Over-fertilizing harms crops instead; a brief discussion on scientific fertilizing

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Many orchid growers always attach great importance to fertilizing, thinking about fertilizing their orchids almost every day. In fact, fertilizing must be done with restraint; without rationalized fertilizing, it will only bring harm to orchids and cause the consequence of pulling up seedlings to help them grow.

Orchids are not plants that love fertilizer; their fertilizer needs are limited. Moreover, orchids also need certain conditions to absorb fertilizer, and they cannot absorb fertilizer at just any time. Let me talk about several necessary conditions for fertilizing in my personal view:

1. Suitable temperature: In general, the relatively accepted temperature is that absorption can begin only above 15°C, and the range of 15-25°C is the best time for fertilizing. In actual practice, I personally feel that fertilizing should begin when the temperature stabilizes at 15°C, while the true peak of fertilizer absorption should be between 20-30°C. Within this temperature range, orchids grow fastest and absorb more fertilizer. Above this temperature, too much fertilizing can easily cause excessive vegetative growth. When fertilizing below 15°C, the orchid root system is simply soaked in fertilizer water, absorbing very little, with a hundred harms and not a single benefit; the commonly seen situation is that the crystal tips turn black and rot;

2. Sufficient light: Without light, photosynthesis cannot occur; with insufficient light, photosynthesis is also weak. Under such conditions, absorption is slow, and the absorbed fertilizer cannot be transformed, just like indigestion in humans. Therefore, fertilizing also needs the cooperation of light. During the plum rain season, if you blindly fertilize, stem rot and soft rot follow one after another. This is also the consequence of blindly applying fertilizer. Take this year in our area, with more than a month of continuous rainy weather and very little sunlight; the examples of many growers suffering losses to varying degrees because of this can illustrate the point. The reason is that we habitually use slow-release fertilizer here, and during the plum rain season there is plenty of moisture and the temperature is also suitable for the release of slow-release fertilizer, but because there is no sunlight, the fertilizer cannot be absorbed, thus causing such consequences. Therefore, during the plum rain season, when there is sunlight, it is best to apply quick-acting water-soluble fertilizer;

3. Strong seedlings: In the past, orchid growers proposed: fertilized orchids should not remain thin for long, and thin orchids should not be fertilized suddenly. This means that for strong seedlings, fertilizing should keep up, while for thin and weak orchid seedlings, fertilizing should be light, that is, apply thin fertilizer frequently and proceed step by step slowly;

4. Complete root system: For orchids that have just been potted, rushing to fertilize is very unfavorable to orchid growth. Because orchids that have just been potted have root systems that have not yet fully recovered; fertilizing at this time, the old root tips cannot absorb, and the new root tips have not yet grown, so the harm is not shallow. Books in the past often emphasized starting fertilizing only after three months; although somewhat conservative, it is not without reason. According to observation, under very suitable conditions, new roots grow well in at least 20 days. But in reality, how many hobbyists' cultivation conditions can reach that kind of condition? Of course, under the currently popular soilless cultivation conditions, appropriately applying a little Magamp at repotting can still be effective;

5. Sufficient water supply: The absorption of fertilizer needs the assistance of water to be completed. Without sufficient water supply, after fertilizing, the water evaporates, the fertilizer concentration increases, and root burn is unavoidable.

The above points do not include foliar feeding. I think foliar feeding is only suitable for old, weak seedlings with poor root systems, just like giving a person an IV drip to supplement nutrition. Strong plants do not need foliar feeding; excessive foliar feeding will cause root degradation. Moreover, if the concentration of foliar feeding is not well controlled, it can easily cause fertilizer burn to new shoots, leaving irreversible, permanent white fertilizer burn scars.

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