December 18, 2018

It sucks when you have sick plants. It’s similar to having a sick child or a sick pet. It’s hard to watch something near and dear to you become sick and suffer, even if it’s just a plant. Cannabis plants are more than “just a plant”. They are the result of months of blood, sweat, and tears.

Some cannabis plants are heartier than others. Certain strains are more susceptible to rot. Others tend to mold or become infested with mites. It’s important for you to be able to spot the signs of a sick plant, you know, before it’s too late.

Yellow Leaves

Did your plants’ leaves turn yellow all of a sudden? You definitely have sick plants on your hands. Your plants most likely have the beginning stages of rot. Bud rot is easy to fix, as long as you get to it in time. Try turning up the heat a little more. Cold plants are more prone to rot. Make sure your plants are in an environment warmer than 68 degrees F/ 20 degrees C. The humidity in your grow room could also be too high. It may help to trim your plants, so they’re less bushy. Lastly, trim the infected buds ASAP, lest they infect the healthy plants!

Flowers Turning Brown

Are your flowers turning brown and subsequently dying? You could have broad mites. Despite what the name suggests, broad mites are incredibly small and very difficult to see. Mites will make your flowers turn brown and die if they are not taken care of. Take a look at your new growth. Does it look wet and slightly twisted, like a scary old tree? You’ve most certainly got mites. Luckily, there are sprays you can get to treat mites. Make sure you spray them daily!

If your leaves look like this, it’s probably a calcium deficiency. Image source:

Dead Spots and Crinkly Leaves

Do your sick plants have dead (brown) spots and leaves that are starting to crinkle up? There’s a strong plant that your plants have a calcium deficiency. Another tell-tale sign is that your plants appear to not be growing, or the new growth appears smaller than it should. Typically with calcium deficiencies there are deficiencies in other nutrients as well. The best way to do this is with a calcium supplement. Your best bet is to use a cal-mag (calcium and magnesium) supplement.

Leaves that are Yellowish Brown Directly Under the Lights

If the leaves directly under your lights are starting to turn an ugly shade of yellowish brown, then there’s a good chance that your sick plants have a case of light burn. This malady isn’t as serious as some of the other ones. This is more common among the older leaves, the ones that have been exposed to light the longest. Light burn is often a sign of a nitrogen deficiency. The best thing you can do first of all is move your lights further away from your plants, or tilt your plants away from the lights. Reducing your light intensity might help, as well as a nitrogen supplelment.

Featured Image Source:

Do you have any advice for others with sick plants? Tell us in the comment section!


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  1. By Grass Chief

    ,09 Nov 2017
    Very helpful and educative post. Like the guidelines and tips shared here to make marijuana plants more greener and better. Exactly cannabis plants are more than “just a plant”. They are the result of months of blood, sweat and tears.
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  2. By Stoney smurf

    ,11 Nov 2017
    The post is very good info that actually works. I always grow organic and i use black molasses non sulpher i use i dime shot to 1 bucket of water every 3 weeks for my cal , mag supplement , […]Read More
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  3. By jerry

    ,28 Nov 2017
    The guidance of a sick plant and other deficiencies’ would be a nice resource to look at with pictures and a nice chart to resort to when things happen for those who have not experienced any issues(eh,ehm, like that’s never […]Read More
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    1. By jerry

      ,28 Nov 2017
      oops, looks like you already have that here, thank you
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  4. By RYNO

    ,24 Jan 2018
    My plants are showing signs of white powdery mildew. I’m seeing this for the first time and it’s my 1st attempt at using grow bags. I’ve been using apple cider vinager to control the PM but it’s becoming a pain […]Read More
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  5. By Cachadream

    ,09 Feb 2018
    I had same problem month ago, used spray of 500mls water, 2 table spoons of Soda powder, 2 table spoon of vegetable oil and 1 tea spoon of non harmful washing up liquid (emulsifier) Spray plants making sure all plant […]Read More
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  6. By Carol

    ,30 Aug 2018
    I started my first ever 4 plants in April and they were transplanted the end of May outside. They did great up until a month ago (first part of August) when they developed light green spots on most of the […]Read More
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    1. By latewood_ILGM

      ,30 Aug 2018
      Carol, The best way for us to help you is to invite you to join our support forum where we are set up to help you. As a member you can post images and discuss the issue daily with our […]Read More
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  7. By Cotton top

    ,25 Sep 2018
    Three weeks to harvest help problem with powdery mildew ,reply 😟😟
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    1. By latewood_ILGM

      ,04 Oct 2018
      Cotton top, Join our forum at: for real time replies to your question. There are commercial sprays, and homemade remedies. Best to throw this out in the forum or search for “how to treat plants with powdery mildew. Look […]Read More
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