Fall/ Winter Sowing

[Phishstix]

Good afternoon folks,
So, the question is pretty straightforward, however I have found a lot of variance online in regards to what is “proper”.

Can I get most or all of my seeds in trays now and let nature take its course? There are some species I will try closer to spring, but would like to try getting more done early if they’re likely to survive. Can seeds be too cold too long? If outside do seeds need watering or leave it snow covered and let temp fluctuations do the watering?

I’m in zone 4a, so winters are long and potentially quite brutal -20c - -30c (or colder) for weeks on end.

What I’m working with-

Pines:
R mtn Bristlecone, Lacebark, Limber, Korean, Chinese white, Himalayan White, Siberian, Ponderosa, Jack

Maples:
Acer Palmatum v. Disectum, Mountain Maple, Red Maple, Rocky mtn Maple

Assorted:
Douglas Fir, Mountain Hemlock, Koyama Spruce, Burr Oak, Ohio Buckeye, Dawn Redwood, Giant Sequoia, Utah Juniper, Gingko

Ps. If anyone has success with Korean pine germination, I would love some tips. Going on year three with 0% success.

 

[czaczaja]

If you're sowing outside, just let them be, this is how they grow in nature. No harm in covering them with some net to stop birds/rodents getting desperate.
This year I've decided to sow all 'native' trees outside right after collecting the seeds as an experiment.
I've got oak, birch, ash, maple, fir, pine and many others sown directly into trays and left outside to germinate.
I already had a couple confused conifers germinate before winter even started
Having said that, -30 sounds quite cold so non-native trees might struggle.

 

[Wires_Guy_wires]

No harm in covering them with some net to stop birds/rodents getting desperate.

Make that a metal mesh and you're good. Because over here, nets don't stop the rodents.

 

[czaczaja]

Make that a metal mesh and you're good. Because over here, nets don't stop the rodents.

True. Might apply that myself. Last thing you want to find in spring is your seedlings eaten by mice.

 

[Leo in N E Illinois]

Using a wire mesh is important if sowing seed outside. I have lost much seed to squirrels and rodents over the years. Once I started putting a tight, emphasis on tight, screen on my Anderson flats, I stopped loosing seed to squirrels. Squirrels will pry and bend 1/4 galvanized wire mesh out of the way if it is not tied down at frequent enough intervals.

@Phishstix
Seed of pines in the "strobus" or 5 needle family, and in the bristlecone family must not be allowed to get too dry. They need cold moist stratification to germinate, so they do benefit from being sown outdoors in autumn. All the pines you listed except jack pine are more or less "white pines" or "5 needle pines", and would benefit from cold moist stratification. Jack pine does not need stratification, though it can be treated that way and will hold off sprouting until warm weather in spring. Lace bark pine, Pinus bungeana while it has only 3 needles, technically belongs to the 5 needle white pine group, or its own sub-group in the white pine group. Treat its seed as you would Japanese white pine seed.

Most "5 needle pine seed" lasts at most 18 months to 2 years stored cool and dry in refrigerator. Old seed, seed that is not freshly harvested is the main reason for failure to get germination of members of the 5 needle pine family. Most 2 needle pine seed will store well with good germination for 5 to 10 years in a refrigerator. Stored dry in an envelop on a desk at room temperature most seed looses viability in a matter of two months give or take.

If you use a refrigerator to stratify seed, and forget to plant out seed in spring, I know from experience, often seed will still be good the following spring. But there is a point at which viability will be lost. I don't know just when, and it will vary by species. Try not to forget seed in refrigerator more than one "winter" cycle. Stored cool and dry many species other than white pine family last quite a long time. Remember, seed of the family of white pines does not last much longer than 18 months to 2 years when stored in a refrigerator and only a month or so when stored at room temperatures.

Seed of black pines and red pine families, and Pinus contorta family, including jack pine can last 5 to 10 years stored cool and dry in refrigerator.

Korean pine is in the 5 needle pine family. germination issues are probably due to not getting fresh seed.

Maples: are a whole separate trick bag.
Maples do it all, and often from the same batch of seed. Some seed sprouts immediately, some needs just cold stratification, some needs warm stratification followed by cold stratification.
Which of the above often depends on moisture level of the seed when harvested.

Maples that ripen seed early in summer, often will have a fair percentage of seed sprout immediately. Same seed if moisture level drops, the seed dries out some, the seed will then need stratification, often warm moist stratification followed by cold moist stratification. My suggestion, when you get your maple seed put it in moist media outdoors, Mark the flat well, it may take up to 2 years for seed to germinate. Some will come right away, some not until the following year.

When I have time I'll get to you on the others, some like the fir just plant and they will sprout, others need care. In general plant outdoors now and they will sprout in spring if your protection against rodents was good enough to keep the varmints out of your seed flats.

 

[Leo in N E Illinois]

Interesting factoid - American hornbeam, Carpinus caroliniana - seed planted will not sprout for over one year. Seed needs a full summer as "warm stratification" followed by a winter "cold stratification" you won't see seedlings sprout until late spring the following year. So when planting Carpinus or Ostrya seed, mark your flats well, you will see nothing for a full year. As their "warm stratification" requirement is upwards of 3 months or so, unlike maples, where you can "fake" a maple with 3 or 4 weeks of warm stratification. You can't fake hornbeam into sprouting quickly.

 

[czaczaja]

Interesting factoid - American hornbeam, Carpinus caroliniana - seed planted will not sprout for over one year. Seed needs a full summer as "warm stratification" followed by a winter "cold stratification" you won't see seedlings sprout until late spring the following year. So when planting Carpinus or Ostrya seed, mark your flats well, you will see nothing for a full year. As their "warm stratification" requirement is upwards of 3 months or so, unlike maples, where you can "fake" a maple with 3 or 4 weeks of warm stratification. You can't fake hornbeam into sprouting quickly.

I heard some junipers are like that and take cold - warm - cold in order to germinate.