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Want Big Cannabis Buds? Start at the Roots

By Chris Bond | Last updated: May 26, 2021
Presented by Sipco
Key Takeaways

The importance of root health for cannabis plants can’t be understated. If you want big buds, you need thriving roots.

Just as a weak foundation won’t support a building properly or for a long time, weak cannabis roots won’t serve to support your cannabis plant. The development of healthy branches, stems, nodes, leaves, and flowers are all dependent upon a thriving root system. Unfortunately, though, since you can’t usually see the root system, it is often too late before root damage is noticed, and usually the damage is irreversible at that point. By taking a few simple steps, you can give your cannabis crop’s roots all the nutrition and advantages they need to support the production of those buds that you love. First, let’s look at some of the basics of roots.

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Grower displaying roots of a cannabis plant grown in rockwool.Grower displaying roots of a cannabis plant grown in rockwool. Source: OpenRangeStock / Shutterstock

A Primer on Roots

Your cannabis roots perform many vital functions. They help anchor the plant into the ground or medium in which they are cultivated. Without this function, the plants would require support structures to keep them from falling over, especially during flowering when the branches hold more weight as the buds develop. Equally important, if not more so, the roots serve as the conduit between the water and food that your plants need and the branches, leaves, and flowers that need them.

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They absorb and distribute water and nutrients to the plant through networks within the plant’s vascular system, driven by capillary action. Thirdly, they store the food created by the leaves during photosynthesis and release it as needed during critical periods of development.

As your cannabis root system develops, like many other genera of plants, it forms three distinct types of roots. Most folks are familiar with two types; tap roots and fibrous roots. These two types of roots are usually unseen as they almost always develop and grow into the media in which they are planted.

Read also: Enhance Your Plant's Root System

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A third type of root cannabis plants can develop are called adventitious roots. These don’t always develop, but often do with favorable conditions in humid environments. These form at or above ground/soil level on the plant and grow towards the substrate or media they are being cultivated in. Cannabis can be easily propagated by taking a cutting with these roots and transplanting them into their own media. This phenomenon is often seen on the bottom branches of plants when they are near the ground or media.

It is no understatement to say that without healthy roots, the rest of your cannabis plant will cease to thrive. If your plant is starting to struggle and there are no obvious outside forces such as pests, low light levels, or extreme temperature threatening your prized plants, then there is a good chance your problems lay in the roots. If your entire plant suddenly starts wilting or the stems and leaves begin turning yellow, there is an excellent chance the problem started in the root system.

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There are many plant deficiencies your cannabis plant can bounce back form, but unhealthy roots often aren’t one of them. Keeping them healthy is vital to good yields. Let’s now consider some ways to ensure the biggest buds, nurtured by healthy cannabis roots.

Read also: Rockin’ the Rhizosphere

Boosting Your Cannabis Roots’ Health

If you want big buds, then you need to foster big, healthy roots — no two ways about it. One of the easiest ways to ensure good root health is to provide proper levels of water. Just as we cannot breathe while fully submerged in water, your cannabis roots can’t “breathe” either. Overwatering a cannabis plant will often lead to it collapsing. Make sure to use a well-draining medium for this. I know, you may ask how they can be grown hydroponically then, but in a hydro system the water is being re-oxygenated, so the roots are getting their oxygen through the water instead of the air. Conversely, just as we would not survive without water, neither will your cannabis plants. Keeping the soil or media evenly moist is critical to healthy roots and large buds.

Keeping your plants at an appropriate temperature will also help develop strong roots and by extension, healthy buds. Cannabis roots grow best in warmer temperatures. Keeping the growing substrate at a temperature between 70°F and 85°F (21°C to 29°C) is optimal. Making sure your roots have enough room to grow will also help your cannabis plant thrive.


Visible roots of plant outside of its pot - time to repot in larger containerIf the roots are visibly pushing up against the inside of the pot, it is time to repot them into a larger container. Source: Shutterstock / Dmytro Tyshchenko

Roots Need Room to Roam

Cannabis roots that have outgrown the space allotted to them will become rootbound. If this condition is caught early enough, it is easily remedied. If not, then your cannabis plants will be stunted and may not ever produce any buds, or only very weak ones. It is important to check on the roots periodically to make sure they are not getting too crowded. This is difficult to do when plants are field grown, but it is extremely rare for conditions to exist that favor root binding. This is far more common in cannabis plants grown in hard-walled containers such as plastic pots. If the roots of the cannabis plant start pushing out of the bottom holes in the pot or are visibly pushing up against the inside of the pot, it is time to repot them into a larger container to keep the roots growing and supporting your plants. Some growers choose fibrous containers to avoid this. This allows for the roots to start growing through the sides of the fiber and then get “air-pruned” which keeps them from getting rootbound.

Read next: Cultivating Cannabis: Root Mass = Fruit Mass

Keeping your substrate at the appropriate pH will also help roots stay strong and viable. The ideal pH range for healthy roots and great buds varies somewhat depending on growing media and specific species of cannabis. In general, though, for hydroponically grown cannabis, the pH can be as low as 5.5; for soil cultivation it can be as high as 7.0. In either case, root health will decline if the pH is too low or too high. When the pH is too low, nutrient toxicity can occur with the elements aluminum (Al) and manganese (Mn). Root tips will be harmed by high aluminum levels. Root diseases such as Fusarium and Cylindrocladium thrive in low pH environments as well. When the pH is too high, other nutrient imbalances can occur that interfere with vital plant functions such as photosynthesis. If photosynthesis does not occur, or is otherwise impeded in some way, then the root growth is stymied, and the plant will fail to or cease to produce valuable buds.

There are also naturally occurring root enhancers that can be added to your crop (or may already be there). These can cohabitate with your cannabis roots in a symbiotic relationship. One such helper is a fungus known as Trichoderma. It is commonly occurring in nature and exists in most soils. It works by occupying space around the root system which effectively blocks out potentially harmful biota. It also engages the plant’s immune system by invading the outer layers of the roots, which triggers one of the plant’s self-defense responses. This is the equivalent of getting immunized with a small amount of a pathogen so your body can build up antibodies against it when or if it is reintroduced to your system. Numerous other beneficial bacterial and fungal additives are available on the market, each with a different mode of action, but each having a positive effect the overall health of your cannabis roots.

Big blooms start at the bottom, so keep your cannabis roots healthy and happy and more often than not, your plant will reward you with luscious buds.

Read next: Beneficial Microbes: A Closer Look at the Microbes Living Around Your Plants’ Roots

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Written by Chris Bond | Certified Permaculture Designer, Nursery Technician, Nursery Professional

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Chris Bond’s research interests are with sustainable agriculture, biological pest control, and alternative growing methods. He is a certified permaculture designer and certified nursery technician in Ohio and a certified nursery professional in New York, where he got his start in growing.

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