Cannabis leaves turn yellow – what to do?
Cannabis leaves are the main indicator of plant health. Their color determines the lack or excess of nutrients, and an experienced grower also knows how to identify marijuana diseases by the color of the leaves. Choose 100w grow light with our help. Why do hemp leaves turn yellow? Is it necessary to immediately sound the alarm if you notice yellowness on the foliage? What to do if hemp leaves turn yellow, curl down, dry?
Why leaves turn yellow on marijuana
Before you take any action, you need to figure out why the leaves on your plants are starting to turn yellow. The most common reasons are:
- natural processes during growth;
- lack of nutrients;
- light burn of marijuana;
- chemical burn;
- cannabis parasites and diseases;
- wrong temperature regime;
- excess moisture, excessive watering;
- changing the way of growing (for example, planting plants outdoors);
- violation of indoor growing technologies (early transfer to flowering, etc.)
The color and condition of the foliage will tell you why the marijuana leaves turn yellow, and what kind of problem arose. You should also pay attention to the following point: is the problem present on all bushes or only on some? If, for example, yellowness and dryness of the tips are seen on bushes located closer to the lamp or in a sunnier place when it comes to growing outdoors, then, most likely, excess light affects. And if the same symptoms are observed in all bushes, it is imperative to examine all plants and substrate for diseases and parasites, and then be puzzled by the cannabis treatment, which will help save the bushes and preserve the harvest.
The lower leaves turn yellow
The budding cannabis grower gets scared and sounds the alarm when he sees the lower leaves of the marijuana turn yellow. It should be remembered that throughout the entire cycle, from germination to harvest, hemp leaves change color, and old foliage begins to turn yellow a little. This is a natural process, and in this case, it is okay if the leaves of marijuana turn yellow when grown. The best a grower can do is to gently remove the old yellowed leaves. They no longer participate in productivity but consume the energy that the plant receives from light, air, and nutrients. Removing old leaves promotes better growth of young foliage, better flowering, and as a result – better quality of the crop.
Another reason for the yellowing of the lower leaves is improper watering. A lack of moisture leads to drying out of plants, an excess – blocks the access of oxygen, as a result, the plant suffocates. If the marijuana leaves are drooping and curling down, you need to balance the amount of moisture.
The upper leaves turn yellow
If the top leaves of marijuana turn yellow, this is a sure sign that something is wrong with the plants. An experienced grower will identify the problem at a glance at the bushes and take the necessary steps to preserve the crop. For a beginner, the appearance of yellowness on the leaves becomes a cause for alarm, and his main task is to correctly determine the cause of what is happening. If the culprit is improperly balanced feeding, watering, or if indoor plants have been incorrectly moved to a different stage, the grower needs to re-evaluate the fertilizer balance or lighting fixtures. What exactly is the reason for the yellowing of the leaves can be determined by their appearance, shade, location of yellowness?
First, it is worth remembering that before harvesting, when the bushes are watered with clean water without feeding, a lack of nutrients, especially nitrogen, is normal. It is during this period that you should monitor the amount of water, avoid excess moisture, and do not use top dressing. What exactly is lacking in plants – the color and modifications of the leaves will tell about this.
Nitrogen deficiency: Marijuana leaves turn pale and yellowish.
Magnesium deficiency: the lower and middle leaves are covered with yellow spots with dark veins, the tips are bent upward and acquire a rusty tint.
Potassium deficiency: the edges of the leaves brighten, dark spots appear, the tips of old leaves turn brown.
Sulfur deficiency: the leaves acquire a pale green tint with a slight yellowness, the tips are bent downwards, visually resemble burnt ones, the leaf stalks turn purple.
Iron deficiency: the leaves on the tops of the bushes turn yellow, the veins take on a pronounced green tint.
Manganese deficiency: veins of young leaves turn yellow.
Zinc deficiency: the tips of the leaves burn and shrivel, the veins turn yellow.
Phosphorus deficiency: Growth is inhibited, brown spots appear on the leaves of marijuana.
The correct choice of balanced feeding is one of the keys to healthy growth and a good harvest. The offers a wide range of supplements and fertilizers for marijuana at all stages of growth. The consultants of our store will help a novice grower to choose the right fertilizer complex depending on the growing method and stage of growth.
The source of the problem associated with the yellowing of the upper leaves may not only be due to the improper use of fertilizers. Overheating, light burn, drying out are also common problems when growing in a growth box. Gaining growth, young bushes shorten the distance between the leaves and the lighting device, as a result – the plants receive light shock and burns, the marijuana leaves curl, the tips of the marijuana leaves dry and die off. This can be avoided by monitoring the growth of young bushes and changing the position of the lamp in the growth box in time.
Parasites, fungal and other diseases are also the reason why the tips of the leaves turn yellow and dry. When alarming symptoms appear, the first step is to examine all the bushes and understand whether the problem has affected the entire garden or individual plants. In the second case, the most acceptable option is to destroy the infected plants and take measures to preserve the rest of the crop. If the disease has affected all the bushes, treatment should be started. You can buy means for therapy and hemp immunity enhancement in our GrowPro online store.
The most common diseases in marijuana include mold, fungal diseases, and parasites:
1. Tobacco mosaic virus
This disease is not very common, and this is its danger. The tobacco mosaic virus, which manifests itself as brown and whitish spots on the leaves, is contagious. If this disease is found, the affected bush should be destroyed to avoid spreading the disease to healthy plants. After that, it is necessary to replace the substrate or soil, since the causative agent of the disease is transmitted through the soil.
2. Fungi and mold
If yellow or brown spots of several millimeters are found on the plants, most likely the cause is fungal diseases. The most favorable conditions for such diseases are too high humidity and too low temperature. For the prevention of fungal diseases, it is necessary to control and maintain the temperature regime and the optimal level of humidity in the grow box. If fungus or mold still affects the plants, all key indicators must be brought back to normal and the diseased bushes must be treated with fungicides.
3. Parasites and pests
This problem is most common when grown outdoors as insects and other parasites are found naturally. For infection with parasites, symptoms such as small yellow or whitish spots and stripes are characteristic. The pests themselves – aphids, mites, insects – settle on the inside of the leaf, so when growing marijuana outdoors, you should check the bushes daily for parasites and their eggs or larvae on the leaves.
In addition to such checks, the prevention of infection is the treatment of bushes with insecticides, both natural and synthetic. However, with such processing, measure and care should be taken to avoid chemical burns and other damage to leaves and bushes in general. A special top dressing for the soil is also recommended since pests can be found in the soil that eats up the root system.
If the parasites were found, complete disinfection should be carried out, up to the destruction of the eggs of the pests, and then the plants should be treated with insecticides.