I wanted to share my experience regarding seed stratification or lack of in my case. This pass fall I gathered a bunch of seeds from my backyard which I planned to grow in my small indoor greenhouse for my expending forest garden at home and for my parents cottage. I simply put the seeds in separate brown paper bags and dropped them in my seed box which was stored in the basement. I had planned to take them out in February to stratify them in preparation for March planting but completely forgot to do so. On March 4 I figured I had nothing to lose in trying and to my surprise everything started to germinate within a couple of week except for the grape and Lupin which take longer. *The attached picture is 12 days after planting.
I have always thought and read that cold hardy perennial needed a cold or freezing stratification period in order to geminated. My basement would have been around 12-15*C (53-59*F) and maybe on those very cold night it could have dropped to 10*C (50*F). Those temperature are not cold enough to mimic what the seeds would have experience in nature in a Zone 4/5.
So is stratification really necessary and has anyone else experience the same thing?
List of seeds I planted in the picture:
Blazing star (Liatris)
Hyssop (Hyssopus officinalis)
Kris, every plant has it's different needs for germination. Those that require stratification for germination will not sprout without it. Some need light, some need dark, some need specific temperature ranges, and thats just the way it is.
Keeping dry seeds at any temperature is not stratification, which can only happen if the seeds are moist. In my experience most annuals will sprout quickly, it's mostly the perennials which make special demands. I once saw a link here on the forum for a 3 part PDF that the scientist who did extensive germination research allowed to be public for anyone to download. It's helped me immeasurably for a couple of years now. I'll see if I can find the link.
Many hardy trees do need stratification but not all. It also depends in varieties. But yes, stratification is mandatory for some species.
The seeds of apples from the supermarket (common varieties) can germinate at room temperature. But siberian apple does need stratification for example.
Also, the duration of stratification varies WIDELY! And how it is done.
Good king henry or wax myrtle, hardy perennials, need about 3 weeks of cold moist stratification. Trees like silverberry need 1 to as few months. Some species need longer. Some species still germinate without stratification but germination is enhanced by it (crambe for instance). This is just my empirical experience.
Lettuce and asparagus do not really need stratification but benefit from germinating during or after a colder period, and 10ºC is just around fine. But species need a colder shock.
Some species even need cycles of alternating cold and mild weather. Some species germinate well after a period in the fridge in a moist paper towel or in peatmoss within a plastic bag (for example, pecan, almond), but other species do not work like this (good king henry for example).
Furthermore, some seeds of same species readily germinate after treatment, others wait a bit longer. This ensures germination at different places and conditions, and enhances survival.
Also, seeds enjoy germinating in their most natural conditions. Sometimes seedlings might suffer or die, when they germinate after a cold treatment and are moved into a greenhouse, rather than been allowed to follow a natural gradual increase of temperature outdoors.
There are several species that I am still trying to cold stratify in order to be able to germinate them but so far I had no germination yet : walnuts, hazelnuts, aronia, amelanchier, and many other species.
Finally, it is possible to cheat and by using hormones, to skip cold stratification, though I have never been able to do that.
Seed germination can often be a tricky business but it is a really rewarding thing once you achieve it!
in Portugal, sheltered terraces facing eastwards, high water table, uphill original forest of pines, oaks and chestnuts. 2000m2
in Iceland: converted flat lawn, compacted poor soil, cold, windy, humid climate, cold, short summer. 50m2
I am aware that some seed need stratification in order to germinate. What I was trying to get at in my original post is it seems the majority of seeds may not need any type of stratification (cold in my case) and only a small selection of seeds require it. From what I read False Indigo requires a cold stratification yet it has germinate a few day ago without it. I am wondering if stratification only increase germination rate in most case but not really required.
A couple of comments (without specifically researching what you actually sowed):
First, there is a lot of misinformation and conflicting information out there about germination, so it its not surprising to find something germinate at warm or without stratification that you read /heard needed strat. Often what has been passed down as gospel is what worked for someone somewhere- doesn't mean it was necessary or the only option.
Second, stratification of many kinds is meant to break seed dormancy, and that dormancy can be variable even within geographical varieties of the same species, and at different ages of the same seed batch- some seeds will germinate easily if fresh, and not at all if not fresh or may need stratification, or temperature cycling if not fresh (some woodlanders, for example) , and others are the opposite- fresh seed is hard to germinate, but older seed germinates easily (this is true of some cacti). Some things are erratic germinators no matter what you do. So, numerous reports of different results for the same species could all be true.
Many things have an ideal germination trigger, but will germinate a few individuals under other circumstances.
Definitely there is nothing so simple as most perennials either needing or not needing stratification-- some families such as Asteraceae or Brassicaceae have relatively few perennial species needing strat (but they do have them!), other families like Liliaceae or Ranunculaceae seem to have few spp that don't need stratification, and often more complicated things like warm cold warm etc. i grow a lot of seed of natives, alpines, woodlanders, drylanders etc-- tons wont do anything with strat or cycling, tons of others will germinate easily at warm or coo with no strat.. not a few take a couple of years of outdoor temperature cycling.
So, you really need to research each individual species as much as possible, and some things you just have to try.. no generalisations will get you far at all...
Some people give unknown things a a few weeks at warm to see if they will germinate, and if they don't, they get cold. If doing that, you might want to give them only the average 4C recommended for strat ( some things need freeze/thaw cycles, but that is a different category, and time spent frozen solid is not really strat) since if your seed has been absorbing water for a couple of weeks and on the edge of germinating, freezing could kill it, some say.
edge of the boreal mixed woods zone, just east of the Rocky Mtn Foothills, z 2/3
My favorite is a chocolate cupcake with white frosting and tiny ad sprinkles.
Greenhouse of the Future ebook - now free for a while