root rot weed

Root rot in marijuana

We must avoid the marijuana plant to rot. The plant is rotting when the leaves begin to turn yellow and stop growing. Cure the rot is very complicated, so, we must prevent at all costs the plant sick and this can be done with simple care.

The root rot, scientifically known as Phytophthora

The root rot, scientifically known as Phytophthora, when the leaves of the plant occurs and also even stems buds, put first yellow, brown and then eventually end up falling. The leaves are disappearing and the plant dies.

The root rot arises especially in spring or autumn and when the temperature is between 15 and 24 degrees Celsius. It can occur when the following circumstances: the floor of the plant is too wet, or the plant is in a soil too hot, or has been used in excess fertilizer for cannabis high in nitrogen.

As regards the inside of the plant, the roots, they will also becoming brown (healthy root is white) because longer absorb food; and even the stem also may become brownish color.

When the plant is sick, little can be done. There are people who, seeing the leaves change color, try to irrigate more ground to believe that is due to the lack of water and precisely the opposite effect occurs: the problem is exacerbated.

Once you start to yellow leaves, the cannabis plant can die in just seven days.


As it mentioned previously, once the plant is the root rot disease is impossible to cure. But what it does do is to guide the care of the marijuana plant to prevent and avoid, as far as possible, the plant becomes ill.

Funki Fungi BAC / Stimulator based substrate Mycorrhizas

You can start by choosing a suitable substrate for the marijuana plant, a substrate that does not retain much moisture. You can choose, for example, Funki Fungi BAC / stimulator Mycorrhizas based substrat, a product that caters to the roots of food, water and nutrients needed for the plant to grow rapidly and vigor. Do not be obsessed with watering the plant and you have to keep the soil with good drainage so moisture does not build up. As for irrigation, do not take a hot water plant and not water it in the middle of the day, better early in the morning or late afternoon. If the plant is watered manually, you should be done slowly to avoid running water make holes in the ground and also to prevent the roots are not damaged. It should be added that cannabis is a plant that gets used for irrigation to be provided, that is, if a plant is accustomed to a certain amount of water must be maintained the same amount of water throughout the growing season.

In addition, change the crop water every 15 days. Also, the soil temperature must not be too high. We must also keep clean the whole environment of our crop: utensils, land, and even our hands (it is important that before handling the plant we have washed your hands with soap and water). Even the air must be clean, and this is achieved by aerating the growing area at least once a day for a few minutes.

Yes, unfortunately it is too late and the plant has fallen ill have to get rid of the land where it has been because it is contaminated and all that is planted there run the risk of becoming ill.

You can also prevent root rot using a stone bubble as those with aquariums and thus can ensure that the water used has sufficient oxygen.

The root rot affects less to the crops grown in dry land because they receive little water (though the nutrient intake is also lower and the harvest, therefore, will not be as plentiful). This type of dry land crop pests do not affect them much because they are not subjected to excessive moisture, so it is a kind of ideal crop. Of course, if the owner of the crop live in a humid place, there is no choice but to grow there.

Taking good care of the roots

For cultivating marijuana, surely one of the most important aspects is the number and quality of buds you can get. But we must not forget that the most important part of a plant are its roots. These, supply water, minerals and nutrients that all plants need. If the root of marijuana is healthy, the whole plant, including buds, grow healthy. So now you know: also watch what is not.

also watch what is not

In PEV Grow we want to help you avoid at all costs the root rot and for this you can find on our website the Trichoderma harzianum: protect plants and roots , it is a beneficial fungus that protects the roots of the cannabis plant. This fungus colonizes the roots of the plant by increasing the uptake of nutrients and water and protecting them from diseases. The fungus forms a shield around the roots makes the plant stronger and protects against many diseases.

Trichoderma Harzianum: protect the plant and roots

In Piensa En Verde we have also one of the best bio-stimulants root that currently exist, it is the Rootmax biostimulator Raices Green Hope , a product with which biological processes for bacterial life in the substrate are activated, significantly increasing the root system. And not only that, but the taste and crop production significantly increased. It also prevents mold problems and strengthens the roots in a remarkable way.

Rootmax Bio-stimulator of Roots Green Hope

By Noelia Jiménez, Team Piensa En Verde

Root rot in marijuana: We must avoid the marijuana plant to rot. The plant is rotting when the leaves begin to turn yellow and stop growing.

Root Problems

Table of Contents

Cannabis Plants With Root Problems Show Many Symptoms

  • Cannabis may appear overwatered or droopy
  • Curling or cupping of leaves
  • Wilting – either individual stems wilt or the whole plant may wilt
  • Slow growth, or staying very small for weeks
  • Leaf yellowing, or sometimes even other colors like purple or red
  • Brown spots / Burnt spots
  • Other strange nutrient problems
  • Brown or slimy roots – this is often a sign of root rot
  • Smelly runoff water (smells rotting or musty)
  • Leaves may start dying and falling off rapidly
  • Plants drink much less water than usual

Example of extreme overwatering on an adult cannabis plant

This seedling was being grown in pure perlite, which is not a suitable growing medium for cannabis, and as a result the roots were not getting the proper levels of air and water. This seedling needs to be transplanted to soil or coco (or even into hydro) in order to get better.

This clone was give the same amount of water from when it first sprouted. As the plant started getting bigger and drinking more, this wasn’t enough and became chronically underwatered (a different type of root problem, with similar symptoms). What this particular plant needed was to be given more water at a time. One warning flag was that the plant was drying out every day (you should only have to water your plant every few days, if it’s drying out in just one it likely needs more water at a time). It’s always a good idea to listen to your plants when deciding when to water, as opposed to following a set schedule. Each plant and environment is different, and what works for some plants may not work as well for others!

The cannabis plant below did not have any drainage holes (water could not drain out the bottom of the pot). Notice the strange twisting of some of the leaves. When roots are left in stagnant water for too long, they cannt get enough oxygen and tend to develop root problems.

More overwatered marijuana seedlings – these were overwatered since theyf first germinated. If leaves are drooping down in normal heat, but still seem kind of “fat” it’s often something with watering or roots!

Example of a cannabis seedling with what appears to be a nutrient deficiency, but the symptoms are actually caused by overwatering / root problems

This particular type of cupping of the leaves below is common among cannabis plants with root problems. In this case, the plant had no drainage from the bottom of the solo cup, so water was just pooling at the bottom for the roots to sit in. Once the grower poked holes in the bottom of the cup, this problems went away (the cupped leaves didn’t recover, but new leaves started growing in happy and healthy).

Sometimes leaves will tend to cup or curl down due to root problems, like the plant above, but sometimes the curl upwards too, like the poor plant below (this was caused by poor drainage and plant was overwatered, leading to a pretty severe case of root problems):

This next plant was also overwatered and had no drainage. Notice how dark the soil is and the green algae growing all along the top of the soil – these are more signs the plant has been overwatered for quite a while. You should never water your plant when the soil is still wet at the top, and if you notice lots of algae growing on top of your soil, it may be a sign that you’re overwatering on a regular basis.

The grower went away for a few days, so they chose to overwater their plant in hopes it would be enough water until they got back. While they were gone, they had a huge heat wave. So this plant was subjected to overwatering plus heat. A few days later, when the grower came back, they saw that the leaves were cuppping upwards and had turned lime green. The stems and veins of the leaves were turning red. You can see the soil is still dark and wet because the plant stopped drinking after developing root problems.

Another plant from that same batch which reacted differently

Chronic overwatering in thick soil led to these symptoms. The main thing that alerts you to the fact that the yellowing is caused by overwatering is the fact that it’s droopy. It’s very easy to overwater young plants when you have a small seedling in a big container. When that’s the case, don’t soak the whole growing medium. Water in just a circle around the plant until its leaves are up and growing fast. At that point you can start watering more thoroughly ?

The following seedling is almost a month old, but it’s been overwatered its whole life. As a result, it’s stunted and small. The biggest hint that the roots are at fault is the fat, droopy leaves. The fact that it’s a small plant in a big container also makes it more likely for plants to develop root problems.

The strange yellow and red growth in this picture has been caused by giving the plant too much water, too often. Overwatering can often causes what appears to be nutrient deficencies in young plants! Older plants tend to just droop, but especially seedlings can have really odd reactions to overwatering.

The plants below developed root rot in a hydroponic setup. This is usually triggered when the roots can’t get enough oxygen, usually due to high temps or poor oxidation of the water. Notice the strange burnt appears on some of the bottom leaves. They turned almost white. The whole plant was drooping, especially towards the bottom. The roots turned brown (pictures below).

The plant on the right is healthy, and the plant on the left has root rot. It’s interesting how the symptoms from root problems are often similar, whether the problem is in soil or hydro!

More side effects of root rot

Root rot! No wonder the leaves were having so much trouble on top.

Possible Triggers For Root Problems

  • Heat – cannabis is more likely to have root problems at higher temperatures
  • Cold – cold roots are unhappy roots – cold shock can cause wilting and other problems
  • Over-watering potted plants – too much watering tends to cause root problems
  • No drainage hole at the bottom of the container – if water can’t get out and water is sitting at the bottom of the pot, the roots can “drown”
  • Muddy or thick soil – if your soil is muddy and thick instead of rich and fluffy, it may mean the soil doesn’t hold enough oxygen to support your roots.
  • Small plant in a big container – When a seedling (or small plant) is in a big container, it often has trouble getting enough oxygen at the roots. Until the plant has grown bigger and started to fill up the container, it’s important to avoid overwatering. It can help to water just a little bit at a time, in a circle around the seedling, until it starts growing faster.
  • Plant has “overgrown” it’s container (become rootbound) – The roots of a rootbound plant have started circling the outside of the container, causing watering and nutrient problems even if you’re doing everything right. When this happens, you may need to transplant to a bigger container to stop the plant from being “choked” by the roots.
  • Big plant in a small container – any time you have a big plant in a small container, even if the plant isn’t root bound, you increase the chance of underwatering since the plant quickly drinks up all the water in the soil!
  • Hydroponics – Root problems are caused when there’s not enough oxygen in the water, usually caused because it’s either too hot or there isn’t enough bubbles/aeration

Certain strains are more prone to root problems than others, but good root practices will allow every plant to thrive!

How to Treat Root Problems:

Step 1: Identify what may have caused the root problem (refer to list of possible triggers above)

Step 2: Address this underlying issue

  • Happy temps – Make sure your grow area maintains a comfortable room temperature during the day, and is a few degrees cooler at night. Learn more about how temperature affects your cannabis plants.
  • Only water your plants when they need it. How often should I water my potted cannabis plants?
  • Make sure potted plants have plenty of drainage, and there must be drainage holes at the bottom. If soil or growing medium holds a lot of water, consider mixing in 1/3 to 1/2 extra perlite to “loosen things up” and improve drainage at the roots.
  • Put plants in the right sized container to give the roots the best environment to spread out and grow. You may need to transplant to a bigger container if your plant has gotten too big or its roots are rootbound.
  • Brown, smelly roots? Learn how to get rid of root rot

Step 3: (Optional) Provide your plant with a beneficial bacteria like Hydroguard to help roots recover quickly (more info about root supplements below). Hydroguard will help fight root rot by creating a colony of good organisms to outcompete the root rot.

You May Not Want to Use Hydrogen Peroxide (H2O2) for Root Problems! H2O2 is temporarily effective at best when it comes to root problems. By it’s nature, even commercial grade H2O2 will be completely gone from a water reservoir after about 24 hours as it reacts with the water to form oxygen (decomposes) until the H2O2 is completely gone.

If H2O2 is added to a water source, it kills most of the bacteria in the water, including any good bacteria, but will not usually be able to kill all bacteria, so some bad bacteria will still be left to repopulate. Because of it’s nature, hydrogen peroxide does absolutely nothing to fix the underlying issue that causes root problems, and it kills any postive bacteria in your soil or water so sometimes it can actually make things worse. I think of H2O2 as a temporary bandaid.

I personally recommend using a supplement called Botanicare Hydroguard for root problems because I’ve used it successfully to get rid of a terrible case of Root Rot

Note: Botanicare used to have an awesome root innoculant called Aquashield, but in our tests Hydroguard works even better to create healthier roots and get rid of root rot!

Hydroguard is also much cheaper than most other similar root treatments and is proven to work well at supporting root health in cannabis. Take a look at our root rot page to see pictures of how Hydroguard was able to completely cure a terrible case of root rot.

Other examples of beneficial root supplements include Piranha, VooDoo Juice, Great White (Great White has great reviews, yet is obscenely expensive), Subculture B, Rooters, and Plant Savers. Most of these can be used with both hydro and soil grows. I personally recommend Hydroguard because I’ve used it successfully to treat Root Rot (and it’s also very affordably priced, you can use it throughout your grow without breaking the bank).

One important thing to note is that after you treat the cause of root problems, the old damaged leaves may never recover! With recovery, you should be looking for the problem to stop spreading, and for new leaves to be growing in green and healthy.

Root problems can cause wilting, drooping, nutrient issues, spots & other strange symptoms. Learn the common root problems and how to treat & prevent them.