Acer palmatum, called Japanese Maple or Smooth Japanese Maple is a species of woody plant native to Japan, North Korea, South Korea, China, eastern Mongolia, and southeast Russia. Many different cultivars of this maple have been selected and they are grown worldwide for their attractive leaf shapes and colors.
They are highly sought after and are relatively costly trees given their size.
Grow Acer Palmatum from Seeds
Step 1. Gather the seed or buy your seed from a reputable specialist. Pinch the wings off of seed and place them on a plate or bowl. (Do not use paper plates.) Let them dry for 36 to 48 hours, no more than two full days.
Step 2. I use plastic butter bowls for this step. Fill a bowl with cool water (not cold). Place about 20 to 30 seed per bowl. Don't try to crowd more than that amount per bowl. Let these seed soak for 72 hours. Every 24 hours, you need to change the water, this part is very important; it helps keep fungus from beginning on the seed. Personally I do not use fungicides with the water, but you can if you feel like it may help. After the 72 hour period, the viable seed will sink to the bottom, seed that float can be discarded at this time.
Step 3. Deciduous tree seed have to be stratified, they have to be tricked into thinking they are going through the dormant winter season. They also need this period of time to store up energy for the final stage of breaking out of their shell.
For this step, I use brown paper towels. You know the kind you see at schools, hospitals, public restrooms etc. The reason is, these types of paper towels don't have as much loose fiber as the kitchen paper towels. (This also helps prevent fungus from forming).
Place the seed on a sheet of towel and (gently) pat all the moisture off of the seeds. Repeat until you are satisfied all the dampness has come off the seed.
Step 4. For this step, I use small Ziploc bags (snack size), sandwich bags are too big and may cause a problem with too much air locked in with the seed (air may aid in the beginning of fungus problems)
Place the 20 or more seeds, no more than 30 in the bag and begin to roll toward the open end to dispel most of the air. Zip it closed. Important: Place the bags in your refrigerator in the lettuce crisper or veggie drawer. The temperature in these compartments usually stays at a constant. You need to check it with a thermometer and make sure it is between 37 and 40 degrees Fahrenheit (~ 3 to 4 degrees Celsius). The seeds must stay at this temperature for 90 days. About once every 7 days, take the bag of seeds out and gently tap the condensation off the inside walls of the baggie. Place back in the refrigerator on the opposite side which the bag laid. Let them sleep and repeat the tapping off process every 7 days until the 90 day period is up.
Step 5. Seed gathering and stratification process puts the time frame in my area for around the first or second week of February. This of course will vary depending on where you live and when you want to start the stratification. If you live in a tropical region, it can be any time of the year. You are now ready to sow your seeds! I usually sow mine in a prepared bed outdoors. Seed trays will work if you don't have room outside. I prepare my beds with a starting mix that is made by a company named "Peters". I have tried many brands and this seems to work best for my needs. It does not form a crust from repeated watering, this is very important for seeds sprouting up. They will die if they can't break through to sunlight. Plant the seed and cover with soil only the depth of the diameter of the seed. Keep the seed slightly moist (not wet) until germination. Generally speaking, the ground temperature should be between 58 and 62 degrees Fahrenheit (~ 14 to 17 degrees Celsius) for the Acer palmatum to germinate, but I don't believe this to be a hard and fast rule.
With this recipe, you should be able to see your labors of the past ninety days become a successful beginning to growing these beautiful little trees.
The other tree species named in this article can be treated the same way as the Acer for starting your own specimens for bonsai. An extra step must be taken for the Crataegus, Pyracantha, and Cornus species. These seeds must have the flesh removed from around the seed. Place the seed in a bowl of room temp or lukewarm water, put a drop or two of dishwashing liquid in with the seed and water, let sit for 4 to 8 hours. Begin to gently squeeze the seed flesh away from the seed. Be sure and remove (all) of the fleshy part from the seed or you may otherwise cause a fungus to form on the seed. You are now ready to begin the same steps as for the Acer seed.
I have learned through several years of trial and error that this stratification process works very well. I hope it will help hobbyists wanting to grow plants from seed as much as it has helped me.