Rainier cherries are a prized sweet cherry variety, recognizable by their delicate golden-yellow skin highlighted with a red or pink blush. Starting a Rainier cherry tree from seed is a prolonged process requiring patience and specific horticultural techniques. This method involves preparing the seed, simulating a natural winter period, and nurturing the resulting seedling until it is ready for the garden.
Extracting and Cleaning the Cherry Pits
The first step involves separating the pit from the fruit flesh to prevent mold or fungal diseases during preparation. Thoroughly wash the pits under running water to remove all traces of sugary fruit pulp. Soaking the pits in room-temperature water for 24 hours helps loosen residue and allows you to discard floating pits, which often indicate a non-viable seed.
After cleaning and drying the pit, some gardeners carefully crack the hard shell to retrieve the inner seed, or kernel, before stratification. This step speeds up germination by allowing moisture to reach the seed’s embryo more quickly. If you choose to extract the inner seed, use a nutcracker or a small hammer with gentle pressure, taking care not to damage the soft, almond-shaped seed within.
Simulating Winter: The Cold Stratification Process
Cherry seeds require a prolonged period of cold and moisture to break dormancy. Cold stratification artificially recreates these winter conditions to prepare the seed for spring growth. This chilling period is a requirement for sweet cherry seeds to germinate successfully.
To stratify the seeds, place them in a sterile, slightly damp medium such as peat moss, clean sand, or a folded paper towel. The medium must be moist but not saturated, as excess water can cause the seeds to rot. Mix the seeds into the moist medium and place them inside a sealed plastic bag or container with ventilation holes, then store this package in a refrigerator.
The ideal temperature range is 34 to 40 degrees Fahrenheit (1 to 4 degrees Celsius). The required duration for sweet cherry seeds ranges from 90 to 120 days. Monitor the bag periodically to ensure the medium remains slightly moist and check for signs of mold growth or premature sprouting.
Sowing the Seeds and Nurturing Seedlings
Once cold stratification is complete, plant the prepared seeds in small pots indoors to give them a head start. Use a well-draining potting mix designed for seed starting, ensuring the containers have drainage holes to prevent waterlogging. Plant the seeds shallowly, about one inch (2.5 cm) deep, and cover them lightly with the medium.
Place the containers in a bright location that receives full sun, such as a sunny windowsill or under a grow light. Keep the soil evenly moist but avoid overwatering, which can lead to damping-off disease. Germination can vary widely, sometimes taking a few weeks or several months.
Once seedlings emerge, select the healthiest plant from each pot and remove the others to allow the strongest to thrive. Before permanent planting, the young trees must undergo hardening off to acclimate them to external conditions. This involves gradually exposing the seedlings to increasing periods of sunlight, wind, and cooler temperatures over seven to ten days.
After the last expected frost, when the seedlings are 10 to 12 inches tall, transplant them to a permanent location. Choose a spot in the garden that receives full sun and has rich, well-draining soil.
Understanding Genetic Variability and Time to Fruit
A significant factor when growing Rainier cherries from seed is the inherent genetic variability of the resulting tree. Because Rainier is a hybrid cultivar, its seed will not grow “true to type.” The resulting seedling will be a new, genetically unique tree, and the fruit it eventually produces is unlikely to be identical to the original Rainier cherry.
The fruit from a seed-grown tree may be smaller, less sweet, or possess other characteristics. This genetic uncertainty is why commercial orchards propagate cherry trees through grafting, which ensures a true clone of the parent tree. Furthermore, a seed-grown sweet cherry tree takes an extensive time to produce fruit, typically ranging from five to ten years. This timeline contrasts sharply with grafted cherry trees, which often begin bearing fruit within three to five years.