish you better luck and I hope this helps.