What to Do When Bowl Lotus Leaves Turn Yellow and Black, and How to Fertilize Bowl Lotus
Bowl lotus is a warmth-loving plant that grows best and blooms most in a warm environment with ample light. Bowl lotus has high ornamental value, which is why it attracts so many people to grow it. However, during cultivation, some people fail to master the right growing techniques, resulting in yellowing leaves. In fact, there are ways to solve this problem.
What to Do When Bowl Lotus Leaves Turn Yellow and Black
1. Repot and change the soil. If too much fertilizer has been applied, change the water immediately. Be careful not to change all of it at once; change half each time to simply reduce the concentration of fertilizer in the water. When changing the water, do not let the temperature difference be too great, so as not to alter the pH and affect water absorption by the leaves. In addition, if too much fertilizer has been applied, you can also repot and change the soil. If the leaves have turned black due to dirty water quality, it is recommended to directly repot and change the soil rather than just changing the water; otherwise, changes in water temperature and pH will worsen the condition. The correct approach is to wait until the water has evaporated and decreased, then add water of the same temperature. Note that bowl lotus must never lack water during the growing season, otherwise the leaf edges will easily scorch.
2. Outdoor care. Except in winter, keep it outdoors during the day as much as possible and give it plenty of sun, but avoid direct strong light. Pruning and cleaning: bowl lotus leaves are highly prone to disease during the growing period, so remove bad leaves promptly and disinfect with carbendazim; you can also spray with appropriately diluted pesticide. Rotting lotus seeds can also burn the seedlings and cause leaves to turn black, so you can pull out those rotting, diseased lotus seeds.
How to Fertilize Bowl Lotus
1. Base fertilizer. Base fertilizer is a certain amount of fertilizer applied when the plant is planted. However, because bowl lotus is intolerant of fertilizer in the early stage of growth, excess nutrients may kill it, so when planting you can either skip base fertilizer or apply a small amount of decomposed liquid fertilizer as bottom fertilizer, being careful not to cause fertilizer burn.
2. Top dressing. In fact, the most important fertilization task for bowl lotus is top dressing. When bowl lotus gradually establishes itself and begins to grow normally, the substrate in the soil has already been mostly used up. Bowl lotus needs top dressing to ensure normal growth; otherwise the leaves will age and flowering will be affected. When applying top dressing, you can insert a small piece of raw soybean cake into the mud of the bowl lotus and let it slowly ferment so the lotus root can gradually absorb nutrients; you can also use decomposed soybean cake or manure as top dressing.
What to Do If Bowl Lotus Rots
1. Select disease-resistant varieties according to local conditions, and be sure the seeds are pure. Loosen the soil in time to increase soil permeability, and sprinkle some lime appropriately.
2. Before planting, treat the seed lotus roots by spraying with carbendazim or thiophanate-methyl solution, then wrap them in plastic film and seal for 24 hours; take them out, let them dry, and then transplant.
3. Fertilize promptly and in appropriate amounts, mixing organic fertilizer and chemical fertilizer. At different stages of lotus root growth, control the water level well, keeping it at a suitable depth with moderate water temperature.
How to Prevent and Control Pests on Bowl Lotus
1. Noctuid moths. During the larval stage, use a combination of hand-picking and contact insecticides. Mix trichlorfon crystals with dichlorvos and add water at 1600 to 2000 times dilution for spraying; contact killing and fumigation work together with good results. Noctuid adults hide by day and come out at night, and have strong phototaxis. At night, use electric shock-type black light traps to kill them; place a basin of water with kerosene added underneath the lamp. The effective radius can reach 50 m, and each lamp can trap and kill hundreds of noctuid and similar pests per night, with very good results.
2. Aquatic pests. In summer, small red worms, aquatic earthworms and the like easily breed in the water of the pot, harming the floating leaves and root system of the lotus. For a household pot lotus, adding half a tablet of trichlorfon per pot is enough to eliminate them. For potted lotus gardens, combine this with fertilization by mixing 3% carbofuran with granular fertilizer and applying it into the pot to achieve control.
The causes of yellowing bowl lotus leaves are generally related to soil, water, temperature and other aspects, so when this happens you should find the cause at its root and then thoroughly solve it. Bowl lotus is also very susceptible to pest attacks, so pest prevention and control are also very important.