Plant propagation is the process of creating new plants from a parent plant, ensuring the offspring retains the parent’s desirable characteristics. Unlike annual plants, which are grown easily from seed, woody perennial fruit trees like plums require more specialized techniques to reproduce reliably. Standard seed methods do not consistently produce a quality fruit tree that bears desirable fruit. Understanding the specific biology of plum trees allows for the selection of the most effective propagation method.
Rooting Plum Cuttings
Rooting plum cuttings is a practical and widely used method for replicating a specific plum variety, relying on the tree’s natural ability to regenerate tissue. Softwood cuttings, taken during late spring or early summer when the wood is still flexible and green, offer the highest chance of success. These cuttings should be taken from healthy, non-flowering shoots, ideally in the morning when the stems are fully hydrated.
The cutting should be approximately six to eight inches long, containing several nodes, which are the points where leaves or buds emerge. Remove all the leaves from the bottom half of the cutting, leaving only a few at the tip to facilitate photosynthesis. This reduction minimizes water loss through transpiration while still allowing the plant to produce energy.
To stimulate root development, the cut end is dipped into a rooting hormone containing indole-3-butyric acid (IBA) or naphthaleneacetic acid (NAA). The treated cutting is then inserted into a sterile, well-draining medium like a mix of peat and perlite or coarse sand. This sterile environment prevents fungal pathogens from attacking the wound site before healing can occur.
The newly planted cuttings require a high-humidity environment and consistent moisture to prevent desiccation before roots form. Placing the container under a plastic dome or inside a clear plastic bag helps maintain this humid microclimate. The cuttings should be kept in a location receiving bright, indirect light, avoiding direct, intense sunlight that could scorch the tender leaves.
Grafting Techniques for True-to-Type Plums
Grafting is the technique required to ensure a new plum tree is genetically identical to the parent, guaranteeing that the fruit produced is true-to-type. This method joins a small segment of the desired variety, called the scion, onto a separate, established root system known as the rootstock. The rootstock provides a hardy foundation, often selected for characteristics like disease resistance or specific growth size, while the scion dictates fruit characteristics.
One of the most reliable methods for plums is the whip-and-tongue graft, performed in late winter or early spring while both the scion wood and rootstock are still dormant. This technique involves making matching diagonal cuts on both pieces, followed by a small, interlocking downward cut, forming a “tongue.” This interlocking fit provides maximum surface area contact and physical stability.
Alternatively, T-budding is a common summer technique that uses a single bud, rather than a full scion stick, from the desired plum variety. A T-shaped incision is made through the bark of the rootstock, and the bud, along with a small shield of bark, is inserted beneath the flaps. This method is successful when the rootstock is actively growing and the bark easily ” slips” from the wood.
The success of any grafting technique depends entirely on the precise alignment of the cambium layers of the scion and the rootstock. The cambium is the thin, green layer of actively dividing cells just beneath the bark responsible for the plant’s secondary growth and nutrient transport. Once aligned, the union must be immediately wrapped tightly with grafting tape or rubber bands to hold the pieces immobile and exclude air and moisture.
Using Suckers and Seeds as Alternative Methods
Plum trees produce shoots, known as suckers, that sprout directly from the root system or trunk. These suckers are genetically identical to the root system and can be separated to form a new tree through a process called division. To remove a sucker, carefully excavate the soil around its base and sever the connection to the parent plant, ensuring the shoot retains a small mass of its own fine roots for successful establishment.
This natural process is only effective for reproducing the desired plum variety if the parent tree was grown on its own roots and not grafted onto a different rootstock. If the parent was grafted, separating the sucker will only yield the rootstock variety, which may produce inferior fruit. Suckers should be transplanted immediately into a prepared container to minimize root shock.
Propagating plums from seed, by planting the pit, is the least predictable method for fruit production. Plum seeds carry a mix of genetic traits from both parent plants, meaning the resulting tree will not be a genetic clone of the fruit it came from. The seedling may take significantly longer, often five to ten years, to bear fruit, and the quality of that fruit is highly unpredictable.
Caring for Newly Propagated Plum Trees
Once a cutting has successfully rooted or a graft union has healed, the young plant must be gradually acclimated to the harsher outdoor environment through a process called hardening off. This transition involves slowly increasing the plant’s exposure to direct sunlight, wind, and temperature fluctuations over a period of seven to ten days. Skipping this step can shock the tender tissues and cause the new growth to wither rapidly.
After hardening off, the new plum tree can be transplanted into a larger pot or directly into its permanent location in the garden. Young trees require consistent moisture in the soil to support the developing root system, but they must not be allowed to sit in waterlogged conditions, which encourages root rot. During the first year, providing a protective barrier against common pests and extreme weather conditions, such as frost or intense sun scald, helps ensure long-term survival.