How do you grow Chinese sweet plum (Sageretia thea)? Master these planting techniques for better growth
Chinese sweet plum (Sageretia thea) is certainly familiar to bonsai enthusiasts. As one of the "Seven Sages of Bonsai," Zhang Yongfa praised it in his poem: "Red buds fill the tree in spring, green shade like a canopy in summer, tiny flowers with faint fragrance in autumn, iron-like bones and gnarled branches in winter." The Chinese sweet plum's roots and trunk are unusual, and as a whole it appears vigorous and strong, classical and elegant, truly a top-grade bonsai.
But the Chinese sweet plum has another trait that gives people a headache: branch dieback. In a finished work, a branch may suddenly die, commonly known as "retiring after success." A perfectly good potted work, embodying years of the creator's effort, is nearly ruined because of localized branch dieback, which is truly distressing. The reason is that the Chinese sweet plum's branch and trunk cortex is relatively thin, and its nutrient transport is longitudinal, so its daily care and management have very high requirements.
1. Keep potted Chinese sweet plum growing vigorously.
The prerequisite for vigorous growth is branches emerging on all four sides of the trunk. When selecting and retaining structural branches on a sprouted stump, this point should be fully noted. Even useless branches at the tops of trunks and other branches outside the intended design should not be cut off all at once; wait until the tree's vigor recovers, then gradually remove them according to the design needs. If cut off all at once, partial dieback may occur, seriously affecting the stump's growth and appearance.
As everyone knows, balancing tree vigor is extremely important for the growth of a stump. Only when the stump's roots, trunk, branches and leaves all achieve vigorous all-around growth can a stump that suffered severe damage when the material was reshaped recover, thereby accumulating sufficient nutrients and preparing for future branch shaping and styling.
Branch training and styling of Chinese sweet plum: rely mainly on pruning, and use or avoid wire wrapping as much as possible. Because the Chinese sweet plum's cortex is very thin, wire wrapped around branches will seriously affect the branches' nutrient transport, and over time will cause the branches' growth to weaken and, if it continues, branch dieback is unavoidable. Finished Chinese sweet plum should also not be pruned excessively, at most twice a year: once during the plum rain season, and once preferably before budding. After leaf fall, if thorough pruning is done for viewing purposes, the tree should be brought indoors promptly before winter freezing, because exposed cut wounds will freeze in severe cold weather, damaging the buds near the cuts, or even freezing small branches to death and affecting normal budding the following year.
2. Potted Chinese sweet plum should avoid severe water loss.
Severe water loss is one of the main causes of branch dieback in potted Chinese sweet plum, so keeping the potting soil moist is extremely important for potted Chinese sweet plum. We all know that when a plant suffers severe water deficit, its cells lose turgor pressure, because transpiration water loss temporarily exceeds root water uptake. In other words, the water content in the potting soil equals or falls below the amount of water needed for transpiration, especially in the high-temperature summer season. After severe water loss, a potted Chinese sweet plum may recover normal leaf growth after rewatering, but it will inevitably cause some plant cells to die, resulting in a growth pause. Many bonsai friends have likely had this experience: after a potted Chinese sweet plum loses water and is rescued by rewatering, although it does not wither and die, for a long time afterward the wet-dry cycle of the potting soil noticeably lengthens and the number of waterings noticeably decreases. The reason is that after severe water loss, some cells in the roots, trunk and branches die, and transpiration and transport capacity decline. Due to the Chinese sweet plum's unique physiological characteristics, the growth pause caused by the death of some root, trunk and branch cells will inevitably hinder the growth of the corresponding branch sections, and over time branch dieback is unavoidable. In fact, this is also a self-regulating function of the plant: because the growth balance of the whole plant is disrupted, it will abandon some branches to maintain the balance of the whole plant's growth. This situation is also common in plant growth in nature.
3. Potted Chinese sweet plum must be repotted and soil-changed frequently.
The reason Chinese sweet plum is deeply loved by bonsai enthusiasts is that it has extremely strong sprouting ability, making the choice of branch points very convenient. We know that tree species with strong sprouting ability also have extremely developed root systems. For Chinese sweet plum under potted conditions, because its root growth space is limited, if it is not repotted for a long time, its roots will grow in a spiral along the pot wall, forming a "root nest," seriously affecting the roots' water and nutrient absorption, and thereby affecting the normal growth of the whole plant. Therefore, potted Chinese sweet plum must be repotted and soil-changed frequently. Small and medium-sized potted Chinese sweet plum must be repotted once a year; larger ones can be repotted somewhat later, but preferably once every other year. When repotting, combine it with the cultivation of multi-level roots and prune the roots appropriately. Chinese sweet plum is not very demanding about soil; it can grow normally within a pH range of 5.5 and above, but the soil must be loose and permeable.
The above are the techniques that need to be grasped with priority when growing Chinese sweet plum. Growing Chinese sweet plum requires years of effort, and it is truly a pity if a potted Chinese sweet plum work is ruined because of branch dieback. Therefore, in daily care, observe and summarize diligently to avoid branch dieback in Chinese sweet plum.