How should boxwood bonsai be fertilized when it has just started to bud?
Boxwood bonsai is rather afraid of direct strong light, so during cultivation it only needs to be provided with scattered light to meet its growth needs. For newly transplanted and potted boxwood collected-from-the-wild stump bonsai, it usually needs to be kept in shade for a period of time until it successfully establishes in the pot, after which it can be shifted to the normal care and management routine. To encourage boxwood bonsai to bud, it is usually necessary to apply some fertilizer so that its leaves grow more tender green and glossy, thereby improving the ornamental effect of the foliage. So, how should a boxwood bonsai that has just started to bud be fertilized?
For boxwood bonsai, nitrogen fertilizer is usually applied, with urea diluted at 2000 times and sprayed onto the tree, achieving the purpose of topdressing through foliar feeding. Moreover, spraying dilute foliar fertilizer on boxwood bonsai can be done all year round. At the same time, combined with regular watering, a trace amount of nitrogen can be taken in. Topdressing for boxwood bonsai is often mainly nitrogen fertilizer, with the focus on keeping the bonsai green all year round and maintaining luxuriant branches and leaves, but phosphorus and potassium fertilizers must not be taken in.
Applying foliar fertilizer is the main form of foliar feeding, and foliar feeding generally uses quick-acting nitrogen fertilizer, which often achieves growth effects that soil fertilization cannot. For stump bonsai like boxwood, foliar feeding can quickly and promptly supplement the nutrients the tree needs for growth, while effectively promoting photosynthesis, making up for the phenomenon of insufficient stored nutrients from soil topdressing, thereby increasing the survival rate of collected-from-the-wild stumps and promoting their rapid growth.
And everyone knows that the nitrogen element is where cell protoplasm is formed, and it is an indispensable important “life element” in the process of metabolism. Boxwood bonsai is mainly grown for its foliage and has extremely low demand for phosphorus and potassium fertilizers, so it is not suitable to deliberately supplement phosphorus and potassium elements; usually it is enough to appropriately supplement nitrogen fertilizer. Moreover, the potassium element often exists in the tree body in ionic form and does not actively participate in the formation of important organic substances, so it often only plays a relatively large role in the reproductive growth of tree species that flower and bear fruit.
As for the fertilization issue during the budding period of boxwood bonsai, even if phosphorus and potassium fertilizers are applied, they often cannot play a role in supplementing nutrients and promoting growth; instead, they may cause unnecessary side effects. Taking the potassium element as an example, this is mainly because as potassium fertilizer is applied, potassium ions increase, and the concentration in the guard cell sap of the stomata instantly rises, causing the stomata to enlarge, so water in the tree body is easily lost. Moreover, the excessive accumulation of potassium ions also requires corresponding energy to supply, which then aggravates the overall excessive consumption of the nutrients originally accumulated by the boxwood bonsai, and this is very unfavorable for both the survival and growth of boxwood collected-from-the-wild stumps.
On the other hand, if too much potassium fertilizer is applied to boxwood bonsai, it easily causes leaves to turn yellow and drop; when the concentration is too high or the amount used is too large, it may also cause the plant to experience difficulty in breathing, ultimately leading to the plant's death due to breathing difficulty. Applying potassium fertilizer to boxwood bonsai brings such consequences, and applying phosphorus fertilizer also produces similar situations. Therefore, the cultivation of boxwood bonsai is not suitable for deliberately applying phosphorus and potassium fertilizers.