Germinating Japanese Maple Seeds
By Mark Fields
Older Japanese maples, 25 years
or older, tend to produce a large quantity of seed. The seeds of most varieties will ripen in the
fall. Keep a close eye on the tree as
fall approaches to watch for ripeness.
The seeds are ripe when they are completely brown. At that time you can easily remove them from
the mother tree. You can also wait until
their leaves fall, the same times the seeds fall, and try to gather them up
then. Picking them from the tree is the
preferred method since you won’t have to rifle through the leaves to get to the
seeds in your lawn or mulch.
After collecting them, the wing
should be removed from each seed. The
seeds them selves have an extremely hard shell coating in order to protect them
from the elements. Under normal
conditions, it would take two years for them to germinate naturally. The first winter the hard shell will begin to
soften due to the high moisture levels.
During the second winter, the shell will break open and the seeds will
begin to germinate. In most cases the
seeds won’t even survive the two years required to germinate. They will inevitably be mowed over, mulched
over, killed with the weeds when spraying or eaten by animals.
You have the option of shortening
this cycle if desired. After you pick
the seeds and remove the wings, place them in a paper bag. Then just store them in a cool dry place
until early February. The time of the
year may vary. Here in Indianapolis, I
have found that the first part of February is the ideal time. You will be sowing them after the danger of
frost has passed. This date is usually
after May 10th here in Indy.
Sometime during the first week or
two in February, remove the seeds from the paper bag and place them in a bowl. Add warm tap water to the bowl. Be careful that it is hot to the touch but
not boiling. Fill the bowl with enough
water that it will completely cover all of the seeds. You will notice that most all of the seeds
will float on top of the water. Use a spoon
to ensure that you get all of the seeds wet.
Most of them will remain floating.
Allow the seeds to remain in the bowl of water for around 24 hours. At that time you will notice that most of the
seed will have settled to the bottom.
The ones that remain floating are most likely not viable.
Pour the seeds through a
strainer. Place the seeds in a Zip-Lock
bag with a moist, but not soaking wet, mixture of sand and peat. I have used Metro Mix 570 or composted pine
bark fines with good results as well.
Seal the bag and punch some holes in the bag with a bamboo skewer or a
sharp pencil for some air circulation. I
usually spray a squirt or two of fungicide to prevent any molding. Place the bag in the refrigerator until you
are ready to sow them outdoors.
Prepare a planting bed in the
ground or a planting tray. In the ground
I usually mix in some peat and sand with the existing soil. Remove some of the mixture prior to sowing the
seeds and after sowing, place about ½ inch of soil over them and water the area
thoroughly. In a tray I have had good
luck using a sand and peat mixture or sifted pine bark fines. Fill the tray with the mixture ensuring that
you leave enough room to cover the seed with ½ inch of the mixture. Water thoroughly and allow to slightly dry
out between watering. Watering too often
will cause the seeds and the germinating seedlings to rot.
In either case, keep shaded to
prevent the sun from scorching the tender new growth. You can place a suspended 50% shade cloth
over the bed or tray to assist in this effort.
Japanese maples prefer a semi-shaded location.
The seedlings will start to
emerge in about 2 to 6 weeks. It is best
not to disturb them for at least a year, preferably two. This will allow the root system to develop sufficiently
to be safely transplanted. It is also a
good idea to wait until they are dormant to do this. I have transplanted them while they are
leafed after a year and a half and had fairly good luck. I recommend that you wait until they are
Using this method you will be
able to produce a large number of quality seedlings. If you don’t have the privilege of being able
to collect your own seed, various quantities are available on eBay, Sheffield’s
Seed or Misho Bonsai.