I want to start some maple trees from seed (indoors). What is the process that I need to follow? Do the seeds need to be soaked or put into cold storage before planting?

Thank you for the question Darrell!

Propagating maple (Acer spp.) from seed is not complicated, although variation in dormancy requirements exists between spring/early summer-seeding soft maples (red maple and silver maple) and late summer/early fall-seeding hard maples (sugar maple and black maple). Therefore, to answer your question, I did a little research on the three most common native Illinois maples:

Sugar Maple (Acer saccharum): Sugar maple seed matures in late summer or early fall; collect immediately upon ripening. Stratification required – sow seed at 0.25-1.00 inches in moist growing medium such as vermiculite, peat moss, or sand for a period of 40-90 days at 33-39 degrees Fahrenheit (place in refrigerator); upon development of first germinants, move all seed to warmer environment to increase germination rate. Place germinants in larger planting media when necessary.

Red Maple (Acer rubrum): Please note that red maple seed may or may not germinate without stratification (this variability in stratification is due to genetic differences in red maple populations). Red maple seed matures in spring or early summer; collect immediately upon ripening. If stratification is required; sow seed at 0.25-1.00 inches in moist growing medium such as vermiculite, peat moss, or sand for a period of 60-90 days at 33-39 degrees Fahrenheit (place in refrigerator); upon development of first germinants, move all seed to warmer environment to increase germination rate. Place germinants in larger planting media when necessary.

Silver Maple (Acer saccharinum): Silver maple seed matures in spring or early summer; collect immediately upon ripening. No stratification period required; sow seed at 0.25-1.00 inches in moist growing medium such as vermiculite, peat moss, or sand. Place germinants in larger planting media when necessary.

[Information from USDA Woody Plant Seed Manual]

Stratification – is the process of pretreating seeds to simulate natural conditions that a seed must endure before germination. Many seed species have what is called an embryonic dormancy and generally speaking will not sprout until this dormancy is broken (Wikipedia).

I have a dozen maple trees growing in pots on my patio. When should I transplant out of the pots into the yard. Do I need to do something to protect them through the winter?

Keep these young, delicate seedlings in the pots on your patio for the remainder of the year (i.e.,, it is too hot and too dry for successful transplanting this year).

Transplant the seedlings early next spring (March or April) and make sure they receive adequate water during the growing season.