How to Propagate the Star Magnolia

Star magnolia is the common name of Magnolia stellata, a species of deciduous flowering shrub native to Japan. The branches emerge from a short central trunk and create an open growth habit that will reach 15 to 20 feet in height at maturity. Leathery leaves emerge following a short blooming period in late winter, when masses of 4-inch-wide, star-shaped flowers line the naked branches. Gardeners often grow star magnolia as an ornamental shrub and many propagate especially attractive specimens at home from seed or cuttings. Star magnolias respond to both seed and cutting propagation, but cuttings produce faster and more reliable results.

Things You'll Need

• Utility knife
• Vacuum flask
• Potting soil
• Sharp river sand
• Perlite
• 4-inch plastic pot
• Heat mat
• Spray bottle
• 0.8-percent IBA (indole butyric acid) rooting powder

Instructions

Seed Propagation

1. Gather seeds from a healthy star magnolia tree in late summer. Nick the hull of each seed with a utility knife. Soak the seeds for 24 to 48 hours in a vacuum flask filled with 80-degree Fahrenheit water.

2. Prepare a sprouting pot for each star magnolia seed while they are soaking. Mix 2 parts potting soil, 1 part sharp river sand and 1 part perlite until thoroughly combined. Fill a 4-inch plastic pot with the soil mixture for each star magnolia seed.

3. Press the star magnolia seed 1/2 inch deep into the soil mixture. Cover it well. Water the seed with 1/4 cup of water.

4. Place the pot on a heat mat set to 65 degrees near a source of very bright sunlight. Keep the surface of the soil evenly moist at all times using a spray bottle. Watch for sprouting in 35 to 50 days.

5. Transplant the star magnolia seedling into a 1-gallon pot filled with garden soil once it grows to 4 inches in height. Keep the seedling warm and under bright light until spring, then plant it out in a sunny bed with moderately acidic soil once temperatures stay above 55 degrees at night.

Cutting Propagation

1. Prepare a rooting pot for the star magnolia cutting before gathering it. Fill a 4-inch plastic pot with a thoroughly combined mixture of 3 parts sharp river sand, 1 part potting soil and 1 part perlite. Wet the soil mixture with 1/2 cup of water.

2. Select a young, vigorous cutting from near the tip of a star magnolia branch in spring just after flowering. Measure 6 inches from the tip of the branch and sever it at a 45-degree angle using a utility knife.

3. Pinch off any leaves or leaf nodes from the lower half of the star magnolia cutting. Scrape away a narrow, 1-inch-long portion of bark from the base of the cutting using the utility knife. Treat the lower half of the cutting with 0.8-percent IBA rooting powder.

4. Insert the IBA-coated end of the star magnolia cutting 3 inches deep into the prepared rooting pot. Squeeze the soil tight around the base of the cutting.

5. Place the pot on a heat mat set to 80 degrees to prompt root production. Expose the star magnolia cutting to at least eight hours of very bright light per day, but limit direct sunlight exposure to no more than two hours per day. Mist the foliage daily with a spray bottle.

6. Check for roots in six to 12 weeks. Tug on the base of the cutting to test for movement. Movement indicates the cutting has not sufficiently rooted.

7. Transplant the star magnolia sapling to a large container or plant it outdoors in a permanent bed three weeks after rooting or once it begins to produce new leaves at the crown.

References

• "American Horticultural Society Plant Propagation: The Fully Illustrated Plant-by-Plant Manual of Practical Techniques"; Alan Toogood; 1999