Marijuana plant leaf problems

If the leave on your marijuana plants are dying off for reasons you can’t explain, it is time to figure out how to fix marijuana plant leaf problems.

There are generally three reasons for the dying off of your plants’ leaves: a pH imbalance, too much or too little water for your plants, or nutrient deficiencies and toxicities.

Make sure to download my free Grow Bible for more information about how to increase terpenes.

Read this article and learn how to recognize leave problems and how to fix leave problems.

Start with the possibility of a pH imbalance and go from there to diagnose the problem and find a way to fix it before it’s too late.

Calcium deficiency

Fix calcium deficiency in hydro marijuana
Calcium deficiency in marijuana plant

Signs of dying marijuana leaves

If you start noticing that your leaves are discolored, they are probably starting to die off. This discoloration can come in the form of yellow, brown, grey, or even red.

The leaves might be curling one way or the other (up or down), or just dropping off the plant after yellowing or browning, signifying their death.

Soil fix

How to fix sick marijuana leaves

In order to know how to stop the trend of leaf death that is plaguing your plants, you are going to first need to know which of the top three causes is at fault. Is the pH level in the roots imbalanced?

fix sick marijuana leaves
Fix sick marijuana leaves

Have you been over or under-watering your marijuana plants? Are there nutrient toxicities or deficiencies that are causing the problem?

These are all questions you need to ask yourself when trying to know how to fix the problem.


pH imbalance

A pH imbalance is the most common reason your plants will be struggling with keeping its leaves happy and healthy.

This is simply because the correct level of pH is necessary before your plant can even take in nutrients.

That, in turn, means that a fixed pH level could actually solve any nutrient deficiencies or toxicities that your plant is having.

So, whenever you see that something is off with your plant, always check the pH level near the roots before doing anything else.

ph imbalance marijuana plant
ph imbalance marijuana plant

In case you haven’t delved into the topic of pH before, the pH scale measures the acidity and alkalinity of a solution, gauging it via a range of 0 through 14.

If it’s lower than 7, the solution is acidic. If it’s higher than 7, the solution is alkaline.

Therefore, the pH level of 7 is perfectly neutral – pure, uncompromised water has a neutral pH level.

You don’t need to be a scientist to check the pH level of the soil. The most important part to check is the soil right around the root system of your plant.

While the pH level doesn’t need to be perfect, it will enable you to figure out if there is a pH balance problem.

It is useful to allow the pH range to fluctuate a bit over time because this will actually allow certain nutrients be absorbed at different rates, which can be helpful to your plant.

You will need to have a way of maintaining and managing the pH level throughout your plant’s life.

One way to do this is by testing the water/nutrient (or supplement) solution before you feed it to your plants.

Simple use something like pH Up/Down to adjust the pH level until it’s within the ideal range. You can do this by using natural means, as well.

You can add vinegar to the solution to lower the pH level, for instance, or you can simply whisk the water (which adds oxygen) to bring the pH level up.

Another way of raising the pH level is by adding dolomite lime to the soil. This has the added benefit of also adding calcium and magnesium to the soil medium.

The ideal pH level for roots to absorb all nutrients efficiently is between 6 and 7. Any higher or lower than that, and you could start running into problems.

If you are using a hydroponic growing system, however, then you are going to want to range to instead be between 5.5 and 6.5.

If this adjustment before feeding your plants hasn’t solved the problem, there are other ways to check and adjust the pH level.

If your plants are in pots of some sort, you should try collecting the water that is draining from the holes on the bottom.

This runoff water should be tested for its pH to see what really goes on near your roots.

If you feed your plants a nutrient-water solution that was at a pH of 6.0, for instance, and the runoff water measures up to a pH level of 4.0, you know there is a buildup of some nutrient that needs to be removed before your plant’s roots can function properly.

This buildup affects the pH level of the soil around your plant’s roots and, therefore, keeps the roots from effectively absorbing all the nutrients they need to.

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You can remove a buildup (such as a salt buildup) by flushing the system with three times the normal amount of plan, pH-balanced water.

After that, you can feed them normally, but make sure to continue monitoring the pH levels to know if the flush was successful.

Some growers perform a routine (every 3 weeks or every month) flush of their plants anyway to prevent buildups from occurring.

This is probably not crucial, however unless you consistently give your plants too many nutrients.

If you’re growing in a hydroponic system, the pH tends to rise over time as the oxygen content in the water increases.

Your best way of ensuring a stable pH level is checking consistently until you are familiar with how the pH level rises or lowers in your particular system.

Watering problems

If you have fixed the pH level and your plants are still experiencing dying leaves, you need to look elsewhere for the cause.

One such cause could be the incorrect watering of your marijuana plants. You can diagnose what the exact issue is depending on your growing medium.

Overwatering seedlings marijuana plant
Overwatering seedlings marijuana plant

If you are growing your plants in soil or in coco coir, for example, (or another similar soilless medium), the problem most likely lies with poor drainage, too much watering, or too little watering.

You can follow certain steps to ensure that your plant is receiving the right amount of water.

Also read “When is the best time to water weed plants

Each time you are watering your plants, you should add the correct amount to make sure about 20% of it has drained out as runoff water.

After you have done this, wait to water them again until the soil is dry enough.

You can establish if the soil is dry by poking your finger in and making sure it’s dry until the top knuckle.

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Of course, if you are growing your plants in a hydroponic setup, then over or underwatering will not be the issue since you don’t even water your plants.

They could, however, be “drowning” due to a lack of oxygen. Use an air stone to get more dissolved oxygen into the water.

If your plants have root rot (whether in a hydroponic or soil-based growing system), the roots will be brown, mushy, and stinky.

This can also come from improper watering, poor drainage, or high temperatures – then again, sometimes root rot seems to appear out of nowhere, for no logical reason.

If your plants do get root rot, get rid of it with Aquashield. Other root supplements that can be used are Great White and Subculture B.

Nutrient issues

If you have ensured that improper watering or an imbalanced pH level aren’t the issues, then your plants likely have a nutrient deficiency.

Nutrient deficiencies in marijuana plants
Nutrient deficiencies in marijuana plants

You should read up on the symptoms of each nutrient deficiency (or toxicity) to establish which one your plant is struggling with.

Also read the article Nutrient deficiencies in marijuana plants for a list with pictures of all possible nutrient deficiencies

List of marijuana plant symptoms

Leaf Color:

  • Yellow
  • Brown
  • Grey
  • Red

Leaf Symptoms:

  • Curling up of edges
  • Curling down of edges
  • Falling off
  • Leaf death

When it comes to the pH level, it is valuable to know that the nitrogen content in a nutrient system has the strongest effect on the pH of the water.

You, therefore, can use this to mix the right nutrients together according to the current water pH levels, so the nutrients are self-correcting the pH level without any extra hassle.

FAQ about yellow marijuana leaves

Why do marijuana leaves turn yellow?

Here are the top 5 reasons that can turn your cannabis leaves yellow: Root pH, Poor Watering Practices, Nitrogen Deficiency, Heat Stress / Cold Shock, and Iron Deficiency

What are the symptoms of nitrogen deficiency in marijuana plants?

Here are three main symptoms of nitrogen deficiency in marijuana plants: Leaves turn lime green or pale all over, Yellow leaves appear at the bottom, and Yellow leaves feel soft.

How to fix yellow marijuana leaves?

In order to fix yellow marijuana leaves first you need to find the actual cause of it. Here is a list of things you should check: pH imbalance, Nitrogen levels, Iron levels, and Watering practices. Once you find the root cause, then just fix that particular cause and your marijuana plants will be back to green.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible


Avatar for Robert Bergman

Robert Bergman


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

31 comments on “Marijuana plant leaf problems”

  1. Over abundance of rain this year and the plants outside are losing its leaves. Turning brown and falling off. Leaves look terrible. Will the buds be okay yo harvest if they make it.

    • Hi Gale,

      Thanks for your message. You will want to be wary of any bud rot issues in that case. Excessive rainfall and humditiy can really allow mold to thrive.
      It may be a good idea to start covering your plants to shelter them from the heavy rainfall. You can use a tarp to do this. You can take it off if you get some sunny and dry weather.
      Try and make sure that there is still some room for airflow as you will otherwise still risk bud rot.

      Let us know if you have any further questions, of course!

      Happy growing,

  2. Great stuff. Got some outside in FL sun.had some yellow leaves the Big Fan 1z. I just put it in a bigger pot .the root ball filled up old pot. So I’m hoping it springs back. Love your stuff. What I really need is some auto flowering seed that can grow in Florida Sun,weather.

  3. Thanks,i will i was checking to see if it was ok to flush plants and start back with cal mag and grow big also was trying to find out what plant looks like a beginning of flowering stage.

  4. This whole site is amazing. I’ve learned more here than anywhere else. Thanks for putting out all of this information. The Grow Bible is excellent as well. Thank you!

  5. I have done everything- just tried ph up because my leaves again began to yellow slowly bottom up- tip up – LED LIGHTING coco coir- black widow, indoor, grow tent , 16:8 lighting schedule and Bergman fertilizer / I have read everything and I get the same problem every time.

  6. Thankyou four of the seeds came out liked dirt weeds, lIt was like I got a batched if bad seeds, or someone is sending out bad seeds, n taking the real seeds

  7. Okay so I’ve not been able to find it unless I’m looking in the wrong spot. The plant leaves are curling up on the edges so what do I do about that?

  8. Put my plant out in the sun for the first time today and at least look like they’re bleaching White

  9. John, You should go to and post some pictures. Fill out a “Support Ticket” so we know what you have done. No way to tell from your brief post. happy growing.

  10. Can genetic deficiencies B exacerbated by the mother plant. I’m having great difficulty understanding what’s going on with these autoflowers. I have several other control plants receiving the exact same treatment but not having the discoloration and stunted growth.

  11. When I started 12 on 12 off lighting my leaves started falling off while there still green. Whats up with that?

  12. Thanks for the helpful info! Particularly the stuff about using pH adjusting agents besides pH UP & pH DOWN.

    My entire autoflower plant keeps going yellow in Week 7 literally overnight. It’s happened twice now. It must be a nitrogen issue, as I only fertilize with mild natural fertilizers like grass tea & diluted urine. But it only shows itself in the first real week of flowering (Week 7). I always assumed plants needed nitrogen most in the vegetative stage, but apparently they require a ton of it once flowering takes off because those buds start cannibalizing the leaves very quickly. I grow in Black Gold Organic soil in a 3-gallon fabric pot under 84 watts of CFL + 20 watt LEDs. Everything looks GREAT until Week 7, then she goes from lush & green to bright yellow in a 24-hour period. Then the bottom leaves start going crisp & limp & falling off and the carnage moves up the plant. But the yellowing happens all at once.

    Very odd & striking how rapidly it occurs. The bud sites try very hard to stay green & grow big but I’m sure they’re not reaching their full potential with the rest of the plant dying off.

  13. My plant is being grown outside and is in the flowering stage. My big leaves are turning yellow and dying off. Not the leaves on the bids but a lot of the lower leaves below the bids is this normal during the flowering stage? If not what should I do about it?

    • Yes, fan leaves yellow and die off in flower as they lose their ability to produce sugars for the plant.

      Happy growing

  14. Hello. We seem to be having MAJOR LEAF LOSS & the leaves are ‘quite’ HEALTHY looking. From the middle down to the BOTTOM of the plant is where it’s occurring. Our PH GUAGE is a 1-8 scale & we’re reading a 7! Unless our guage is off, this isn’t a DESIRABLE read? In the event our guage is WHACK, can you advise where to buy a BETTER one? Thanks.



    P.S. Last year we used regular soil (Dr. Earth Organic) & this year we went with an organic COIR & PEAT soil. We didn’t have healthy LEAVES dropping last year, like this. HELP!?!

    • Conrado,

      We are not really set up for the support you need here in the Blog comment section.

      I advise you to join our support forum where we can help teach you how to grow successfully. Very friendly and sharing community.

      Ph for soil is 6.5 PH for Coco which is a pain in the butt to learn to grow in can be PH’d at 6.1-6.5 A PH of 7 indicates too high a PH. Cannabis enjoys a slightly acidic PH. 7.0 is neutral.

      Join the forum at

  15. can someone post a pic of normal Blue Dream and Gold Leaf in vegetative state? I’m a newbie and can’t tell if mine are healthy with a colored strain or if they have a problem.

  16. what flower that keeps bugs away from your plant by its natural protection system – mites are a problem I would like to plant in the bag next to the plant.

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