Hornbeam, Carpinus caroliniana, grows 25 to 30 feet tall with a wide canopy and a multi-stem growth pattern. This small tree originates in eastern North America. Plant hornbeam in the landscape to provide shade or to create a hedge or visual screen. The trees grow from Florida to Canada and are hardy to U.S. Department of Agriculture plant hardiness zones 3. Starting hornbeam from seed might not be the fastest way to add shade to the landscape, but the process of germinating and growing a tree from seed provides its own interest and rewards.
Lay a zip-top bag on it side and spread out a 1-inch layer of damp peat moss. Place two to three hornbeam seeds on the peat moss and cover with a second layer of damp peat moss 1 inch deep.
Place the bag into the refrigerator and keep it at 4.44 degrees Celsius for 18 weeks. The period of chilling breaks seed dormancy. Hornbeam seeds require the chilling period, called stratification, for successful germination.
Remove the seeds from the bag. Fill a seed flat with a mix of equal parts sand and peat moss. Dampen the mixture. Place the hornbeam seeds on the potting medium. Add additional potting medium to cover the seeds with 1/4 of the medium.
Place the seed flat in an area that gets dim filtered sunlight and remains between 12.8 and 21.1 degrees Celsius. Mist the seeds with water daily or every other day to keep the peat and sand mix consistently damp.
Move the seed flat to bright filtered light when the hornbeam seedlings emerge from the soil. Keep the mix damp during early growth stages with frequent light watering.
Transplant hornbeam seeds into individual 4-inch pots when they grow 2 inches tall. Fill the pots with potting soil. Lift the seedlings out of the seed flat.
Transplant the seedlings out into a 3-gallon pot when the seedlings grow 4 to 6 inches tall. Keep the seedlings in an area that gets filtered sunlight.
Transplant in spring the year following germination. Dig the hole slightly wider than the seedling's roots and plant it at the same depth as it was in the pot. Put a cage around the seedling to protect it from browsing animals and traffic until it grows large enough to withstand damage on its own.