How to Grow a Maple Tree from Seeds
There are over a hundred different species of maple tree, and depending on the variety, they range between 30 and 150 feet tall. These trees are known and loved for their distinct foliage, hard wood, and syrup.
Essentially maple trees can thrive within the entire continental U.S. or anywhere in Asia or the Mediterranean between the 24th and 49th northern parallels. With many municipalities encouraging the growth of native trees, jump on board with these steps and grow your own maple tree from seeds.
Step 1 - Harvest
As maple fruit ripens, it turns green to yellow to brown. When fully ripe, the fruit eventually falls from the tall trees where it can be collected and sourced for seeds. Most maple seeds ripen in the autumn. However, some seeds ripen in late spring or early summer.
Step 2 - Stratify
Store the seeds over the winter in a refrigerator for more than 90 days but no more than 120 days. The temperature should be kept between 33 and 41 degrees Fahrenheit. Keep the seeds in a 50/50 mixture of sand and peat moss in a perforated plastic Ziploc bag .
The seeds of the silver and red maple don't need a period of stratification and can be planted immediately after harvesting. Other maple trees can also be planted immediately after harvesting (in the autumn), but they will have a better chance at germination if they are stored in refrigeration for a period of stratification before planting.
Step 3 - Plant
After the stratification, plant the seeds in 6 inch pots and keep them indoors until there is no longer any risk of frost occurring outdoors. Use a planting medium that combines peat moss, organic compost, vermiculite, and coarse sand for best results when planting seeds in a pot.
If you want to plant directly outside after stratification in late spring, store the seeds in a paper bag until 100 days before the end of the frost.
Seeds should be sown in a sandy loam, about 1/2 inch under the surface. Water regularly, allowing the ground to dry out before watering again.
Step 4 - Transplant
Once sprouted, seedlings should receive about 50-percent shade. If they are outside where they don't receive much natural shade, install a shade cloth or snow fence over the seedlings to provide it. You can transplant your seedlings outdoors once the frost has passed and when they're about 4 inches high or have developed their second set of "true" leaves.
Continue watering thoroughly, allowing the soil to dry completely between each watering cycle. Avoid over-watering your maple seeds or they will rot.
Saplings can be transplanted into a permanent location at 1-2 years of age.
Step 5 - Continued Care
As your maple saplings grow into proper trees, be prepared to prune and care for them. Even if their growth is slow or staggered, prune as you normally would and avoid topping or stubbing.
In a case where your seedling growth is incremental enough that they remain vulnerable when the next frost or winter comes, be prepared to transplant the seedlings into a pot with heavy mulch and bring them indoors.
While this will protect the young trees from the worst of the cold, you can't simply keep them inside all winter as you did when they were seeds in your refrigerator.
Mulch will keep the roots warm, but you should still return the plants to the outdoors for a short time each day in winter. These will "harden" the seedlings with the hope that you can eventually transition them to an outdoor shed or greenhouse to wait out the rest of the winter.