One, the soil moisture is too much or too dry
Gardenia needs enough water, but the soil should not be too wet, which will turn its leaves yellow and present yellow-green veins of old leaves. While applying compound fertilizer to improve the growth substrate, move the potted plants to a ventilated place to dry, loosen the soil and then water them, and master the watering times. Then it is necessary to ensure the good drainage performance of the flowerpot and the air permeability of the soil. If you are not satisfied with the existing basin soil, you should consider changing the basin soil.
Second, the soil is too dry.
It may also be because the soil is too dry, especially in winter in the north. The measure is to replace the potted plants with a large tray, add water to the tray to make the soil absorb water, and put it on the north-facing windowsill with scattered light to wait for the plants to recover. If the old leaves turn yellow and dry, the reason may be that the air is dry, so it is necessary to increase the air humidity, or spray it around or spread wet towels on the ground.
Third, the soil alkalinity is too high
If it is not caused by soil moisture, we should consider whether it is because the soil alkalinity is too high. The best soil for planting potted gardenias is porous, well drained and fertile. Gardenia likes acidic soil and requires a PH of 5.0 to 6.5. If the soil pH is not suitable, plants can easily and effectively absorb the required soil chemical elements, such as iron, nitrogen, magnesium and zinc. Lack of mineral elements such as magnesium and iron will lead to yellowing of plants and leaves.
When magnesium is deficient, the leaf base and tip are still green, and the leaf base may turn dark green. A certain dose of phosphate can be used, such as 1% magnesium sulfate diluent.
Without iron, the base and veins of leaves are still green. When the weather gets cold, it is more difficult for plants to absorb soil nutrients, which is easy to cause yellowing. Usually, it should be treated in spring, and a sulfur-free diluent, such as 0.2% black alum water, can be used to reduce soil alkalinity.
Fourth, plants are not adapted.
If the leaves of plants turn yellow first and then burn in the pot irrigation stage. It is necessary to move to a place where there is no direct sunlight to slow down the seedlings, ensure that the soil moisture and air humidity are appropriate, avoid fertilization and ferrous sulfate, and do not remove yellow leaves.
Verb (abbreviation of verb) is not well maintained or properly maintained.
1. Fertilization
The short-term solution to plant yellowing is to directly supplement the lack of elements in the soil, but it is only temporarily effective and needs regular quantitative fertilization for a long time. Fertilization should be applied directly to the soil, far from the roots of plants. Reducing the direct contact between roots and fertilizers and avoiding fertilizer damage is another way to reduce yellow leaves.
2. Temperature
The optimum growth temperature of Gardenia jasminoides Ellis is 16 ~ 18℃, and it needs 5 ~ 10℃ for overwintering. When the temperature is lower than-10℃, it is easy to be frozen and the leaves turn yellow.
lamplight
Gardenia is afraid of the sun, and it is best to receive 60% full sunshine every day. The environment with insufficient light hindered its photosynthesis.
4. Pests and diseases
The leaves of plants suffering from chlorosis and leaf spot disease will gradually turn yellow and wither, and pests will also endanger the health of plants, and the leaves will become wilted and the diseased leaves will turn yellow. These pests include moths, scale insects and whiteflies. When pests and diseases are found, they must be prevented in time, and attention should be paid to prevention, strengthening maintenance and improving plant disease resistance.