Monday, September 8, 2014

Seed Stratification

Many seeds will not germinate well unless they are exposed to some kind of pretreatment.  That pretreatment is generically called "stratification" because the first pretreatments involved alternating layers of sand and seeds in a container (like a barrel) that was the left outside or buried in the fall only to be dug up and emptied in the spring.

Most woody plants that originated in temperate regions look for an event that simulates "winter".  That prevents them from germinating during the Indian Summer.  Typically, three or four months of moist, 40 Fahrenheit (5 C) will do the trick.

Some woody plants are pioneer species.  They typically demand full sunlight to survive.  Some of these species are fire activated.  They require heat to break-down their seed coat and initiate germination.  Black Locust is one of those species.  It is quite an act of faith to pour a quart (one liter) of boiling water over four ounces (100 grams) of seeds and to stir them for two minutes.  But that is what those seeds need to "convince" them that it is their turn on stage.

Berries that are typically eaten by birds can be very complicated.  The seeds will get scuffed up by grit in the gizzard, soaked in acid in the stomach and then deposited in a squirt of fertilizer...often on top of a cow pat.  Various nurserymen have developed wing-of-bat-eye-of-newt protocols that sort of work.  They often involve multiple cycles of warm and cold.  Rose seeds and hawthorn seeds fall into this catagory.

Hawthorn seeds




I spent the big money and bought an ounce (28 grams) of Crataegus pinnatifida seeds.  Sounds like a sporty Italian coupe, doesn't it?

Soaked in well water for two days with multiple changes of water.

These seeds are big!

May Theilgaard Watts wrote an excellent essay explaining how the tender hawthorn seedling is absolutely dependent on the cow-flop to repel the hungry cow until the seeding has had time to harden some thorns.  It also greatly enhances the fertility and water holding capability of the dirt around the roots of the hawthorn.  That essay can be found in her book Reading the Landscape of America.

If a Black Locust is genetically programmed to provide its seeds with a coating that demands fire, then it is within the bounds of possible that hawthorn seeds have a mechanism "looks" for poop.  Perhaps it is a coating on the seed that common fecal microbes can break down.  Perhaps it is a growth inhibitor that microbes can chew up and use for energy.

I am blessed to live in a place where scatalogical specimens from a wide range of species are readily available.

Cow-flop
Even as I type, this cow-flop is being rehydrated to the consistency of cake batter.  It will be mixed with grit and the hawthorn seeds and they will have four months of warm stratification.  Then the seeds will be washed out of the synthetic cow-flop and then cold stratified for another four months.  Then they will be planted out in flats.

This is how I intend to process all of the Hawthorn (Crataegus) seeds I collect this year.  This is probably not typical of what most retired guys do.  But it must be that I really enjoy stirring up....well...you know.

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