STRATIFICATION, SCARIFICATION. Seed Sprouting

[897tgigvib]

This can be an important gardening topic so I capitalized it.

We can I suppose each understand these things differently, but...

Many perennials, small herbaceous plants up to the hugest trees have special requirements that have to be met before the seeds they produce will sprout.

Why? Why would nature have it like that?

Well, there are some good reasons, and I'll try to tackle them, but lots of folks here can say why better than me I'm sure.

These days us humans have taken plants from one climate region and grow them in other climates. It's easy to forget that.

When an Apple tree for example drops its apples in September or so, if those seeds sprouted immediately, or in October or November, they'd be wanting to start growing...in the middle of winter. And they couldn't. Light's not right. Temperature's not right. Timing's not right either because winter time is when they are supposed to be dormant. A little seedling with its Cotyledons and maybe a couple little leaves is not a very prime candidate for surviving winter dormancy.

Nature evolved them to be able to wait. How? Well, seems one easy way is those that did not waste their seeds that sprouted too soon were the ones that left descendents. Those that made seeds that sprouted too soon did not leave many progeny.

The way was built into the seeds. They got something sealing them from soaking up sprouting moisture, and some kind of seal that goes away while they freeze and thaw a few times. (I'm guessing.) What it is I don't know.

{I bet Ridge or Smart Red, or Thistle or someone will know}

So, Lots of Perennials evolved (or were created) that way. I suppose the exact mechanism of what happens in the seed as it thaws and freezes may be different for different Families of perennials, but it is true that lots of perennials are this way.

They call the process of freezing and thawing the seeds that need it, STRATIFICATION.

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Some other perennials make seeds that need to get cracked or scratched before they will sprout, or they even might need a BATH IN ACID! Yep. Some plants evolved (or were created) so that their seeds would get eaten, but survive getting eaten. Why? So that the animal would take the seeds and plant them somewhere away from the mother plant. That helps spread their territory. So, those plants that made strong tough seeds inside nice tempting fruits made progeny that spread far and wide, while related plants that made easier sprouting seeds in less tempting fruit might have progeny right near the mother plant.

They call this SCARIFYING.

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They sure come up with strange words for these things, but that's kind of the basics of it.

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Some plants need their seed to be lightly burned before sprouting!

 

[digitS']

A couple things that I can comment on that probably won't add much and certainly not explain how seed dormancy is broken, Marshall. Really, my comments are observations and, I hope, kind of fun.

There are wild Klamath Plums not all that far north of where you are. However, they aren't here - except, at the edge of my big veggie garden. The seed for that old tree may have arrived with a bird but I don't know of a bird that eats plums whole!

I think it blooms too soon, cued by hours of daylight that don't fit with the old plum's "thinking" about the time of a frost-free season this far north. There are about a dozen fruits on it each year and they are well back in the foliage - the flowers having been protected from the frosts. So, the seed drops directly under the tree. I've been there for 7 years, I believe, and have yet to see a seedling!

My guess is that the plum has to have a "good" year when fruit develops all the way out where the fruit falls at the "drip line" and where the seedlings would have a chance to grow without being robbed of sunlight and soil moisture. It may never happen.

Another possibility is that a coyote will eat those plums. I once saw some coyote droppings that were packed full of plum seeds! It was painful even to look at!!! I'm quite sure that they weren't Klamath Plum seeds but domestic plums. With so few plums under that tree and, probably, only an occasional coyote coming thru - that's not gonna give that tree a chance to have offspring either.

Returning to the mystery of how that plum tree got where it now grows is the idea that the seed passed thru a coyote that ate plums in southeastern Oregon and high-tailed it north at a dead run. I'll say that the odds were not in that coyote's favor that he could carry that seed so far but . . . we will never know .

Steve

 

[journey11]

Marshall, here's a technical article on it you might enjoy. From what I could find, there is still little known about how exactly the seed knows when the break dormancy, but this article suggests that it has a lot to do with moisture levels, plant hormones and genetic controls and some seeds may also need time to complete their maturation while in dormancy.

I was just thinking about this today in regards to some lettuce seed I had planted too early and assumed it was no good. Two lettuce plants sprouted about a month or two ago (don't remember exactly). (Maybe they were mutants...) But just this week I've been finding baby lettuce seedlings popping up everywhere. They knew when they wanted to sprout. Unfortunately, we are due to see our first frost in the coming week, so I guess I'll be making a low tunnel for them. Apparently there is a warm stratification needed by some types of seeds (lettuce being one of them) and they won't sprout just any ol' time you stick them in the dirt until they've felt that warm spell first. I'd noticed that happen with seeds from spring lettuce that I had allowed to go to seed--that they would just lie there and not sprout until late fall. But I hadn't noticed it with seeds directly from a packet. I wonder if those are stratified before you buy them usually? These red romaine I had planted I got from Baker Creek.

 

[Ridgerunner]

There you go Marshall, read Journeys article and give us the Cliff Notes. This stuff is hard to understand but I have faith in you and your ability to explain it in English.

I dont know the mechanisms that break dormancy. Probably many different things for different seeds, some chemical some mechanical.

Steve, for a seed to travel that far Id suspect a bird above anything else. I just cant see any seed staying in the digestive tract of a mammal that long. Somehow I dont think there is a river flowing your way to transport it.

 

[897tgigvib]

Digit, we have 3 kinds of Fir trees up here. (They actually don't know much about the Fir tree family and Genera, but to call them Fir trees is alright for now.) One of the kinds of Fir tree only grows at the higher altitudes and are not found here at the lake itself at about 2,000 feet. But there is one, a small 8 foot tree about 20 feet from my garden. In the case of this one it's easy to imagine the seed for it got here from bird poop or even Bear poop.

But your Klamath Plum. That's a long way from its normal home. I'd think a constipated bird must have been finally "relieved" to plant it that far from its normal range, or else there may have been other earlier accidental plantings of it years earlier inbetween and it worked its way north. Who knows? Maybe a vacationing person "planted" it, lol!

I am tempted to do the eating of some seeds myself but not something like an Apple or Plum seed. I can see Raspberry or Strawberry, but I don't feel like risking that intestinal problem, oh shoot what's it called, where something gets stuck in there, my aunt Neva has it, sumpnstuckinapocketoftheintestinesatosis.

 

[Smart Red]

"Diverticulitis . . . a common digestive disease which involves the formation of pouches (diverticula) within the bowel wall. This process is known as diverticulosis, and typically occurs within the large intestine, or colon, although it can occasionally occur in the small intestine as well. Diverticulitis results when one of these diverticula becomes inflamed." [Wikipedia]

You have to already have diverticula formed before a seed can cause a flare up of sumpnstuckinapocketoftheintestinesatosis. Consider all the watermelon seeds that have made their way through your. . . . . through you. I suspect it would be a neat experiment -- for someone else.

I know there is a tree in the Amazon that relies upon its fruits being eaten by a certain kind of fish. It will sit forever and never sprout without that trip down the intestine. Now that the fish are endangered, the tree is also becoming scarce. It is suggested that the extinction of the dodo bird caused the extinction of a tree that relied upon their intestinal voyage for germination. "The tambalacoque, also known as the "Dodo tree", was thought to be dying out on Mauritus, to which it is endemic. There were supposedly only 13 specimens left, all estimated to be about 300 years old. Stanley Temple hypothesised that it depended on the Dodo for its propagation, and that its seeds would germinate only after passing through the bird's digestive tract." [Wikipedia] Either Temple exaggerated or another animal also ate the fruit since there are (few, but) new tambalacoque trees growing today.

edited to quote sources

 

[hoodat]

Tomato seeds sprout best after they have gone through somethings digestive system. Of course they will also sprout where fruit dropped but if the plants depended entirely on that they wouldn't get much dissemination.
Locally we have quite a few native plant seeds that will lie dormant for years till a brush fire singes them, then they sprout quickly. Tecate cypress will not sprout at all if the pod doesn't get burned. The seeds are held tightly within a pod that is waterproofed by gum but when the pod is toasted it pops open and releases the seeds.

 

[Nyboy]

This spring I had a pile of composted horse manure delieveried to my house. The pile was much larger then I thought and a good size pile went unused. Mid summer tomato plants started growing out of it. The seeds must have overwintered in the pile. I thought strange frist frost will kill the plant but seeds can survive a harsh winter.

 

[digitS']

I remember as a young gardener reading in the newspaper one day about what was available at the sewage treatment plant.

Being an open minded young fellow, I showed up in the pickup on a bright, sunny spring morning. The guy I found out amongst the tanks pointed off to a corner of the yard. "It's over there!"

Kind of looked like a garden . . . . walked over . . . a little closer . . . looked again . . . ah, no . . . drove off.

Steve

 

[Nyboy]

Steve would you turn that down now?