Growing a dogwood tree, such as the flowering dogwood (Cornus florida), from seed is a prolonged project requiring patience and adherence to specific steps. The dogwood offers four-season interest, featuring showy spring blooms, vibrant fall color, and distinctive winter bark. Successfully propagating this tree requires guiding the seed through a natural cycle of dormancy and germination. This process bypasses quicker methods like cuttings or grafting.
Obtaining and Preparing the Seeds
The propagation journey begins with collecting the fruit. Dogwood seeds are encased in fleshy, berry-like drupes that ripen in late summer to early fall, typically between August and November. The fruit is ready for harvest when it develops its characteristic red coloration and can be easily removed.
After collection, the seeds require immediate and thorough cleaning. The pulp surrounding the seed contains chemical inhibitors that prevent the seed from sprouting. To remove this, soak the berries in water for a day or two to soften the flesh.
The softened pulp is manually removed, often by rubbing the seeds against a fine wire screen. A float test helps separate viable seeds; healthy seeds sink, while non-viable seeds and debris float and are discarded. The clean seeds must be dried slightly, but never allowed to dry out completely, as this compromises viability.
The Crucial Step of Stratification
Dogwood seeds possess an internal dormancy mechanism that must be broken before germination. This necessity is met through stratification, a process that mimics the natural cold and moist conditions of winter. This step cannot be skipped, as the hard seed coat and internal embryo require this conditioning.
One option is natural stratification, where clean seeds are sown directly into an outdoor seedbed in the fall. This allows the seeds to experience the full winter cycle, providing the necessary chilling period. A more controlled approach is artificial stratification, often done using a refrigerator.
For artificial stratification, the clean seeds are mixed with a slightly damp medium, such as peat moss, sand, or a soilless mix. The mixture should be moist but not saturated, resembling a wrung-out sponge, and placed inside a breathable plastic bag or sealed container. This container is stored in a refrigerator at 35 to 45 degrees Fahrenheit for 90 to 120 days (three to four months).
This cold, moist environment softens the seed’s outer shell and initiates hormonal changes within the embryo. Throughout this chilling period, the medium must be checked weekly to ensure it remains damp and to monitor for mold, which can be treated with fungicide. Once the cold period is complete, or small roots are observed emerging, the seeds are ready for planting.
Sowing and Initial Germination
Following stratification, the seeds are moved into a growing environment that encourages sprouting. The planting medium should be sterile and well-draining to prevent disease, such as a mix of three parts sand to one part peat moss or a commercial sterile potting mix. Use a shallow seed tray or small pots to ensure good drainage and avoid waterlogged conditions.
Each seed should be planted shallowly, typically about one-quarter to one-half inch deep. This depth provides enough cover for moisture retention while allowing the delicate seedling to emerge. After planting, the medium should be watered thoroughly but gently to settle the soil around the seed.
The container should be placed in a location that receives warm temperatures and indirect, filtered light. An ideal temperature for germination is between 65 and 75 degrees Fahrenheit. Even after stratification, emergence can be slow, taking two to six weeks for the first seedlings to break the soil surface.
Nurturing the Young Seedlings
Once the dogwood seeds have germinated, the tiny plants require meticulous care. Young seedlings thrive best under bright, filtered light that mimics their natural habitat as an understory tree. A spot receiving morning sun and afternoon shade is optimal, as direct, intense sunlight can scorch the leaves.
Consistent moisture is necessary during this early growth phase, as the small root systems are prone to drying out. The soil must be kept evenly moist, but not saturated, because overwatering can lead to the fungal disease known as damping-off. Water gently to avoid dislodging fragile seedlings, allowing the top layer of soil to dry slightly between applications.
Dogwood seedlings exhibit slow growth in their first year, often reaching only six to twelve inches in height. They may need to remain in their initial pots for one to two years to develop a robust root system before being moved to a permanent location. Before final transplanting, the young trees must undergo “hardening off,” which gradually acclimates them to outdoor elements.
This process involves moving the potted seedlings outdoors for increasingly longer periods over seven to fourteen days. Begin with an hour in a protected, shady spot, gradually increasing the time and exposure to dappled sunlight and gentle breezes. This slow transition strengthens the plant’s tissues and reduces the shock of being permanently moved outdoors.