How to fertilize bonsai and flowering plants, and what to do about over-fertilization?

  Fertilization should mainly be based on the ecological conditions and biological characteristics of the plants, paying attention to the relative balance of the three major nutrient elements, as well as factors such as soil composition and the characteristics of the fertilizer to decide which fertilizer to use.

  1. Choose fertilizer based on its characteristics:

  Fertilizers are divided into organic fertilizers and inorganic fertilizers. Organic fertilizers refer to biological materials such as human and animal manure and urine, animal hair, scales, bones, and residues of grain and oil seeds, which are fermented and diluted before use. They contain comprehensive nutrients, can meet the various needs of plant growth, have long-lasting effects, few side effects, and are not prone to compacting the soil. However, they also have disadvantages such as long fermentation time and unpleasant odors.

  Commonly used inorganic fertilizers include compound fertilizers, superphosphate, calcium magnesium phosphate, ammonium nitrate, potassium dihydrogen phosphate, etc. They contain relatively simple nutrients and have the characteristics of fast effectiveness and acidifying the soil, but excessive or one-sided application can make the soil too acidic and cause soil compaction. Improper application can easily lead to fertilizer damage. Applying nitrogen fertilizer together with phosphorus fertilizer can improve fertilizer efficiency. Ammonium chloride should not be used in alkaline soil, while sodium nitrate and calcium nitrate are suitable for acidic soil. Urea is a neutral fertilizer with a high nitrogen content and is suitable for foliar topdressing.

  2. Choose fertilizer based on the type of flowering plant:

  Different types of flowering plants have different needs for nutrient elements. For foliage plants, the emphasis can be on applying nitrogen fertilizer; for plants grown for large flowers, an appropriate amount of complete fertilizer should be applied during the flowering period to ensure abundant blooming and beautiful, vivid flowers; for fruit-bearing ornamental plants, fertilizer and water should be properly controlled during the flowering period, and sufficient complete fertilizer should be applied during the fruiting period to achieve the expected results. For bulbous flowers, apply more potassium fertilizer to help the bulbs become plump; for fragrant flowers, apply more phosphorus and potassium fertilizer once they enter the flowering period to promote a strong floral fragrance.

  3. Fertilize according to the growth stage:

  Post-bloom supplementary fertilizer: do not fertilize during flowering, to avoid prematurely inducing new buds and shortening the flowering period. After the plant blooms, the organic matter in the plant has been heavily consumed and needs to be replenished with compound fertilizer.

  Bud-promoting and flower-promoting fertilizer: apply 10 days before the plant's flower bud differentiation. Mainly choose phosphorus fertilizer that can shorten the time of flower bud differentiation and promote flower bud differentiation; a 1~2% superphosphate extract can be sprayed on the branches and leaves.

  Wintering fertilizer: apply half a month before frost. In the north, carry it out between "White Dew" and "Autumn Equinox." In the south, apply it around "Start of Winter," mainly choosing potassium fertilizer that can improve the plant's cold resistance.

  4. Fertilize according to growth condition:

  If the plant is short and weak, has few branches, pale yellow leaves, small and dull flowers, a decreased seed-setting rate, and low yield, then it indicates a nitrogen deficiency.

  If the plant grows slowly, has curled leaves, is short in stature, has few flowers, and has an underdeveloped root system, then it is caused by phosphorus deficiency.

  If the leaf edges and leaf tips turn yellow and then brown and fall off, the stems are soft and easy to bend, and the ability to resist drought and cold is very weak, that is caused by potassium deficiency.

  In short, fertilization should pay attention to the relative balance of the three major elements (nitrogen, phosphorus, and potassium), the combined use of organic and inorganic fertilizers, and should be done in a timely manner, in appropriate amounts, at low concentration, and frequently.

  [Correct Fertilization Methods]

  Rather than trying to rescue plants after fertilizer damage occurs, it is better to learn the correct fertilization methods.

  Fertilization should follow "seven parts water, three parts fertilizer," especially when using compound fertilizer, the concentration should be 0.1%~0.3%, then spray it onto the potting soil with a spray bottle, not spraying too much; it is best if the solution flows out from the drainage hole.

  Solid fertilizer should be used in appropriate amounts according to the size of the plant and the size of the flower pot. For stick-shaped special compound fertilizer, generally bury 1~2 pieces in a flower pot with a diameter of about 10 cm, and bury 3~4 pieces in a flower pot with a diameter greater than 12 cm.

  The concentration of topdressing should be low. For example, the spray concentration of urea should be lower than 0.1%, the concentration of superphosphate should be 0.1%~0.3%, the spray concentration of ferrous sulfate should be 0.2%~0.5%, and the concentration of micronutrient fertilizer should be 0.1%~0.2%. For bulbous and fleshy-stemmed flowering plants, and shade-loving foliage plants, use less fertilizer; the amount of fertilizer for succulent plants should be less than that for shade-loving foliage plants; for fibrous-rooted flowering plants, each topdressing amount should be 20%~25% of the normal amount; fruit-bearing and flowering types should be given more fertilizer.

  Because of insufficient experience, many people growing bonsai and flowering plants apply too much fertilizer, causing the plants to suffer fertilizer damage. When plants suffer fertilizer damage, the main symptoms are as follows: the branches and leaves above ground quickly wilt and the leaf color becomes dull, while the underground root system changes color and rots. So once a potted plant suffers fertilizer damage, what should be done?

  [Remedial Measures]

  1. Wash the roots and repot

  Immediately remove the affected bonsai or flowering plant from its pot, wash the roots clean, cut off the damaged part of the root system, and cut off the severely wilted branches and leaves. Then replace the growing medium, repot it, water thoroughly, and place it in a shady area, avoiding direct sunlight. Spray water on the branches and leaves 3-5 times a day to ensure a balance of moisture above and below ground, until the flowering plant or bonsai returns to normal growth.

  2. Water thoroughly

  For some valuable flowering plants or those with delicate roots, it is not suitable to wash the roots and change the soil. Instead, immediately water the affected plant thoroughly 2~3 times in a row to flush out the high-concentration fertilizer.

  3. Rinse

  Place the flower pot in flowing clean water and rinse for 1~2 hours, with the water surface 2~3 cm higher than the pot rim, so as to quickly reduce the fertilizer content in the potting soil.