Growing a plum tree from the pit found in fruit is a rewarding project. This process requires specialized steps because the plum seed, or kernel, has a natural mechanism to prevent immediate germination. This survival strategy, known as dormancy, means the seed must be tricked into thinking it has survived a winter before it can sprout. Replicating the specific environmental conditions a plum seed needs is key to successfully growing your own stone fruit tree.
Preparing the Plum Pit for Planting
The initial step after extracting the pit is to thoroughly remove all traces of fruit flesh. Residual pulp contains sugars and moisture that encourage mold and fungal growth, which can destroy the seed during preparation. Cleaning the pit under running water and gently scrubbing it is usually sufficient.
Once clean, you can plant the entire pit or carefully extract the kernel inside. The hard outer shell, or endocarp, protects the seed but can also delay germination. If removing the kernel, allow the pit to dry for a few days on a sunny windowsill to make the shell easier to crack. A nutcracker or small hammer can gently break the shell to reveal the almond-shaped seed within. If you leave the kernel inside, ensure the pit is fully dry before stratification, as excess moisture encourages rot.
Simulating Winter: The Stratification Process
Plum seeds possess a deep dormancy, requiring a period of cold and moisture to trigger germination. This process, called cold stratification, mimics the conditions the pit experiences during winter. It signals to the embryo that the cold season has passed and growth can safely begin. Skipping this chilling period dramatically lowers the chances of successful sprouting.
To stratify the seed, place the cleaned kernel or pit in a medium that holds moisture without becoming soggy. Suitable materials include slightly dampened peat moss, sand, or a paper towel. Place the medium and the seed inside a sealed plastic bag or container, removing most of the air before sealing. This sealed environment maintains a consistent humidity level around the seed throughout the chilling period.
The bag must be placed into a refrigerator, maintaining a temperature between 34 and 40 degrees Fahrenheit (1 to 4 degrees Celsius). This range is optimal for breaking dormancy without freezing the seed. The plum seed requires a minimum of 60 to 90 days of consistent cold treatment before it is ready to germinate. Check the seeds periodically to ensure the medium remains moist and to remove any seeds showing signs of mold.
Planting the Prepared Seed and Initial Care
Once stratification is complete, the seed is ready for planting, especially if a small root has sprouted during cold storage. Select a container that is at least 6 inches deep and has drainage holes to prevent waterlogging. Fill the container with a well-draining seed-starting mix, which provides a light, airy environment for initial root growth.
Plant the stratified seed about one to two inches deep into the soil and cover it lightly. The soil must be kept consistently moist but never saturated, similar to a wrung-out sponge. Place the container in a location that receives at least six hours of bright, indirect sunlight daily. A temperature range between 65 and 75 degrees Fahrenheit is ideal for encouraging the first shoot above the soil line.
As the seedling grows, it needs regular watering to prevent the young roots from drying out. Protecting the emerging sprout from temperature extremes and potential pests is important during its first few months.
What to Expect from a Plum Grown from Seed
A tree grown from a plum pit will have a high degree of genetic variation. This means the fruit it eventually produces may not look or taste like the original fruit. Commercial plums are often complex hybrids, and their seeds carry a mix of genetic traits. The resulting fruit may be smaller, have a different color, or even be inedible.
The most significant commitment for growing a plum from seed is the waiting period for fruit production. Unlike trees grown from grafted cuttings, a seed-grown tree must first reach sexual maturity. The first harvest typically occurs anywhere from four to ten years after planting. This timeline depends heavily on the specific plum variety and the growing conditions.