Japanese Maple Seed
Propagation
This page shows how I germinate Japanese Maple seeds.  The
technique isn't really that hard...it just takes a lot of patience.
The most important part of being successful in germinating Japanese Maple seeds is to purchase fresh seed from the current
year's season. There are several seed dealers online that will give you the season the seed was gathered.  If they don't tell
you when the seed was gathered contact the dealer and ask.

Another thing that you should know, the seedlings may or may not be the same cultivar as the parent plant.  Most reputable
seed dealers will tell you the cultivar of the parent plant, but advise you that the seedlings may not be the same.  In other words
a true "Crimson Queen" parent may not produce seeds that produce the same  plant.  The only way to propagate a known JM
cultivar is to graft it on to good root stock grown from seed. Purchasing seeds from a known cultivar and expecting every
seedling to be the same as the parent plant is going to result in disappointment.
After I receive my seeds, I open the pack and inspect the seed.  It may or
may not have been de-winged by the seed company.  De-winging is not
required, but it makes picking out seeds that have germinated a little
easier and cleaner.
Soak the seed overnight in warm water.  Some growers recommend
soaking in hot water of 120 degrees. That's roughly the temperature of the
water temp out of the tap. It's okay for the water cool to room temperature
overnight.  This will help break down the hard outer shell of the seed
embryo.  Drain off the excess water after the 24 hour soak and put the
seed in a plastic baggy. A couple of holes punched in the bag helps with
air circulation and preventing mold. Mix in a little peat to help absorb a little
more of the water and retain moisture.  

You can also knick the seed shell with a knife or blade from a coping saw
to let moisture seep into the shell..

Seed needs to be stratified for 90 to 120 days in the refrigerator before
planting. They need to stay moist and not wet. Don't put them in the freezer.
This process mimics the natural winter that the seeds go through.

Some growers say it is beneficial to take the seeds out of the fridge and
set them out at room temperature every so often to further mimic the natural
ups and downs of outside winter temperatures.
Check the seeds after about 30, 60 and 90 days and check for mold and
proper moisture. Add a little water as needed.  After 90 days you might see
some of the seeds starting to germinate. The seed in the circle is
germinating. Notice the white root tip poking out of the seed shell.

Remove any germinating seeds and plant in moist, slightly acidic and well
draining potting mix.  Barely cover the seeds with about 1/8 inch of potting
soil. Some growers recommend that you sprinkle coarse sand or perlite
over the seeds rather than potting soil to make it easier for the seed leaves
to come through the surface. It is said to also reduce dampening off
disease.

Once they start germinating I check every other day for germinated seeds
and pot them up.  When you find a few seeds starting to germinate, the rest
will quickly follow.  
After a few days the seedling will begin to pop up.  Avoid the temptation to
pull off the seed shell to "help it along."  The chances of breaking the stem
are pretty good if you help.

At this point you seedlings are very delicate.  A good place for them is a
bright window in your house that receives indirect sun.

A 4" plastic pot should be a good size for the first year.  A good time for
moving to a larger container is after the JM goes dormant in the fall.

Avoid over watering.  Let the potting mix almost dry out before watering
again.  DO NOT ADD FERTILIZER FOR SEVERAL MONTHS.

Raising a JM in a container will require 1/2 strength fertilizer after its first
year. A slow release fertilizer at 1/4 to 1/2 strength will also work.
Save your seeds that didn't germinate. Keep them in a pot of potting mix  out doors. Some of the
seeds may germinate the following Spring.
I know there will be a few folks that have different techniques for growing JM's.  This works for me and I'm sticking by that.
This page was updated on 4-14-09.
Bridge Street Nursery
Half way between Walterville and Leaburg.
Springfield, Oregon