Sunday, November 17, 2013

Planting Tree Seeds - Stratification

This fall I've had a strange obsession with collecting various tree seeds (mostly acorns) for the purposes of cultivating and planting them myself.  Having never done this before, I'll share some notes and photos for those who may be interested in doing the same.  I'll preface anything more by saying that I'm not an expert, nor have I kept meticulous notes (at least by my standards).

This PDF from the University of Illinois has some great detail of the uses, characteristics, and cultivation of trees.  While it is focused on trees from Illinois (of course), the species listed are ubiquitous.  The four species that I've picked (varieties of oak, hickory, maple, and sugar gum) should all require some duration of stratification with the exception of white oaks (which I'm certain to have in my collection), which should germinate and sprout while being refrigerated.  What I've read about whites suggests that they can be directly planted in the fall, but since (a) I've lost tracked of what oaks I've collected and (b) I can't identify oaks by seed, then I'll stratify everything in the same conditions and for the same duration.

Basic steps I followed:

  1. Culled damaged seeds.  This includes acorns infested by an acorn weevil (see photo below)
  2. Prepped the seeds.  This involved:
    1. Removing caps from acorns
    2. Separating the sugar gum seeds from the "chaff" that came out of the gumballs
    3. Soaking the hickory nuts in warm water for several hours (they were all floaters)
  3. Mixed the dry vermiculite with water.
  4. Added the seeds to their respective zip locks bags then covered with an ample amount of moist vermiculite.
A few guidelines I will also follow:
  • There is probably an ideal stratification time and temperature for each type of tree.  In this case, they'll all be stored at whatever the average temp of my fridge is and for the same duration (probably about 90 days) -- I'm basically simulating a winter period.
  • I expect I'll need to add a little more water for some of the larger seeds.  They've likely gotten dried out being stored on my desk, so I expect they will absorb a decent amount of moisture.
  • I've read in multiple places online about using a "float test" for identifying viable acorns.  The sinkers are supposed to be the best candidates for germination.  I didn't follow this step.
  • Come late February or early March, I'll transfer the seeds out of baggies and into soil at room temperature.
L to R, top to bottom: samaras, acorns, acorns, acorns, acorns, hickory, acorns, hickory
Sugar gum seeds and "chaff" -- I had no idea this is how these things worked.  I left a green "gumball" on my desktop for no more than a week.  Once it dried out, this stuff started spilling out everywhere.
Hickory shell starting to open
Maple samaras 
Finished products ready for the fridge
Grub for an acorn weevil - I had kept some of the acorns in zip lock bags which apparently caused the grubs to evacuate the acorn.  I had another bag that I discarded entirely because it was full of grubs and crud. 
Discarded acorns -- obvious weevil holes

1 comment:

  1. Ben great post. Some day some of your little seeds will have grown to tall majestic trees. You have inspired me to try my hand at this next fall. My friend Louise is heading up a project at LoneStar Montgomery Community College Woodlands TX to plant a Mesozoic Garden(some call them living fossil gardens or dinosaur gardens). It has been fun for me to be loosely associated with it.