Most Japanese Maple seeds ripen in the fall. Watch the tree and wait for the seeds to turn brown. The seeds are ready to be harvested when they are brown and can be easily removed from the tree.
The seeds are attached to a wing, it’s best to break the wing off before storing or planting the seeds. Japanese Maple seeds have a very hard outer coating as do many ornamental plants. Under natural conditions the seeds would have to be on the ground for almost two years before they would germinate. All that happens the first winter is the moisture softens the hard outer shell, and the second winter germination is beginning to take place.
In order for all of this to happen in the proper sequence so the seedlings actually sprout at a time of the year when freezing temperatures or hot summer sun doesn’t kill them, takes a tremendous amount of luck.
You can improve the odds by controlling some of these conditions, and shorten the cycle. Once you have picked the seeds and removed the wing just place them in a paper bag and store them in a cool dry place until you are ready for them. You don’t want to plant your seeds out in the spring until the danger of frost has past, here in the north May 15th is a safe bet.
If May 15th is your target date you should count backwards on the calendar 100 days. That will take you to about February 5th if my math is correct. On or about the 100th day prior to your target planting date, take the seeds and place them in a Styrofoam cup or other container that will withstand some hot water. Draw warm to hot water from your kitchen faucet and pour it over the seeds. Most of the seeds will float, just leave them in the water overnight as the water cools down. 24 hours later most of the seeds will have settled to the bottom of the cup.
Drain off the water. Place the seeds in a plastic bag with a mixture of sand and peat or other suitable growing mix. Even light potting soil will work. The peat or soil should be moist, but not soaking wet. Poke some holes in the bag so there is some air circulation, and place the bag in your refrigerator for a period of 100 days.
After 100 days you can plant the seeds outside. If you have timed it correctly, you should be at or close to your target planting date.
To plant the seeds just sow them on top of a bed of well drained topsoil or sterilized potting soil, and cover with approximately 3/8” of soil. Water them thoroughly, but allow the soil to dry out completely before watering thoroughly again. If you water them frequently, not only do you stand a chance of the seeds rotting from being too wet, but you will also keep them cool, which will slow down the germination process.
Once they start to germinate provide about 50% shade to keep the sun from burning them. Snow fence suspended about 30” above the bed will provide about 50% shade. Japanese Maples will tolerate some shade so it isn’t too important to transplant them too quickly.
Depending on how close together they are, you might be able to leave them in the same bed for one or two growing seasons. Don’t transplant until they are completely dormant.
Michael J. McGroarty is the author of this article. Visit his most
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 | Japanese Red Maple (acer palmatum 'red feather') - $ 250.00 This Japanese Red Maple has finely dissected palmette shaped leaves (deeply cut like the palm of a hand). Unlike many other red leaf varieties, the deeply saturated purple-red leaves of this Japanese Maple will not "bronze" or "green out" during the summer. A very beautiful tree that will lend a soft, delicate texture to a patio, deck, balcony or garden. Grafted. Deciduous. Keep outdoors. 19 years old. 34"x24"x24". Potted in a 14" ceramic green oval container as shown. Suitable 14.5"x10.5" humidity tray is recommended. To purchase add $11.95. Shipped via UPS ground - $95.00 |
 | Japanese Red Maplef (acer palmatum 'atropurpurea') - $ 195.00 Purplish-red becoming green in late summer, deeply lobed. Red fall color. Insignificant small reddish-purple flowers in May-June. Decideous. Keep outdoors. 7 tree group, 4-10 years old. 22"x16"x19". Potted in a 12" ceramic blue oval container as shown. Suitable 14.5"x10.5" humidity tray is recommended. To purchase add $11.95. Shipped via UPS ground - $49.95. |
 | Japanese Red Maple (acer palmatum 'atropurpurea') - $ 149.00 Purplish-red becoming green in late summer, deeply lobed. Red fall color. Insignificant small reddish-purple flowers in May-June. Decideous. Keep outdoors. 11 tree group, 5-9 years old. 21"x13"x20". Potted in a 16" ceramic oval brown container as shown. Shipped via UPS ground - $39.95. |
 | Japanese Red Maple - 17"x14"x19" (acer palmatum dissectum 'Red Filigree Lace') - $ 139.00 A relatively new variety with the most dissected or finely cut red foliage of any Maple. Deep maroon leaf color turns crimson in fall. Decideous. Keep outdoors. 11 years old. 17" x 14" x 19" Potted in a ceramic blue rectangular container 10'x8" as shown. Suitable 10.5"x14.5" humidity tray is recommended. To purchase add $11.95. Shipped via UPS ground - $34.95. Allow sufficient time for us to pack and ship your order. |
 | Japanese Red Maple (Acer Palmatum "Atropurpurea") - $ 59.95 Purplish-red becoming green in late summer, deeply lobed. Red fall color. Insignificant small reddish-purple flowers in May-June. Deciduous. Keep outdoors.Available 12 months a year. Will have no foliage during winter months. 7 years old. 14" tall. Suitable 6" x 8" humidity tray is recommended. To purchase add $3.50. Shipped UPS 2-3 days - $19.95. |
 | Japanese Red Maple - $ 24.95 The Japanese Red Maple tree, Acer Palmatum Autropurpeum, is by far, one of the most popular ornamental plants in the plant kingdom. This small deciduous tree is a very showy, versatile species. Japanese Red Maple trees are used as a single specimen or in borders or groupings. The leaves are reddish-purple in spring and again in fall. The Japanese Red Maple tree is used to create a unique bonsai tree. The classic Japanese maple has red-purple leaves which turn a brilliant red in autumn. |
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