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Nutrient Deficiencies In Marijuana Plants

Nutrient Deficiencies In Marijuana Plants

Nutrient deficiencies or disorders in your marijuana plants can occur with every growing technique and in every growing medium; rock wool, soilless, aeroponic and hydroponic or soil.

Indoor marijuana growers usually have more problems with nutrient disorders than outdoor marijuana growers. A nutrient deficiency always slows the growth of the cannabis plants down.

The nutrients deficiencies can be caused by many things but the biggest factor is pH value.  Nutrient disorders sicken the marijuana plant and a disproportionate amount of nutrients can cause toxicity or nutrient burn. It can also cause the lock-out of other important minerals. In this Marijuana Nutrient Mini Guide you will learn everything there is to know about marijuana nutrients:

What are nutrients

Nutrient deficiencies cannabis

Within the world of cannabis cultivation, nutrients issues are a constant concern. The macro nutrients are the usual offenders: potassium (K), phosphorus (P) and nitrogen (N). You can also end up with calcium, zinc, or magnesium imbalances, although these are usually slightly less common.

Usually, the nutrient deficiencies experienced in cannabis cultivation show symptoms in the pH of the water and soil around the plant. A balanced pH is one of the ways you can ensure that your plants absorb all of the nutrients they need.

Adjusting the pH is simple: all you have to do is make the environment (whether soil or water) more alkaline or acidic, depending on its current level. The pH for cannabis should be somewhere near the neutral middle of the pH scale, somewhere around 6 or 7. Each of the different nutrients that you add or take away from the environment will affect the pH and the general absorption of nutrients by your plant. Understanding this relationship will help you grow the healthiest plants.

Correct PH levels

Ph levels nutrient deficieny cannabis

The pH scale is how growers measure the acidity or alkalinity of the soil and water around their plant. The scale ranges from 1 to 14, with 7 being neutral pH. 1 is the most acidic while 14 is the most basic (alkaline). When you are watering your plants, you want to be absolutely sure that the pH levels are appropriate, otherwise the plants can be damaged and their health can deteriorate.

Although hydroponics systems can sometimes support a cannabis plant with a pH of as low as 5.5, the ideal range is somewhere around 6. Read more about ph levels

Testing pH levels is extremely easy. All you need to do is purchase test strips from a local gardening supply shop or a ph meter. This will help you avoid over or underfeeding your plants. At the same location you pick up test strips, you should be able to purchase commercial mixes of soil that easily let you modify and stabilize the pH of your own soil. Ph strips and meters are also online available at this link.


Boron deficiency cannabis

One of the rarer deficiencies is boron. It’s not common for cannabis cultivation, but it can certainly damage the plant’s potential growth. The most visible signs of boron deficiency are when the growing tips of the plant begin to turn brown or gray.

The growth itself will slow significantly or stop if there isn’t enough boron. In addition to the damage experienced by the growing tips, the leaves may start develop dead spots. They will be small and scattered, and might go easily unnoticed.

Make sure you take counteractive measures to fix boron deficiencies right away. Fixing the problem usually starts with adjusting irrigation processes, and making sure you’re getting the boron back into the environment. Boric acid is a simple and common choice for growers, but compost and natural mixes are also potential options to bring the levels back to normal. Read more about boron deficiencies in marijuana plants.


Calcium deficieny cannabis

Calcium deficiencies are relatively uncommon for outdoor growers but are not uncommon for indoor growing and users of hydroponics systems. Some areas also have water supplies which don’t contain calcium, and if growers don’t add calcium to their irrigation reservoirs, there likely won’t be enough for the plants to thrive.

Additionally, if you’re growing in a hydroponics system and you’re only using water and nutrients in a solution, then you might be missing a good source of calcium. Calcium deficiencies will usually display symptoms of big dead patches on unusually dark leaves.

The symptoms of calcium deficiencies will usually first arise in the older growth. Branches may become weakened significantly, and any additional weight or stress could cause them to crack or break off. If you don’t address a calcium deficiency early, the plant may also develop some issues in the root systems. Thankfully, treating a calcium deficiency is usually a pretty simple process. Growers often use lime, applying it to the soil or substrate and letting the plant take it from there. Read more about calcium deficiencies in marijuana plants.


Copper deficiency cannabis

Copper deficiencies in cannabis plants are relatively uncommon, but they can cause a lot of damage to new growth. The initial symptoms will be a necrosis of the plant matter in new leaves. This will cause the leaves to look brownish or blue-gray at the tips. The new leaves, flowers and other new growth on the plant can also come in limp and weak if there isn’t enough copper.

Since copper is easily renewed in the plants environment, and very important for letting the plant thrive and mature, you need to make sure you do your part. There are a number of fungicides which contain copper, but there are other options, too. We’ll cover more of your copper options farther along. Read more about copper deficiencies in marijuana plants.


Iron deficiency cannabis

Iron deficiencies are not uncommon for cannabis plants. The first area growers will see evidence of an iron deficiency will be in the new growth of the plant, especially the leaves. The upper leaves will usually be the most affected, becoming discolored and yellowing distinctively.

The veins of the leaf will remain green, but the leaf itself just won’t have enough chlorophyll if the plant has an iron deficiency. Iron holds a vital role in the production of chlorophyll in cannabis plants.

Beware: an iron deficiency and a magnesium deficiency can look very similar to one another. The main difference is that an iron deficiency will primarily affect new growth on the plant. That means the top leaves will be affected far more than those at the bottom and middle of the plant.

Iron deficiencies often occur at the same time as improper pH levels, so you’ll need to take that into account. It’s also common for iron deficiencies to occur in conjunction with manganese and zinc deficiencies, so keep an eye out for those. Read how to treat iron deficiencies in marijuana plants.


Magnesium deficiency cannabis

Magnesium deficiencies are another relatively rare occurrence for outdoor growers of cannabis, but it’s found indoors and with hydroponics systems. Usually, it will affect the lowest leaves of the plant at the beginning, causing them to yellow and weaken.

Left unchecked, the leaves will die. This deficiency can also work its way up the plant from bottom to top until it reaches the crown. Magnesium is a very important element for the development of chlorophyll in the cannabis plant, so don’t let the problem worsen, especially in the early stages of growth.

The easiest and most common way to fix a magnesium deficiency is the application of Epsom salts. Be careful, though, you want to make sure you’ve diagnosed the deficiency correctly before trying to fix it. If you apply too many unneeded nutrients, you could be causing a whole new problem instead of fixing the real issue. Read more about magnesium deficiencies in marijuana plants.


Manganese deficiency cannabis

Manganese deficiencies are also fairly uncommon in cannabis cultivation. You’ll usually find them occurring in tandem with zinc and iron deficiencies, so remember to carefully test and analyze your plant’s environment when treating them.

A manganese deficiency will display symptoms in new growth, primarily in the leaves. The leaves will develop dead spots and begin to yellow. On the other hand, too much manganese can inhibit nutrient absorption and cause iron deficiencies.

Manganese is a very important element for the creation of chlorophyll and also for the production of nitrates. Make sure you have plenty of manganese in your nutrient solution or plant substrate. Getting manganese in a water-soluble form is always a good idea, since it simplifies the application process. Many growers also prefer compost or greensand. Read more about manganese deficiencies in marijuana plants.


Molybdenum deficiency cannabis

Molybdenum deficiencies are very uncommon, but if they do occur, they will cause some unpredictable and negative effects on your cannabis plant. Without enough molybdenum, the plant’s middle leaves will begin to yellow, and any new foliage will grow out warped or stop growing entirely.

The shoots will begin to curl, and the leaves can develop a strange crimson hue at the tips. Molybdenum aids primarily in the development and production of ammonia for the plant.

One of the main reasons molybdenum deficiencies are so uncommon in cannabis plants is the tiny amount required. Plants don’t require very much molybdenum. That also means that you should show restraint when treating a molybdenum deficiency. Growers often favor sprays and infused solutions to treat the plant. Read more about molybdenum deficiencies in marijuana plants.


Nitrogen deficiency cannabis

Nitrogen is one of the most important nutrients for healthy plant growth, and because it’s so heavily used by cannabis, it’s not uncommon for plants to develop nitrogen deficiencies. Nitrogen is used for a wide variety of plant processes, from photosynthesis to the production of vital amino acids.

Symptoms of a nitrogen deficiency are yellowing leaves. If the deficiency is left unchecked, the yellowing leaves can wither and die. Nitrogen deficiencies will usually begin in the bottom leaves of the plant and then spread up to the top.

The best way to treat a nitrogen deficiency is to make sure that you’re using a fertilizer which contains the right ratio of macro nutrients: nitrogen, phosphorus, and potassium. Plants require extra nitrogen during the vegetative stage of growth, so make sure they are getting enough! If you need a quick nitrogen boost and don’t have time to worry about long-term fixes, you can use bat guano or compost to help improve the plant's health. Read more about nitrogen deficiencies in marijuana plants.


Phosphorus deficiency cannabis

While not as common as nitrogen deficiencies, phosphorus deficiencies are a definite possibility, especially in hydroponics systems. The initial symptoms of a phosphorus deficiency are darkening foliage and slowing growth. The leaves will begin to curve and curl and develop a brown hue.

Other plant parts like petioles will also darken, possibly becoming more blue or red. Phosphorus is most important during the flowering phase of growth, but it also adds structural strength to the roots and stems of the plant. If your plant lacks phosphorus during the flowering phase, you will limit the potential yield.

To take care of phosphorus deficiencies, try to use a fertilizer which contains a higher ratio of phosphorus than whatever you were using before. Fertilizers specifically developed for the flowering phase work well, as does bat guano. Water-soluble fertilizers will be your best option for maximum efficiency and ease of use. Read more about phosphorus deficiencies in marijuana plants.


Potassium deficiency cannabis

Potassium deficiencies are fairly common in the world of cannabis cultivation. This is because, with most fertilizers, potassium occurs in the lowest ratios. Compared to the other macronutrients, less potassium is required by the plant.

A potassium deficiency has unusual symptoms: the plant might actually grow taller more quickly and look healthy at first, but keep an eye on the lower foliage. If the plant doesn’t have enough potassium, the leaves can turn brown and begin to die.

You also might notice areas where growth slows or becomes irregular. Remember that potassium is very important to the transfer of water and other nutrients throughout the plant. This means that if you have a large deficiency, it can affect the health of the whole plant. To treat your potassium deficiencies, try adjusting the fertilizer mix you are using or add a water-soluble potassium additive. Read more about potassium deficiencies in marijuana plants.


Silicon deficiency cannabis

Silicon deficiencies almost never occur in outdoor growing but are always possible in controlled indoor environments. Silicon itself is usually highly abundant in nature, as well as being well represented in fertilizers and nutrient solutions.

Silicon is very important for plant production in general, and so a deficiency will cause the branches and stems of your plant to become weaker than they should be, and the photosynthesis process may be inhibited. Silicon also deters insects and pests; you might notice that you have more issues with insects if your plant has a silicon deficiency.

In order to treat a silicon deficiency, growers have a number of different options. Many growers favor diatomaceous earth or liquid silicon. Just remember that silicon deficiencies are fairly rare, and it’s always a good idea to check other causes before trying to add more silicon. Read more about silicon deficiencies in marijuana plants.


Sulfur deficiency cannabis

Sulfur deficiencies don’t occur too often since most fertilizers will have the requisite amount of sulfur already present. Symptoms of a deficiency include yellowing of new and developing foliage, as well as stunted growth.

The new leaves may also be narrower and more brittle than they should be. Sulfur plays an important role in a number of different vital processes, including chlorophyll development and root system growth.

If your plants do develop sulfur deficiencies, they can be easily treated with the application of potassium sulfate or Epsom salts. Read more about sulfur deficiencies in marijuana plants.


Zinc deficiency cannabis

Despite the moderately small amount of zinc required in the cannabis plant, zinc deficiencies occur fairly regularly. Symptoms of a zinc deficiency include twisted foliage growth and yellowing of the veins of the older leaves.

It’s also possible for the plant to begin to lose color and grow paler. When the flowering phase occurs, the same issue can crop up in the buds, and they might curl or become deformed. Zinc deficiencies often occur in tandem with iron or manganese deficiencies.

Zinc plays an important role in a number of different plant processes, including plant development and the production of vital enzymes. Severe deficiencies can cause the plant to wilt or even break the stem. Because of the linkage between zinc, manganese, and iron, it’s important to be careful when trying to treat a zinc deficiency. Read more about zinc deficiencies in marijuana plants.

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Comment Section

60 thoughts on “Nutrient Deficiencies In Marijuana Plants

By robert morgan on 18 April 2015

I have your grow bible but I don't have the plant care book can you help. thanks I love your site

By isotonix on 22 April 2015

It's appropriate tjme to make some plans for the long run and it
is time to be happy. I havve read this put up and if I may just
I want to recommend you few attention-grabbing issuss or
advice. Perhaps you could write next articles regarding this article.

I wish to read even more issues approximately it!

By Mike on 29 April 2015

Finally a website with related pictures for growers. I was able to pin point exactly my issue and ways to help fix the issue. Thanks

By mike on 30 April 2015

I have a huge problem as soon as I'm in flowering my leaves start to get brown spotting or necrosis spots then they turn brown with the fan leaves curling up then some twist til the infected leaves becomes brittle and die and it seems to start with 1 or 2 plants then moves to all of them. My room temp. Never over 80 and humidity never over 50 please help

By CuriousJane on 29 September 2016

How did u get this resolved?

By Ben frank on 8 December 2017

By mike April 30 2015 did you ever figure out what was going on?

By k ride Kush on 7 February 2018

Do you hand water? check run-off, you probably have high PPM or PH with salt build up. Water more often until 15% run-off if in Rockwool. Had deficiency in RW all the time when I hand watered.

By Dane Bowen on 18 May 2015

I think you made a mistake in " The best pH levels for marijuana plants". You say "The scale ranges from 1 to 14, with 7 being neutral pH. 14 is the most acidic while 1 is the most basic (alkaline)." Isn't 14 the most basic and 1 the most acidic? I am a newbe and this comment has confused me to no end.

By Jennifer ILGM on 20 May 2015

Dane thanks for noticing, you are right. I will correct it right away!

By Elisabeth on 20 January 2017

Seriously ! Reading and depending on this article and the one of most important pieces of information is incorrect . Correct the mistakes already it's 2017 .

By Roy ILGM on 23 January 2017

Hi Elisabeth, this was rectified in 2015 🙂

By sean on 18 May 2017

Calm down and smoke a joint!

By Pnizzle on 28 October 2017

Who cares what more acidic or not. Ph is 5.8-6.3. Period

By Andrew McDonnell on 13 May 2016

Its worth noting the scale is logarithmic, this means 7 is 10 X more alkaline that 6

By versant on 31 July 2018

think you got that backwards...0 is most acidic 14 most alkaline

By Jeff Phinney on 5 September 2015

I cannot find feeding schedule for the three bottles of of nutrients,grow ,flower, and mass.All other information that I have read is great. Please send feeding schedule Thanks, Jeff

By Jennifer ILGM on 7 September 2015

Hi Jeff, please mail our customer service at [email protected], they will make sure you get it.

By Scott on 31 March 2016

I have rust color on leaves in middle an going up to top of plant not sure what it is could use some advice. Hole leaves are turning rust color looks like they are dying off. Please help

By Scott on 31 March 2016

Don't see any resent post all from 2015

By Jennifer ILGM on 1 April 2016

Hi Scott, the post date is when the post was published, but the articles are updated often if not weekly, so you will always get the latest information.

By latewood.ILGM on 1 April 2016


We post here all the time. I see a bunch of posts above your 2 posts and many from 2015. All topics do not have activity unless someone has, or believes they have that issue.

Most of the support we give is at our grow support forum
We have many knowledgeable and expert members always will to help. Sign up today and I think your issues will be resolved.

We have a support ticket in the beginners section of the forum. You can fill it out and allow us to give you informed decisions, instead og guessing.

Peace 🙂

By Joe Gandolfo on 12 May 2016

couple of my plants have white spots on leaves. the rest of them are perfect. my ph levels are 6.5 any idea?

By Cody Martin on 12 May 2016

Thanks Robert awesome information, your a true inspiration. Thanks for all valuable information

By latewood.ILGM on 15 May 2016

Joe Gandolfo,

It could be many things. Young plants can get white spots from you misting plants and light bveing amplified through the moisture and resulting in spots. It could be spider Mites which will present itself on more leaves in the coming days.

I advise you join our Grow support forum and take advantage of the great members, and experts on our site. No one will insult you. We keep it 100% friendly here @ILGM

By latewood.ILGM on 15 May 2016

Cody Martin,

On behalf of Robert me say; "Thanks for your kind words. We try to heelp all aspiring Medical Marijuana growers"

Perhaps you would enjoy the fellowship of our support forum.

By Stoney Burke on 18 May 2016

Alaska Hemp has been promoting for years, I know several growers that have your Grow Bible and this article is just one more example of why you are Alaska Hemp™ Approved.

By thomas brown on 9 June 2016

Silicon will not cause a deficiency in a cannabis plant. yes it is very beneficial if u do provide it,but the info u posted is 100% false.

By latewood.ILGM on 12 June 2016


I do not believe anyone siad that Silicon caused a deficiency. I rerad the post and it states that raily is there a Silicon deficiency.

Thanks for your input. 🙂

By Andre on 8 August 2016

the leaf pic that made me research your add what is that defic? manganese? calcium? this is what i have

By Court on 5 December 2016

The picture above the title (Nutrient Deficiencies In Marijuana Plants) looks exactly like my leaf! What is its diagnosis?

By Merry Skankster on 6 July 2017

What did you do....was it successful?

By latewood.ILGM on 6 December 2016


I suggest you go to our support forum. At our support forum, you can post a picture, and give details in order to help us give you a more informed answer. I cannot in good faith diagnose a plant without seeing it and knowing what grow methods have or have not been applies to same. 🙂

See you there! Peace, lw

By thedude on 1 January 2017

I have a young femonized, autoflower blueberry plant. It is 2 weeks old. They younger leaves look a bit yellow. Temp is going between 70-80, watering with ph of 6, fan is on. I am using miracle gro perilite with organic soil (about 70/30-60/40 perilite to soil). perilite is N-.07%, P2O5-.07%, K20-.07%. I have added a little more N for one watering.

By Merry Skankster on 6 July 2017

What's going on in the top picture? I couldn't find that exact leaf with a diagnosis. Thanks!

By Merry Skankster on 12 July 2017

Checking it out now. Thanks for the info and link. I have rallied through it...I think. Colorado sun and burning through the soil's nutrients faster than I have seen. Ready to learn! 🙂 Thanks!

By Dave on 1 September 2018

I think you should mention the product called hydroguard in your article. Many hydro growers including myself have found that using this product when you have high water temps will prevent and eliminate root rot altogether. This isn't an end all be all solution, however if you can't decrease the water temp any further, this will make all the difference for your ladies.

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