molybdenum deficiency marijuana

Molybdenum Deficiency In Cannabis Plants

Molybdenum deficiency is rare. But if it hits your cannabis plants, it could be the beginning of the end. You really don’t have time to waste if your marijuana is suffering. Stricken cannabis plants need to be worked on urgently. Ignore this mineral at your peril.


Molybdenum deficiency will test the most eagle-eyed of cannabis growers. This one really is tough to diagnose correctly. Troubleshooting molybdenum deficiency will not only cost precious time, but most likely worsen the condition. Chlorosis striking the middle portion of cannabis plants foliage is commonly mistaken for nitrogen deficiency or calcium and magnesium deficiency.

In fairness, there is sound logic behind such assumptions. But don’t assume anything when it comes to unhealthy cannabis plants. Take a closer look. N deficiency tends to creep up a plant from the bottom up. Ca/Mg deficiency is rare in soil grows and more of a mid-late bloom problem in coco and hydro cultivation. Also, take note of the leaf discoloration, which will have brown crispy fringes and orange to pink shades in the centre. Eventually in a week or so, you will notice it is highly mobile as new growth begins to wither and curl.


Beginner hydroponics growers can potentially run into this problem quite easily. The lower pH range of 5.5-6.0 required for hydro cultivation can be tricky for novices using starter kits and pH pens for the first time. Dialling in pH to the optimal level for every feeding of nutrient solution takes practice to perfect. Unfortunately, hydroponics is unforgiving. Precision is a necessity. PH below 5.5 will cause a molybdenum lock-out.

Coco and soil growers are not exactly in the clear, although these cultivation styles are less prone to molybdenum deficiency. Peat and coco coir-based soil and soilless mix substrates act as a buffer for the root zone. 6.0-6.5pH is preferred. However, should the pH of nutrient solution be administered too low, too often a molybdenum deficiency can and likely will develop due to nutrient lockout.


Catch molybdenum deficiency early and it’s a simple 1-2 solution. Step one to remedy molybdenum deficiency and most cannabis ailments is a cleansing flush of the medium with pure 6.0pH water. The micronutrients the roots need are locked-out and the excess fertilisers need to be leached.

Step two is making sure the pH is perfect, per growing medium, for the follow-up feed of nutrient solution. Direct supplementation is not really an option as only trace amounts of molybdenum are required.


For whatever reason, if you are delayed treating molybdenum deficiency, expect some permanent damage to your cannabis plants. In addition to the above 1-2 solution, a third, less pleasant step is required.

Step three is pruning away the necrotic growth. If plants are still in vegetative growth, it’s not the end of the world. Top plants and remove the dead and dying leaves. 2-3 weeks recovery will be required, depending on how far chlorosis spread. On the other hand, if you must prune during bloom, make sure to remove leaf stems when pruning flowers to avoid bud mould. Yield will be reduced. But a smaller stash is better than no stash.


As is the case with the majority of micronutrient deficiencies, the best way to avoid the headaches later is to invest in high-quality substrates and nutrients in the beginning. Using cannabis-specific growing mediums and fertilisers is recommended.

Furthermore, the grower must take responsibility and ensure the root zone is healthy at all times. Careful monitoring and adjustment of pH throughout the cannabis lifecycle are essential. Get a pH pen or pH-perfect nutrients. Either way, stay in control of feeding. If you can, your marijuana will avoid molybdenum deficiency. And most other nutrient deficiencies altogether.

Easier to correct than it is to pronounce, molybdenum deficiency is a lesser known marijuana problem. This is the cannabis E.R. blog with the solutions.

Molybdenum Deficiency In Cannabis Plants How To Deal With It

Published : Oct 24, 2017
Categories : Cannabis cultivation

Molybdenum deficiency is common in many plants, and cannabis is no exception. We discuss several methods to deal with this problem to keep your plant in great shape.

Like any other plant, cannabis is a living organism that requires ample care and cultivation time. Missing out on any vital step could lead to serious nutritional deficiencies, which will harm the plant in the long run.


One common scenario would be for your bud to experience molybdenum deficiencies. In a nutshell, this problem is similar to when a plant lacks nitrogen, as it begins to experience some discolouration and physical changes. In most cases, edges of leaves turn a bright orange, pink, or red colour, eventually moving toward the centre of the leaf.

When molybdenum deficiencies happen in cannabis plants, it is mainly because of low pH levels. In a nutshell, pH is the measure of acidity or alkalinity on a 1-14 scale. For cannabis, a more acidic environment is essential for optimal growth, which is why these plants are still sometimes better off grown outdoors, or even in the wild.


Maintaining any plant’s pH level is important for its health. The likelihood of it suffering leaf problems like discolouration is lessened, and it can produce bigger yields at a quicker pace. The right pH levels help plants, cannabis in particular, gain access to available nutrients at all times. It is important, however, to find the right balance between the upper and lower pH-threshold.

The ideal pH for plants growing in soil is between 6.0-7.0, while plants grown soilless or hydroponically should be at 5.5-6.5. Going over or under these figures would physically manifest in a plant, particularly in its color, even if the right nutrients have been made available.


Once you spot some signs of molybdenum deficiencies on your plant, it is important to take action right away. The first thing to do is to flush your system with clean, pH’d water without any nutrients. This will help rid the plant of any salt present that could be hindering the roots from absorbing the molybdenum.

Even if you are growing mostly indoors, it is still beneficial to allow your plant some exposure outdoors. This will temporarily help reduce excess heat and humidity from being locked-up inside a room. Water plants regularly (but not too much), either in the early morning or evening to prevent instant evaporation from the heat of the sun.

Regarding air circulation, it would be best to set up a fan system indoors that gives your crop a consistent, gentle breeze. This will help it ingest the carbon dioxide that it needs, especially during the light hours.

Caring for a plant, especially cannabis, may entail that you spend a generous amount of time, effort, and money, but these are just the steps you need to take to enjoy the fruits of your labour later on.

If your plant is experiencing nutrient deficiencies, there are ways to quickly fix the problem. Here's how to find out if your crop has a molybdenum deficiency.