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Guide to Cannabis Root Problems

A Complete Guide to Cannabis Root Problems

Humans have been cultivating marijuana for thousands of years. However, in recent decades, growing techniques have been perfected. While it may seem like a person could grow cannabis alongside any other vegetable or flower in their garden, cannabis cultivation has become incredibly precise to give growers the high-potency, heavy yielding strains that most people expect. One area in which growers have fine-tuned their cannabis cultivation expertise is in caring for the plants’ root systems.

Healthy Root Systems are Essential

No matter how well a cannabis plant is cared for, it cannot thrive without a healthy, robust root system. The root system is the foundation from which the cannabis plant grows and ensuring its vitality is the first step in growing the perfect cannabis plant. Roots absorb vital nutrients and water that the plant needs to grow.

The health and size of the root system determine how large a plant grows and how well, making it vital to care for them properly. Without healthy roots, cannabis plants will experience devastating damage, including yellowing leaves, reduced growth, weak buds, or even death. If you notice any of these signs early enough in your kush or gorilla glue plant’s grow cycle, be sure to refer to our list of disease and pest guide topics here.

Signs of Root System Issues

Of course, it is not possible to get a full picture of a cannabis plant’s root system when it is buried in soil or any other growing medium. Therefore, growers must be familiar with how the plant itself shows issues with the root system, which include:

Curled or Sagging Leaves

Curled or sagging leaves is one of the very first signs that there is an issue with the roots. The edges of each leaf will curl up or down, and the plant will have a sagging, water-logged look to it. This symptom is quickly followed up by more severe symptoms of root damage.

Leaf Edges are Burnt

Another early sign of root problems is the tips and edges of the plant’s leaves looking burnt. This can happen as the result of root rot, which is a fungus called Pythium that develops when there is excess water and a lack of oxygen at the root level of a plant.

Leaves Turning Yellow, Red, or Pink

Some cannabis strains naturally have a red purple tint on stems or and large fan leaves, but if growers notice a mottled red or pink color on their leaves, it could show a problem with the roots. When roots are damaged by water that is the wrong pH it can cause nutrient lockout, which will deprive plants of vital nutrients, such as phosphorus.

Yellowing leaves can indicate a few different problems with the roots. The plant may be root bound, suffering from root rot, or have a fungal infection that is attacking the roots.

Brown Spots

Cannabis plants that have an acute issue with root rot may have leaves with widespread bronze or brown spots. This will become more severe as the plant’s root system has a harder time absorbing water.

Leaves Falling Off

As root issues progress, the plant can no longer keep leaves alive. In addition to the other problems with the leaves, growers will notice that their plant is losing leaves at an alarming rate.

Brown, Slimy, or Odorous Roots

Plants with a severe root rot problem will have slimy, brown roots that give off a terrible, rotting smell. Growers that can see part or all of a plant’s root system should inspect it for issues with the color and texture, but the smell will be hard to miss even if the plant is grown in soil.

Causes of Root System Issues

Preventing root system issues is critical in getting the most out of your indoor marijuana seeds. To do this, growers must be familiar with what causes root system issues in the first place, which include:

Excessive Heat

Cannabis plants are more likely to develop issues with their root systems if they are consistently kept at temperatures that are too high. High temperatures facilitate the growth of bacteria and fungi at the root level, which will speed up root rot.

Excessive Cold

Similar to excessive heat, excessive cold will cause problems for a cannabis plant’s root system. Rather than causing a rotting issue, cold temperatures shock the roots of the plant. This will cause them to wither, reducing the vitality of the entire plant.


One of the most common causes of root issues in cannabis plants is overwatering, especially those grown in pots. This is because roots need oxygen as much as they need water, and overwatering deprives them of that. Without oxygen, nutrient uptake is inhibited, and many other plant processes. Additionally, roots that are not allowed to dry a bit between waterings are more likely to develop root rot. Don’t mistreat your blue dream or wedding cake pot plants by giving them too much water. Instead follow a watering schedule that allows them to almost dry out in between each drink.

Lack of Drainage

Plants grown in pots that do not have adequate drainage are more likely to suffer from complications related to overwatering. Even if the surface of the soil appears normal or somewhat dry, the roots towards the bottom of the pot will be submerged, leading to a lack of oxygen and root rot. Try out air-pots for an option that is a little more costly, but offers impeccable drainage and root oxygenation.

Thick Soil

One of the most important factors in a successful cannabis grow operation is the quality of soil in which the plants are grown. Not only is this critical to the amount of nutrients the plants have access to, but it is essential for the plants to have healthy root systems. Thick soil will be harder for the plants’ roots to penetrate, limiting the overall growth of the plant. Whether you grow your outdoor cannabis seeds in pots of soil or right in the earth, you’ll want to give them the best soil to grow in.

Not only will the roots be unable to stretch, but muddy, thick soil often holds water for longer than properly aerated soil. This causes the roots to stay saturated for an extended period, leading to root rot.

Wrong Container Size

For cannabis growers who are using containers to grow their plants, the size of the containers plays a vital role in the health of the plants’ root systems. Cannabis plants grow quickly, and the roots grow even faster than the parts of the plant above the surface. This can make it challenging for growers to know what size pots to use, causing them to use pots that are either too large or too small.

Too Small

Most people are familiar with what happens when a plant’s pot is too small, and american weed seeds behave exactly the same. In this circumstance, a plant will become root bound, causing serious issues for the plant. When this happens, growers may notice that their plants dry out much faster than they used to and that plants look sickly. This is because the plant does not have enough access to water and vital nutrients to sustain its size in such a small space.

Too Big

Many growers assume that preventing a plant from becoming root bound means putting it in the largest pot possible right away. However, growing a cannabis plant in a pot that is too large has a negative impact.

Small plants in large pots are at risk for being over watered, as growers attempt to soak all the soil when watering. This is far too much water for a smaller plant and will limit its access to oxygen. If a grower uses a large pot, they must be sure to water small amounts around the base of the plant and monitor it closely for signs of overwatering or dehydration.

Growing premium weed seeds hydroponically has become popular in recent years, largely because of how precise growers can be in the amount of nutrients to which plants have access. However, using this method is very finicky, and minor mistakes can have dire consequences, especially for the root systems.

When growing plants hydroponically, growers must be sure their plants are receiving enough oxygen by aerating water before adding it to their plants. Additionally, water is often too warm, which increases the risk of suffocation.

Treating Root Problems

There are few options for treating extensive root problems, and some damage may be permanent. Many growers are told they can add hydrogen peroxide to the water they give their plants to combat root problems, but this is not the best way to treat root problems. Hydrogen peroxide may kill some bacteria present in the water and soil, but it will leave some behind.

Hydrogen peroxide does not stay in the soil for very long, lingering for about twenty-four hours at the most. If the main cause of the root problem is not addressed, the problem will come back as soon as the peroxide treatment wears off. Growers must eliminate the cause of the root problem before taking any steps to mitigate the damage.

Some growers add beneficial bacteria to their soil to combat root issues, like root rot. Pest control is another important aspect in avoiding root rot, as some insects carry fungi that causes cannabis plants to develop the problem faster.

The Bottom Line

Keeping the root system healthy is key to a robust cannabis plant and high-yield harvest. Growers who understand how root problems develop, how to prevent them, and how to manage it once they happen are better equipped to get the best result from their plants.