Stratification Question

Vik250

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Hi,

I have a few quick naive questions:

1) Does every type of seed need stratification?

2) If the winter has already passed, and one is trying to germinate a seed in spring, is stratification still required?

Thank You 🙏 as Always!!
 

Shibui

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1) Does every type of seed need stratification?
Plants have adapted to survive in different environments. It is pointless for species in cold areas to have seed germinate as soon as they get wet because that's generally autumn then seedlings need to survive cold winter. Many of those species have adapted so that seed will not grow unless it has had a period of cold and wet then warm which means that the seeds now germinate in spring.
Other cold climate species have adapted by not shedding seed until spring so seed can't germinate in winter.
All that is a way of saying usually only species from cold climates need stratification - and then not all of them.

Species from arid and desert environments also can't afford all seeds to germinate with the first rain because it might dry out after and all dead = waste of effort. many arid species have developed hard seed coats so only a few germinate after first rain. Other seeds sit on the ground until either heat or time wears down the seed coat so water can penetrate. this means that some seed germinates each time rain comes so the tree is hedging its bets and chances are some will grow in good conditions and survive = success.
As growers we overcome that dormancy by either scratching the seeds (scarification) or heat treating (pour boiling water over the seeds) before planting to get better germination rates.

Species from fire prone areas have adapted to fit in with fire. Some retain seeds in hard cones until a fire goes through and triggers seed release - seed capsules are heated to release seeds. Others have inhibitors that stop germination until the seeds are burnt - seeds need heat treatment before sowing. Others are sensitive to chemicals in smoke and don't germinate until they get those chemicals - seeds are smoked or watered with smoke treated water before sowing.

Some species have hard coats or chemical inhibitors so seeds don't germinate unless they have had acid treatment as in passing through a bird or animal stomach. Usually species that have seeds in juicy fruit. Good strategy because the seeds are deposited with a neat package of fertilizer! These seeds germinate better after acid bath or leaching in running water for days/weeks depending on the inhibitor.

Other species have no inhibitors and seed grows as soon as it gets wet and warm enough. Those species are from milder climates or allow for huge death rates by producing huge numbers of seeds.

Many different strategies that plants have used to cope with the environment they have adapted to. As growers we need to know the strategies or make intelligent guesses at what germination inhibitors there may be.
The good news is that seeds that don't need treatment are rarely harmed by treatment so species that don't really need stratification will still germinate even if we stratify the seed so it is rare to harm seed by treatment, even if it over complicates the process.
Searching online will usually reveal which strategy to use with each individual species.
 

ShadyStump

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Think of the tree's native habitat.
If it's a tropical species, cold stratification isn't necessary.
I started a lemon from a seed out of a grocery store fruit this year, and all I did was leave it on top of my fridge until I was ready, then just put it in a pot of compost and mulch to grow. Took about 8 weeks to sprout.

There is such a thing as warm stratification, but that's essentially taken care of when you leave the seeds sitting in a jar in a closet while you wait until your ready to grow, or start cold stratifying. This step seems to be more optional with most species.

Many people do just plop their seeds in soil and set the whole thing outside for winter, letting nature do the work.
If you've just found the seed now and want to plant it, some of your stratification time may be taken care of, but if it didn't already start growing something it may be that the seed isn't viable.

The aim of cold stratifying is to imitate winter conditions in the ground. During this time many tree seeds will sprout a tiny root. When you stratify in your fridge in damp paper towel, this is usually what you're waiting to see before you plant it in soil.

I'm still learning the particulars myself, so others may have more info.
 

Shibui

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2) If the winter has already passed, and one is trying to germinate a seed in spring, is stratification still required?
All depends on the species.
Those that are obligate stratification species meaning the seed rarely germinates unless it has been through a cold period just won't germinate until conditions have been met.
Species that don't really need stratification will just germinate when the seed is wet and warm.
Species with other germination inhibitors wont grow until those conditions are met.
From any batch of seed there's usually a small number that will still germinate without treatment - plants hedging their bets by taking a risk that may or may not pay off.
To get best germination seed is treated according to the needs of that particular species.
 

LittleDingus

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2) If the winter has already passed, and one is trying to germinate a seed in spring, is stratification still required?

A rule of thumb for temprate species: if seeds drop in the spring, stratification may not be necessary. If trees drop in the fall stratification a usually necessary...it's a defense mechanism to help ensure progeny delay germination until after conditions that would immediately kill them have passed. Why start germinating the week before that snowstorm that will certainly kill you...delay until conditions turn favorable for longer.

Tropicals rarely need stratification for this reason.

Just a rule of thumb...not a certaintude...
 

Vik250

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Hi Shibui, Shady and rest. Thank You so much for this vital information. I have a pretty clear picture now. Very sincere Thanks to all of you for the help 🙏🙏
 

Vik250

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1) no, every seed does not need stratification

2) depends on what seed you are trying to grow

A lot of times I refer to Sheffield seeds even if my seeds have not came from them. At the bottom of each seed page tells you the preparation needed. https://sheffields.com/seeds/Acer/campestre
Wow. What a site!! So much detailed information. Thank You 🙏 🙏
 

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