Zinc Deficiency In Cannabis Plants
Troubleshooting one deficiency will help deal with others when growing marijuana. This guide will show how to spot zinc deficiency as soon as possible.
Zinc is a mineral and one of many essential micronutrients necessary for a healthy plant diet. Despite cannabis requiring an astonishingly small quantity of it, it is nonetheless crucial for numerous physiological activities. Zinc is used by the cannabis plant to build proteins and macromolecular structures like membranes. It also fundamental to regulate enzyme function. Zinc is also co-factor of gene expression by stabilising both DNA and RNA structures. The growth hormone auxin requires zinc to operate.
So if you have ever had a cannabis clone that for some unknown reason was not up to par with her sisters, it could have been a zinc imbalance. Most of the time you will notice a deficiency rather than excess. While excess zinc certainly does harm the plant, it is a much rarer occurrence, and the plant can deal with this situation better.
Excess zinc will primarily lockout iron which is easier to spot. On much rarer occasions, zinc levels may become so high it becomes toxic. If this occurs, the cannabis plant will quickly die off. This last scenario is almost implausible to think of!
So we will focus on zinc deficiency. A direct zinc deficiency is not a common occurrence and usually a side effect from tertiary causes. More often than not, it is pretty straightforward to fix.
HOW TO SPOT A ZINC DEFICIENCY IN THE CANNABIS PLANT
Zinc is an immobile element. This means that once deposited it can no longer be relocated to other parts where it is needed the most. When a deficiency happens, older parts of the plant cannot distribute zinc reserves from one place to another, as it can with nitrogen or phosphorous. Therefore, early signs of zinc deficiency occur at the newest growth zones, generally at the top.
You may start noticing a plant is not growing as vigorously as it should. Internodal distance is progressively shortening. New growth shoots look a little different than earlier ones, like if they were shy to open up. Shoot tips will congregate, wrinkling up close together. Once they finally do open and start to stretch out, leaves will begin to yellow from the veins out.
From here on, if the issue is not quickly addressed the results could be very damaging. The yellowing will lead to some rust-like spotting. The tips and outer margins of the leaves will start shrivelling. Clear signs of irreversible chlorosis will be present.
By this point, the leaf is completely yellow, reddish and brown – becoming crumbly and crisp. Buds will contort, start drying up and will eventually die off. This is a doomsday scenario when no corrective measures are taken. With a little knowledge and care, it is something relatively simple to deal with.
CAUSES FOR ZINC DEFICIENCY
Unless you are growing in an entirely new or unknown type of soil, the most common cause of zinc deficiency in marijuana is water pH imbalance. As pH becomes too alkaline, the roots become incapable of absorbing this mineral trace element. Other micronutrients like manganese and copper quickly become unavailable. Nitrogen and calcium start getting affected too.
If growing organically, your pH range is much more permissible than when using chemical fertilisers. Nevertheless it very important to control – something organic growers tend to disregard.
The main disadvantage of organic growing is that correcting deficiencies can take a lot more time. So the best solution is prevention. Keep monitoring your pH! Since organic growing is so permissive regarding pH, growers tend to stop checking their primary water source. In some regions, be it municipal or well water, pH can fluctuate up to 3 to 4 points within the same year.
A sudden influx of phosphorus can also cause a zinc lockout in weed. Are you a hydroponic expert grower that cannot explain why you are getting this deficiency all of a sudden? pH meters routinely calibrated, everything seems dialled in as always? It could be as simple as you having run out of nitric acid and switched over to phosphoric acid as pH-down. In excessively hard water regions, a high limestone and chalk content is calcium and magnesium rich, making for a strong pH buffer. Your once nitric acid stable system now uses significant amounts of phosphoric acid to deal with that strong alkaline water. This type of Phosphorous is readily available for intake by the plant, potentially pushing it into a zinc deficiency.
Zinc is micronutrient of vital importance when growing Weed. It aids growth hormone auxin and DNA. Lack of this element will seriously hinder your yields
Problem: With a cannabis zinc deficiency, younger leaves start yellowing in between the veins. Leaf tips get discolored and start dying. the leaves may take on a unique banded appearance and the plant may stop growing vertically. There may be much less space between new nodes, which can cause new leaves to start bunching together. If the plant is budding, its flowers may stop growing or even start dying if the problem isn’t corrected.
Solution For Cannabis Zinc Deficiency
Note: Sometimes a cannabis zinc deficiency (like all deficiencies) can be triggered by stressful conditions and may clear up on its own after the period of stress is over. However, to minimize damage it’s important to react to any growing problem as quickly as possible, especially in the flowering stage.
1.) Adjust pH to Correct Range
The most common reason growers will see a zinc deficiency is when the pH at the roots is too high. Zinc tends to get locked at higher pH levels and is better absorbed by the plant in a more acidic root environment.
If you suspect your growing cannabis plant has a zinc deficiency due to too-high pH, flush your system with clean, pH’d water. This will remove any nutrient salts that may be affecting the uptake of zinc and help restore pH to the proper levels.
- In soil, zinc is best absorbed by the roots in the 6.0 – 6.5 pH range (although it’s generally recommended for soil growers to keep pH in the 6.0-7.0 range, zinc tends to be absorbed better on the lower side)
- In hydro, zinc is best absorbed by the roots in the 5.5 – 6.0 pH range (although it’s generally recommended for hydro growers to keep pH in the 5.5-6.5 range, zinc tends to be absorbed better on the lower side)
2.) Give the Right Nutrients
The truth is, most cannabis growers don’t need to add more zinc in response to a zinc deficiency!
In fact, most growers have actually already given plenty of zinc to their cannabis plants since it is found abundantly in most tap water. If you’re using quality soil or cannabis-friendly nutrients, you probably don’t need to worry about adding more zinc. In general, zinc deficiencies are more likely to appear when a grower is using heavily filtered or reverse osmosis (RO) water to feed plants since any zinc has been removed, but pH is a much more common reason growers see zinc deficiencies in their cannabis plants.
3.) Take Good Care of the Roots
Zinc deficiencies can show up with the plant is having root problems or if the plant is overwatered, even if the pH is right and the zinc is there. Proper watering practices help plants grow healthy and avoid a host of problems!
4.) Watch for Recovery
After going through all the above steps, watch to make sure that the zinc deficiency starts to clear up within a few days to a week or so. The damaged leaves may not recover completely, but you know you’re in the clear when you stop seeing symptoms on new leaves.
If you cannot get rid of a cannabis zinc deficiency, please consult our 7-Step Cure to 99% of Cannabis Growing Problems
- Bronze or brown patches
- Brown or slimy roots
- Brown or yellow leaf tips/edges
- Buds dying
- Buds look odd
- Bugs are visible
- Curling or clawing leaves
- Dark leaves
- Drooping plant
- Holes in leaves
- Mold or powder
- Pink or purple on leaves
- Red stems
- Shiny or smooth leaves
- Spots or markings
- Twisted growth
- Wilting leaves
- Yellow between leaf veins
- Yellow leaves
This page is part of our Plant Doctor series. You can use our tool to filter by symptom and help diagnose your plant.
Problem: A cannabis zinc deficiency causes younger leaves to start yellowing in between the veins. Leaf tips get discolored and may start dying.