Plum trees transition from delicate blossoms to juicy fruits. Understanding the distinct growth stages, from flower to fruit, helps in providing optimal care and anticipating the harvest. This journey involves several transformations, each important for the development of healthy, flavorful plums. Knowing what to expect at each phase allows growers to support their trees effectively.
Flowering and Pollination
Plum trees begin their annual cycle with blossoms in early spring, often before leaves fully unfurl. These white or pink flowers signal the start of the reproductive phase. The flowering period usually lasts one to two weeks, during which pollination must occur for fruit development. Bees and other insects play a role in transferring pollen.
While some plum varieties are self-fertile, meaning they can produce fruit with their own pollen, many others are self-sterile or partially self-fertile and require cross-pollination from a compatible plum variety. For self-sterile varieties, a different plum tree that flowers at a similar time must be planted nearby for successful fruit set. Protecting these early blossoms from late spring frosts is also important, as cold temperatures can damage flowers and prevent fruit development.
Fruit Set and Early Development
Following pollination, the plum flower transforms into a tiny fruit. This initial phase, known as fruit set, is characterized by many small, immature fruits forming where blossoms once were. After fruit set, plum trees often undergo a natural thinning process, commonly called “June drop,” in late spring or early summer. During June drop, the tree sheds excess small fruits, often those not adequately pollinated or competing for nutrients.
This natural thinning ensures remaining fruit have sufficient resources to develop fully, preventing overbearing that can lead to smaller, lower-quality fruit. Growers can further enhance fruit quality and size by manually thinning young plums. This practice helps space out fruit on branches, allowing each plum more room and access to nutrients for optimal growth.
Pit Hardening and Rapid Growth
After fruit set and natural thinning, plum fruits enter a period of significant growth, rapidly increasing in size. This stage is marked by the internal development and hardening of the pit. The pit begins to harden approximately 30 days after fertilization, signifying the beginning of the fruit’s second developmental stage. During this time, the tree channels energy and nutrients into the developing fruit, leading to a noticeable expansion of the plum’s flesh.
While the pit is hardening, the fruit’s overall size increase may slow temporarily. However, the final stage of plum development sees another surge of rapid growth, primarily in the skin and flesh, typically four to six weeks before harvest. This rapid expansion helps the plum reach its mature size and accumulate sugars and moisture.
Ripening and Maturation
The final stages of plum development involve changes that transform the fruit into its ripe form. During this period, plums acquire their color, which can range from yellow and red to deep purple, depending on the variety. This color change is a key indicator of ripening. The flesh of the plum also begins to soften, shifting from a firm, often tart texture to a juicy, tender consistency.
The accumulation of sugars within the fruit contributes to its sweetness and flavor. As plums ripen, they also develop a fragrant aroma, particularly noticeable near the stem. The precise timing of this ripening stage can vary based on the specific plum variety and local climate conditions.
Harvesting Considerations
Determining the ideal time to harvest plums involves observing several indicators for optimal flavor and quality. The fruit’s color is a primary visual cue; plums change from green to their mature varietal color, such as yellow, red, or purple. However, color alone is not always sufficient, as some plums may develop full color before they are truly ripe.
Firmness is another important indicator; ripe plums should yield slightly to gentle pressure but not feel mushy. Gently twisting the plum from the stem is a good test; if it detaches easily, it is ready for harvest. Taste is the most reliable indicator, as ripe plums will be sweet and juicy with a balanced flavor. For short-term storage, plums can be kept in a cool, humid environment, such such as a refrigerator, where they may last for approximately two weeks at 32-40°F (0-4°C). Handling plums carefully during harvest is important to prevent bruising, which can lead to spoilage.