Most cannabis growers know the three major nutrients that plants need to thrive, which are nitrogen, phosphorus, and potassium (NPK). However, there are more micronutrients that growers need to monitor to get the most out of their plants. Cannabis plants require a much smaller amount of micronutrients than they do NPK, but without micronutrients, the plants will not thrive.
Many high-quality cannabis growing mediums and fertilizers have the necessary micronutrients included. However, relying too heavily on these things to manage micronutrient levels makes it easy to miss a major deficiency. One of the most important micronutrients to monitor when growing cannabis is zinc.
Zinc is an essential mineral for a healthy plant. It plays a major role in chlorophyll production, protein building, enzyme regulation, and many other physiological processes vital to the health of a cannabis plant. Zinc directly supports the strength of the plant’s stalks, branches, stems, and leaves.
Excess zinc causes iron lockout, which is an easy issue to spot and fix. However, excess zinc is rare, and it is much more likely for growers to notice a deficiency.
Nutrients like phosphorus and nitrogen are called mobile elements, which means they can be moved from one part of the plant to another depending on need. However, zinc is an immobile element, so it is concentrated in a lower area of the plant before it can be distributed farther towards the top. Because of this lack of mobility, zinc deficiencies are first noticed at the top of the plant.
Several signs show growers that their blue ice autoflower or gorilla glue 4 auto cannabis plant is suffering from a zinc deficiency. Starting from the top of the plant and working down, growers should watch for:
One of the most noticeable signs of a zinc deficiency is discoloration of the leaves and stems. Leaves will yellow at the tips and edges while the center of the leaves closest to the stems will remain green. As the deficiency worsens, the entire leaf will become yellow and it will develop rust-like spots at the tips. If not addressed quickly, the health of the cannabis plant will suffer and growers will notice more severe signs of chlorosis.
Because zinc is essential in regulating the plant’s growth hormones and development, a zinc deficiency will cause significant abnormalities in its growth. At first, growers will notice that new growth has less vitality, growing thin and contorted compared to older growth. As the zinc deficiency worsens, the leaves curl and eventually die and fall off the plant.
Zinc is essential for plants to grow tall, so a zinc deficiency leads to stunted growth. At first, there will be less space between nodes. As time goes on, new growth will appear bunched together and the leaves will be tangled up. New leaves will seem reluctant to open up, and once they do, they will have the leaf discoloration described above.
When cannabis plants develop a zinc deficiency during the flowering stage, growers will notice that their buds are not getting heavier. Instead, they will remain light and airy and new bud growth will slow or stop completely. Not only will the plant’s yield be lowered significantly, but the potency will suffer as well.
The best way to avoid a zinc deficiency is to know what causes it. There are a few ways that one can develop but the most common cause is using water with the wrong pH. When using water with a high pH, the soil will get more alkaline over time, which will prevent the roots from absorbing zinc. It will also keep the
plant from absorbing manganese, copper, calcium, and nitrogen.
Another thing that causes zinc deficiency is overwatering. This is because overwatering leads to serious problems with the root system, such as root rot and a lack of access to oxygen. As roots get damaged, high-quality soil and fertilizers will not make a difference. The roots will not be able to absorb anything. Root problems may also develop as the result of an insect infestation or fungus growth and will have a similar effect on the plant’s ability to absorb zinc.
Growers with a zinc deficiency should also check the nutrient solutions they are using to fertilize their cannabis plants. Some solutions do not provide any micronutrients, and coupled with a soil that does not provide micronutrients, the plant will develop a zinc deficiency.
Zinc deficiencies can be deadly, so growers must take action quickly to correct the problem once they notice it. Even if the plant doesn’t die, prolonged deficiencies will ruin any buds that the grower harvests.
There are a few quality strategies that growers can use to fix a zinc deficiency, including:
Taking the proper precautions before a zinc deficiency develops is always preferable to correcting an existing problem. The damage a cannabis plant sustains because of a minor zinc deficiency is usually irreversible, so growers should try to prevent it rather than have to treat it later.
Growers should avoid filtering their water heavily, as this could remove some trace elements the plant needs, including zinc. Those who grow medicinal cannabis seeds hydroponically often use reverse osmosis water. If that is the case, they will need to add a Cal-Mag supplement to offset the lack of zinc in the water. Growers should always test the water’s pH before watering their plants to be sure it is not too alkaline and choose a growing medium and fertilizer that includes micronutrients.
If a zinc problem has already started, the first step to treating it is flushing the plants with neutral water. This will remove many of the nutrient salts that may prevent the plants’ root systems from absorbing vital nutrients. Growers must test their jacky girl strain or sour diesel plants’ soil, aiming to have a pH of 6.0 to 6.5 until the problem subsides. Afterward, the soil should be returned to a pH of 6.5 to 7.0.
Growers can treat a zinc deficiency with a micronutrient mix that contains manganese, iron, and zinc. This will not only address the zinc deficiency but will help the plant maintain a balance of all the micronutrients, rather than being overloaded on one. Before adding supplements, growers must understand how micronutrients react with one another. Too much of one micronutrient may cause a lockout of another one, so creating the optimal balance between them is essential to fixing the zinc deficiency without creating another.
Other micronutrient supplements that are effective in addressing a zinc deficiency are zinc oxide, zinc sulfate, and chelated zinc. Chelated zinc is a solution where the zinc ions have been attached to an organic molecule that prevents the zinc from interacting with oxygen or other ions present in the soil. This ensures the cannabis plant can absorb the zinc.
Growers must understand that a cannabis plant’s recovery from a zinc deficiency is slow. The plant will not show signs of improvement immediately and the parts of the plants that suffered the worst damage will never return to normal. Even if growers do not see the signs of improvement right away, it does not mean that their treatment is not working.
Growers should see clear signs of improvement after about one week. The condition of new growth will show whether the treatment is working. New leaves should no longer be deformed and will have returned to a normal color or have yellow spots. The cannabis plant’s growth rate should return to what it was before the zinc deficiency.
Treatment for zinc deficiency is best done during the vegetative stage. This is because the rate of growth at this time makes it easier for growers to see recovery signs. Once a cannabis plant starts to flower, new leaf growth stops, and the plant does not get much taller, making it challenging to spot zinc deficiency improvement. During the flowering stage, the most definitive sign that the zinc deficiency has resolved is that buds start to get tighter and heavier.
During the vegetative stage, if deformed growth is extensive or taking resources away from areas of the high thc or high cbd plant that will produce more, growers can cut them off. It is better for the plant to focus on perfecting healthy areas of the plant. If the plant has already entered the flowering stage, growers will need to decide if cutting off some affected buds is worth it to them. The buds may never get as dense as they would have, but they could still be potent after harvest.
Nutrient deficiencies cause a wide range of growth issues and may even result in a cannabis plant’s death. While many growers focus on the macronutrients, micronutrients like zinc are equally important to growing a healthy, high yielding marijuana plant. Growers must become familiar with the signs of a zinc deficiency, how to prevent it, and what to do if their plants have it. If you are a new grower, start with one of our easy to grow marijuana strains that have a little more room for flexibility when it comes to balancing nutrient levels.