Raising orchids, like raising children, needs to be carefully cared for, and if you are not careful, the leaves that should be as green as jade may become yellow. Whenever I see those well-cared for orchids, the leaves turn from green to yellow, my heart is always mixed. However, after years of exploration and practice, I also have some experience in the causes and countermeasures of orchid yellow leaves.
First of all, the yellow leaves of orchids may be a normal metabolic phenomenon. It's like a human being, as you get older, you lose your luster. When orchid seedlings reach a certain age, the cell vitality is weakened and they cannot absorb nutrients in time, and the leaves will naturally turn yellow and dry up. Although we cannot reverse this situation, we can prepare for it in the early stages of potting, such as moisturizing and freshness, choosing suitable planting materials, and temporarily supplementing nutrients with foliar fertilizer to delay the phenomenon of weeding.
Another case of yellow leaves is that the orchid lacks nitrogen fertilizer. It's like a person who has been malnourished for a long time and has a sallow complexion. Orchid plants lack nitrogen and cannot effectively synthesize chlorophyll, and the leaves will become thin and yellow. At this time, just sprinkle some urea or high-nitrogen granular slow-release fertilizer on the wall of the pot, and then cover the soil, and after a month, the orchid leaves can gradually return to dark green.
However, sometimes the yellow leaves of orchids are not as simple as lack of fertilizer, and can also be caused by water staining the roots. Poor drainage of planting material and poor environmental ventilation may lead to water accumulation in the orchid pot, which in turn affects the respiration of the orchid root and causes yellow leaves. This yellow leaf usually starts on the outer leaf carapace and gradually spreads to the inside. Once this situation is found, the planting material should be replaced immediately and the ventilation environment should be improved to prevent the seedlings from continuing to rot.
In addition, orchids may also have yellow leaves due to potassium deficiency. When potassium is deficient, the edges of the leaves of orchids turn yellow at first, and then gradually turn brown, as if they have been burned by fire. At this time, it is necessary to replenish potassium fertilizer in time. However, it should be noted that orchids are chlorine-resistant plants, so you must read the ingredient list clearly when choosing potassium fertilizers and avoid applying potassium fertilizers containing chlorine. I generally choose a slow-release fertilizer with a high proportion of potassium in the whole coating granules, and use it with leaf spray potassium dihydrogen phosphate to supplement potassium.
Finally, there is an abnormal yellow leaf phenomenon that requires special vigilance. This kind of yellow leaves often appear in late spring and early summer, and when the new seedlings grow to a certain height, the heart leaves begin to turn yellow and are easy to pull up, and the broken mouth has a foul smell. This is soft rot, immediately pick up the planting material to check whether the reed is rotten, if there are signs of decay, immediately remove and sprinkle with fungicide. At the same time, the incision should be exposed to the air, as most germs are anaerobic, and sunlight and air can inhibit their reproduction.