Why cannabis leaves turn yellow

Cannabis leaves are a prime indicator of a plant’s health. Only green foliage of the correct shape is capable of 100% effectively participating in the process of photosynthesis, transforming light energy into chemical energy in sufficient quantities. If the marijuana leaf starts to turn yellow, then this is the main sign that something went wrong. The problem can be eliminated only when it is possible to find out the reason for its occurrence. To do this, proceed in the following sequence.

Which cannabis leaves have turned yellow?
Hemp leaves are able to change their color over time. Older foliage first turns dark green and then brightens. Sometimes it becomes so yellowed that it closely resem

bles the symptoms of diseases. In fact, there is nothing wrong with that. Such leaves should simply be cut off. The fact is that over time they begin to consume more vital energy than they produce. Defoliation allows the plant to concentrate on the young foliage and flowers, which results in a positive effect on the yield. Most often this happens with large “fan” leaves.

Cultivation conditions
Cannabis foliage can turn yellow as a result of unfavorable cultivation conditions. This most often occurs at elevated temperatures and humidity. If the thermometer readings remained above 30 degrees for several days, then there is nothing surprising in the yellowness of the leaves, especially if the humidity was above 60%. You just need to lower the temperature to 23-27 degrees and ventilate the grow box well.

If only those leaves that are closest to the light source turn yellow, then we will talk about light or temperature stress. Either the lamp shines very brightly, or it significantly heats the air near this foliage. However, the grower needs to increase the distance from the light source to the plant.

Also, yellowing can occur due to insufficient watering of the cannabis. In this case, the problem will be systemic. Generally, all of the foliage below will look wilted. After watering, everything should go away. To prevent this from happening, you should check the degree of dryness of the soil at a depth of 3-5 cm every few days.When it becomes dry, then the plant should be watered.

Pests and diseases
If young foliage begins to turn yellow, then the problem can be classified as more serious. First of all, the grower should inspect all the plants. If the problem has arisen for all rastishki, then it is of a systemic nature. Quite often, this occurs due to the appearance of mold, fungi or insect pests. To find out exactly, you need to carefully examine the bushes with a magnifying glass.

First you need to check the underside of the yellow leaves. Ticks or larvae of other parasites can live there. You should also inspect their upper side for damage by gray mold or powdery mildew. Next, you should pay attention to the topsoil. Quite often, aphids settle in it, which causes significant damage to the roots of the plant. As a result, they become unable to absorb nutrients normally. As a result, the plant begins to lack them.

Lack of nutrients
If the foliage has turned yellow throughout the greenhouse, then the problem is systemic. Most likely, the plants are deficient in nutrients. First of all, it should be understood that the lack of micro- and macroelements can arise not only because of the grower’s stinginess for feeding, but also because of its excessive amount. This happens especially often when using inorganic fertilizers, which are salts that accumulate in the soil. As a result, the soil pH level changes, and the plant becomes unable to absorb the necessary chemical elements from it. This is called nutrient blockage. Growers encounter it much more often than conventional under-feeding.

Marijuana leaves can turn yellow due to a lack of these nutrients:

Nitrogen. Yellowness begins to appear on the leaves. If this happens on the eve of the harvest, then there is nothing wrong with that;
Potassium. The edges of the leaves begin to turn light or yellow. As the problem worsens, dark spots appear;
Magnesium. Yellow spots with dark blotches appear on the lower and middle foliage. She begins to curl up;
Sulfur. The leaves begin to turn pale, acquire a yellow tint. Their tips are curved downward;
Manganese. On young leaves, the veins turn yellow. A little later, the problem appears on older foliage;
Zinc. The tips of the foliage first turn yellow and then brown;
Iron. New leaves begin to turn yellow from the stem. Later, their tips are bent upward.

The best way to prevent all of these problems is to constantly monitor the soil pH and EC. The first should always be between 5.5 and 6.5, and the second at 0.75-2.0. Also, regular flushing of the soil will not be superfluous. It should be done no more than once a month. It will be especially useful when transferring cannabis to the flowering stage.