Commonly called Hinoki false cypress or Japanese white cedar, Chamaecyparis obtusa is an evergreen species of tree grown for its erect growth habit and fragrant bark. It thrives within U.S. Department of Agriculture plant hardiness zones 4 to 8, where it is widely grown as a landscape ornamental or bonsai specimen. Hinoki false cypress trees grow best from seeds, which germinate reliably if sown in mineral-based soil while still fresh. Although the seeds will germinate without pretreatment, they will sprout more reliably and perform better if cold stratified prior to sowing.
Gather Hinoki false cypress seeds in autumn after the spherical cones begin to dry out and turn brown. Snip off one or two cones from a healthy tree branch rather than picking them up off the ground. Choose cones that have not fully opened.
Place the cones inside a large paper bag. Fold the top closed. Set the bag in a warm, dry spot outdoors for two weeks. Shake the bag periodically to knock loose the seeds. Collect the seeds from the bottom of the bag and discard the empty cones.
Soak the Hinoki false cypress seeds in water for 24 hours to hydrate the viable seeds and separate the inviable seeds. Discard any seeds that float to the surface of the water since they will not germinate reliably. Gather and sow the seeds that sink.
Fill a 1-quart sealable plastic bag with moistened sphagnum moss. Fold the seeds in a sheet of paper towel. Tuck the paper towel into the sphagnum moss so it is completely covered. Seal the bag and store it inside the refrigerator for two months. Remoisten the sphagnum moss whenever it is almost dry.
Prepare planting containers for the Hinoki false cypress seeds once the cold stratification period has ended. Fill 4-inch greenhouse pots with a mixture of 3 parts medium-grit sand, 2 parts loam and 1 part perlite or vermiculite. Saturate the mixture with water, then let it drain for 15 minutes before sowing.
Sow two Hinoki false cypress seeds in each pot. Press the seeds onto the surface of the sand mixture to anchor them. Sprinkle a scant, 1/8-inch-thick layer of sand over the seeds so they are covered but still slightly exposed to the light. Mist the sand heavily to settle it.
Place the potted Hinoki false cypress seeds inside a lightly shaded cold frame or on a porch with southern exposure. Warm the pots to 70 degrees Fahrenheit using a germination mat if daytime temperatures stay consistently below 65 degrees Fahrenheit.
Maintain constant moisture on the surface of the sand mixture. Mist the pots until the sand feels moderately moist in the top inch. Do not let the sand dry out completely on the surface since the Hinoki false cypress seeds will enter dormancy.
Watch for germination in three months, but don't be surprised if many of the seeds take up to two years to sprout. Move the pots with the emerging seedlings to a lightly shaded, sheltered area of the garden to continue growing.
Grow the Hinoki false cypress seedlings under light shade during their first summer. Provide 1 inch of water each week with additional water during periods of prolonged heat or drought. Acclimate them to direct sun in late summer.
Transplant the Hinoki false cypresses into a permanent bed in autumn of their first year. Choose a planting site with full sun or part shade and acidic, fast-draining soil. Avoid planting them close to buildings or other structures since their roots may cause damage.
Things You Will Need
- Pruning shears
- Paper bag
- 1-quart sealable plastic bag
- Sphagnum moss
- Paper towel
- 4-inch greenhouse pots
- Medium-grit sand
- Spray bottle
- Cold frame
- Germination mat
- Always use pots with at least two drainage holes at the base.
- Cal Poly Urban Forest Ecosystems Institute: Hinoki False Cypress
- Texas A&M University Department of Agriculture: Propagation of Ornamental Trees, Shrubs and Woody Vines
- Sheffield's Seed Company: Hinoki Cypress
- Kootenay Local Agricultural Society: Tree and Shrub Seed Germination Information
- Alameda County Master Gardeners: Your Alameda County Garden Month-by-Month
- Jupiterimages/Photos.com/Getty Images