A week ago we found ourselves at the doctors office for one of my children. Nothing major (this time), just a regular check up and physical so she could run cross country (Very cool that a 7 year old wants to run cross country!). After her appointment we left the doctor’s office and found a dogwood tree, Cornus kousa, that was loaded with fruit. To make a long story short (actually the rest of the story is below – otherwise there wouldn’t be a post) we gathered a small bunch of berries(drupes) that had already fallen to the ground and brought them home to try and grow.
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 Growing kousa dogwood from seed can be rewarding for a patient gardener This complete guide provides tips for harvesting, stratifying, germinating, transplanting, and caring for kousa dogwoods grown from seed.
Overview of Kousa Dogwood
- 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 complete guide for the best results in germinating, transplanting, and caring for your homegrown kousa dogwood trees.
Starting Cornus kousa Dogwood from Seeds
Dogwood seeds can be started in the fall by soaking and removing the fleshy outer coating and sowing directly in pots to overwinter outdoors. This allows them time for the natural changing seasons and cold fluctuations – stratification.
Cornus kousa is a dogwood that is native to Asia. It’s becoming more and more popular here in the U.S. due to its resistance to diseases like anthracnose which is brutal to our native dogwoods. In fact a number of cultivars are now on the market which are a cross between the native dogwood (Cornus florida) and the Kousa dogwood including one called ‘Appalachian Spring’ which was introduced by the University of Tennessee.
If you compare the drupes of the two types of dogwood (native and Asian) you will notice some big differences. Size is the most obvious with the Cornus kousa dogwood reaching about 3/4 of an inch in diameter where the C. florida dogwood drupes are about 1/4 to 1/2 inch. (You can see a picture of the cleaned C. florida seeds here) Our native dogwood has drupes that are elongated where the Kousa is spherical.
The native dogwoods bloom earlier than the Kousa dogwoods by several weeks. This gives the landscaper or gardener a nice option when planning spring flowering trees to ensure a succession of dogwood blooms. Plan for the natives first, hybrids second, then the Kousa dogwoods for about 4-6 weeks of dogwood blooms.
How to Grow Kousa Dogwood from Seed Start to Finish
FAQ
How do you plant kousa dogwood seeds?
First pour warm water on to the seeds and leave to cool for around 24 hours. The water must not be too hot or boiling or the seeds will be killed. Next prepare a free draining substrate into which the seeds are to be mixed, this can be a 50/50 mixture of compost and sharp sand, or perlite, vermiculite.
How many years does it take for a kousa dogwood to bloom?
Dogwoods often take five to seven years before they begin to bloom in earnest. The good news is that if it takes a while to bloom, it’s because the plant is happy and healthy rather than because it’s under stress, and should keep blooming away for years to come.
How do you germinate dogwood seeds?
When you are starting dogwood seed propagation, you’ll need to soak the seeds in water for a couple of days. All non-viable seeds will float to the top of the water and should be removed. Soaking makes it a snap to remove the external pulp, expediting dogwood seed germination.
How to propagate kousa dogwood?
Softwood cuttings thrive when snipped in late spring to early summer; hardwood cuttings prefer the stoic dormancy of late fall. The plant’s natural cycle is your cheat sheet for timing. Snip, dip, and stick—the mantra for cuttings. Choose healthy stems, dip in rooting hormone, and nestle into soil that’s just right.