Let’s focus on conifers to make the generalization easier.
And I know I’ve written this question poorly… My apologies.
How long (a time average, I know this is not going to be the same for every tree) will a seed be viable once it leaves the tree?
If it is in a cone and falls to the ground, does it have the potential to last longer than if it is separated from the cone?
I know a seed cannot last forever, but they do have a limited lifespan outside the cone, do they not?
My questions:
if I have a pine cone full of seeds on the tree, are the seeds viable as long as the cone is attached to the tree? So, if the cone opens on the tree and the seeds are distributed by the wind, for example, is this the best possible scenario for the seed’s success?
If the cone falls from the tree, and the seeds are distributed by a bird or other animal, do the seeds lose a certain amount of life? (I am sure this isn’t clear, but let’s say a seed in a cone connected to its tree has a life span of a month. A seed in a cone on the ground is no longer connected to the tree… so does the seed start losing its ability to survive as each day passes? Let’s say for each day the seed is out of the cone and not in the ground, it loses 2 days of viability. Is this the correct way to look at this?)
If I take a cone and retrieve the seeds myself, and put them in a plastic bag to plant later, how much time do I have? Can the seed be in the bag for a year? 6 months? a week? What determines this?
Another nugget of info I’m hoping to get from the TM is the following… is a seed a self-contained reproductive unit that can remain dormant until it’s planted and/or watered, or does it have a shelf-life that once passed, means the seed can never grow into a tree?
I hope this is at least somewhat clear. This is one of the worst questions I’ve ever read, and I wrote it. I’m embarrassed.
I know you’re looking for a general answer, but there just isn’t one. Some seeds may remain viable for years, even centuries - others need to reach suitable growing conditions within days or even hours after being shed. In very general terms, however, big and/or soft seeds tend to need planting quickly and small, hard seeds are often able to remain viable for a very long time, if the conditions are right.
It looks like you’re narrowing the question down to conifers (and presumably further, to pines). The seed will last longest in the cone, because it’s an environment that’s stable. Changes in humidity and temperature tend to reduce the storage life of seeds.
Storing them in a plastic bag is generally a bad idea. A paper bag in a cool, dry place is usually better, and in the case of your pine cones, in the cone, in a cool dry place is better still. They are dormant, but containing a living embryo - often in a state known as anhydrobiosis, where its metabolism is slowed to near standstill.
Seed viability lifetimes are going to be variable for any given species though - so it’s not as if they will all be capable of germination up until a point, then all dead the next day.
Thanks, Mangetout, for muddling through my question to give a coherent answer. I appreciate it!
So, the potential exists for a seed to be able to germinate long after it leaves the tree and/or cone…
What does the seed contain? It’s obviously a fertilized unit that is ready to grow given the right environmental factors. But is there also a nutrition source that permits it to “survive” outside those factors, or does it just exist in a suspended state of animation until it finds the favorable environmental factors to permit growth?
And here’s another question your response made me think of… if you are saying that a seed could last years or centuries if the conditions are right, do ALL seeds have that potential (i.e. given the perfect environmental parameters, the seed could last for centuries)?
Some conifers (trees with cones) have tightly sealed cones and actually germinate better after a fire. These seeds also do better when placed in a bare mineral soil. Wildfires that clear the underbrush, expose bare soil, and open the sealed cones are part of the life cycle for these pine forests.
“A unique characteristic of lodgepole pine is its serotinous cones. The cone scales can remain closed for several years because of a resin coating. During an intense fire this resin melts away allowing the cone scales to open, thus releasing the seed. After a fire, a massive number of seeds are released. An intense fire also exposes mineral soil to provide a good seed bed.”
You may be interested in the ongoing seed viability study at Michigan State University. In 1879, Professor Beal buried 20 bottles of seeds, planning to open one bottle every five years. The spacing has been increased to ten, then twenty years, with the most recent bottle unearthed in 2000. Here are the 100 year results and 80 year results papers (only abstracts without buying them). At 100 years, only a few species of the 20 buried were still viable:
Many (most??) seed contains substances called ‘inhibitors’ (forget actual names of the chemicals involved) that delay germination until the approximate time/season so the seed has best chance for survival. This is why many species of plants do not germinate immediately upon ‘falling’. Cold weather, wetness, and a number of other Nature-based things must occur to degrade/remove the inhibitors and allow the germination to commence. This is why, when I gather seed for growing baby trees, I must place said seed into my refrigerator for a month or two (varies per species) or do other ‘stratification’ things. It is not unusual to have to scratch or nick the seed coat of hard/larger seed to get moisture into the innards, so to speak. Otherwise, Nature may take years to ‘rot’ the seed enough for it to germinate.
‘Evolution’ has provided numerous different ‘requirements’ for seed germination to occur, and it can be a real pain to fool Mother Nature, but worth it in the end. I highly suggest you search out the particular species for specific storage/germination info as it varies widely, even amongst the different Pinus seed. I usually took the seed out of the cone(s), and always stored in plastic baggies with a tiny bit of moisture added to the handful or so of peat moss within - never failed me, and I usually had a high-% of germination. The worst is to over-wet the seed, IME, and when a baggie shows minimal condensation upon the inner surfaces when chilled, then its about the right level of moisture within. The idea is to keep the seed from drying, not to keep it ‘wet’ - and in an airtight container, it does not take much to maintain the moisture needed.
Enjoy the venture into learning of seed…pretty neat how Nature has taken care of getting through seasons reliably when a plant would otherwise die/fail at thriving from having no viable seed when the next growing season comes around!
There’s more to it, of course, but all of these answers should help you get on the right track, so to speak. I want to add that any Pinus species will require outdoor sun, so growing 'em indoors (beyond the first two needles anyways) is definitely a no-go, and I say this from hearing numerous folks asking me “Why did my baby pine die?” Just in case the plan was to grow-out those particular seed
This site www.evergreengardenworks.com/articles.htm can give you a good background - read the ‘dormancy’ especially. The author is VERY respected bonsai grower/maker and is pretty good at writing technical things ‘for Dummies’, and also has an interest in learning as much as possible about seed germination/inhibitors (somewhere he mentions a name of another ‘researcher’ that is worth looking for if your interest is there)
Thanks all for the great information and links. As many of you have guessed, I’ve been doing some experimenting on conifer seeds, Nothing formal, just something I’ve been working with the past 2-3 years. I’ve had little success, but then again, this isn’t my area of expertise, so it’s been slow going, and mostly guessing.
I have found it interesting when one of the stored seeds actually sprout, but that has been the rare occasion, not the norm. I noticed that some of the seeds I purchased at the nursery had a “use by” date, which started the interest in this topic in the first place. I really didn’t think about seeds having a “use by” date, so I figure for some species of plants, they’ve been able to figure this out to a point where they can stamp a date on the seed packet that is the latest you can plant a seed and expect it to germinate.
Thanks again for all of the great info. I’ll be reading as much as I can to see if I can figure out what, if anything, I can do to lengthen the time a conifer seed can be stored and successfully planted in the future.
Seeds for sale have a sell by date or use by date on the packages because they are packaged for that season and the germination rate for that season is put on the package. Seeds can be sold the next year if the germination rate is tested and the new rate and sell by date is placed over the old one.
You may have bad germination because you’re not providing a required condition for germination. Often seeds require a certain period of cold or other environmental condition to be met. You should look up the requirements for each species you wish to collect seed for and germinate. Most purchased seed has had the conditions met prior to sale so the gardener doesn’t have to do this.
Not really - I mean, not without some sort of elaborate preservation - for example, Acorns ripen and drop in the autumn - those from white oaks will germinate almost straight away and grow slowly through the winter - red oaks will germinate in the spring, but any that haven’t found themselves in the right place to germinate will rot or dry out and die - regardless of the optimality of storage conditions - they just don’t have the potential for long-term viability.
On the other hand (and as others have mentioned), the seeds of some pines may remain dormant in the closed cones for years or decades, until a forest fire causes the cones to open and primes the seeds for germination.
As I said though, as a general rule of thumb, big fleshy seeds (for example acorns, chestnuts, almonds, lychee stones, avocado pits) have quite limited viability, whereas small, hard seeds (for example, poplar) are often capable of very long periods of dormancy.
