A Complete Guide to Growing Kousa Dogwood Trees from Seed

The kousa dogwood (Cornus kousa) is a small deciduous tree that produces showy blooms and unique fruit. It is native to parts of Asia but has become a popular ornamental tree in many regions, including the United States. Kousa dogwoods are normally propagated by cuttings or grafting but growing them from seed is also possible for the patient careful gardener.

Overview of Kousa Dogwood Trees

Here is some background information on the kousa dogwood before we get into the details of growing it from seed

• Deciduous small tree or large shrub growing 15-30 feet tall and wide

• Native to Japan, Korea, and China

• Features 4-petaled white flowers in early summer

• Provides reddish-pink foliage in fall

• Produces pinkish-red aggregate fruit in late summer

• Grows best in full sun or partial shade

• Prefers moist, well-draining, acidic soil

• Offers interest year-round with flowers, fruit, foliage and branching pattern

When to Gather Kousa Dogwood Seeds

Kousa dogwood seeds form in late summer inside the pinkish-red fruit. Follow these tips for collecting seeds:

• Monitor fruits starting in early August for color change from green to red.

• Fruit should be harvested when they are fully ripe and soft in late August or September.

• Remove the pulp and separate out the true seeds, discarding any empty ones.

• Rinse cleaned seeds and allow to fully air dry before storing.

• Label seeds by date and store in an airtight container in the refrigerator.

How to Stratify Kousa Dogwood Seeds

Kousa dogwood seeds have a double dormancy that requires cold stratification to break before they will germinate. Here is the process:

• To start, soak cleaned seeds in room temperature water for 24-48 hours.

• Prepare a container with moist potting soil or damp paper towels.

• Mix seeds with the damp medium and store at 35-45°F for 60-90 days.

• Check periodically and keep mix moist but not soggy.

• After the initial cold stratification period, move to a warm spot around 60-70°F.

How to Germinate Stratified Kousa Dogwood Seeds

Once the cold stratification process is complete, the seeds need warm temperatures to trigger germination.

• Prepare containers with seed starting mix and moisten.

• Plant stratified seeds 1/4 inch deep in the soil.

• Cover containers with plastic wrap or dome lids to retain moisture.

• Provide bottom heat of 65-70°F and grow lights if needed.

• Expect seeds to germinate in 2-3 weeks. Remove covers once sprouted.

• Thin seedlings to 1 per cell or pot. Maintain even moisture and warmth.

Transplanting and Caring for Young Kousa Dogwoods

Kousa dogwood seedlings require close care when moved from germination into the garden:

• Allow seedlings to grow until they have 4-6 true leaves.

• Harden off plants for 7-10 days before transplanting outside in spring after the last frost.

• Space trees at least 6 feet apart in an area with full sun to partial shade.

• Prepare planting holes twice as wide as the root ball.

• Set root ball on firmly packed soil with the top at ground level. Backfill and water.

• Water deeply once per week in absence of rain the first year. Mulch to retain moisture.

• Protect young trees from deer, rodents and wind damage. Stake if needed for support.

Long-Term Care of Mature Kousa Dogwoods

With the proper long-term care, kousa dogwood trees grown from seed will thrive:

• Apply 2-4 inches of mulch around trees, keeping it away from trunks.

• Fertilize in early spring with a balanced organic fertilizer.

• Prune only for shaping and deadwood removal after trees are established.

• Monitor for signs of disease such as spots on leaves or canker on branches.

• Water during drought, providing about 1 inch of water per week.

• Protect trees from lawn equipment damage with mulch rings or edging.

Key Things to Know About Growing Kousa Dogwoods from Seed

Growing kousa dogwood trees from seed takes time and diligence but offers some advantages over propagation by cuttings. Here are the key takeaways:

• Stratification mimics natural overwintering seeds require to break dormancy.

• Bottom heat aids germination once stratification is complete.

• Consistent moisture is critical through germination and transplanting.

• Young seedlings require protection from weather, pests and mechanical damage.

• Mature trees still need occasional supplemental watering and pruning.

• Seed-grown trees develop a deep root system leading to stronger plants.

• Unique characteristics can develop in new seed-grown kousa dogwood trees.

Troubleshooting Common Kousa Dogwood Problems

Even with proper care, some issues may arise when growing kousa dogwoods from seed:

• Poor germination – Ensure thorough stratification and optimal soil temperatures.

• Leaf spots – Improve air circulation and avoid overhead watering.

• Branch canker – Prune affected branches and promote vigor with care.

• Leaf scorch – Mulch and water during drought to reduce moisture stress.

• Poor growth – May indicate improper planting depth, soil issues or disease.

Kousa dogwood is a beautiful ornamental tree suited to landscapes across most of the country. Growing kousa dogwoods from seed, while requiring patience and diligence, allows you to propagate new specimens with unique traits. Follow the recommendations in this guide for the best results in germinating, transplanting, and caring for your homegrown kousa dogwood trees.