Roots: The Most Important Part of Your Plant!

We all know that buds grow on the top side of a cannabis plant. That’s enough reason for many of us to think that the top half of the plant is ‘the important part’.

But the roots of a cannabis plant are the real workforce behind its success. They might not be directly responsible for growing buds, but they are responsible for many processes that allow bud growth to happen!

Glorious white roots!

If the flowers/bud of a cannabis plant are movie stars (let’s be honest, bud is the star of the show), then your cannabis plants’ roots would be all the hardworking people behind the scenes who do the editing, cinematography, sound, and lighting. In fact, a plant with a healthy root system can lose its leaves and still recover to an extent. But a plant with a healthy leaf system has no chance if it loses its roots.

Here’s what healthy roots look like without soil/coco coir on them – cream-colored or white, with no brown or sliminess

(Click the picture below to see an animated version [3Mb .gif])

Some roots in water!

Today we’re going to show you how to protect your plants’ lovely roots, and your plant will pay you back in sticky home-grown bud!

Note: This is a simplified version of how a plant’s roots work; they actually do some crazy stuff!


What Roots Do for Your Cannabis Plant

Wicking makes it easier for plants to get a drink!

Roots are the base of your plants’ wicking system
In a cannabis plant, the path from a root-to-leaf is like a straw. Water transpires from leaves which creates suction, and this helps pull water through the roots, up through the stem, and back into leaves. This is a super-efficient, low-energy way for plants to get moisture without having to take in as much water through its leaves. However, as plants get larger, their demand for water becomes more than the leaves can handle by themselves. Additionally, your plants will need water to form their first leaves, and that water comes from the plants first root.

Roots Are Necessary to Uptake Nutrients
The roots of a cannabis plant are the main site where nutrient uptake occurs. This means that your roots are the gatekeeper for most of the nutrients your plant gets, and the health of your roots determines how much (if any) of your nutrients are being used.

The leaves of a cannabis plant can also take in nutrients; growers can do this through a method called ‘foliar feeding’, where a nutrient solution is applied directly to the leaves.

The Roots Are the Most Important Part of Your Cannabis Plant
What is a ‘vital organ’? It’s an organ that’s absolutely vital to the life of the organism it inhabits. To a cannabis plant, the roots are its vital ‘organ’.

When a cannabis plant isn’t getting enough nutrients, it’s leaves/stems get damaged, but the roots are left alone. When a plant gets too many nutrients, the leaves get nutrient burn, but the roots are left alone. When a cannabis plant gets overwatered…you guessed it, the leaves/stems are what suffer.

Think of the leaves of a cannabis plant as the first line of defense against less-than-perfect conditions. The leaves can also act as backup systems for a few of the functions the roots perform, such as nutrient/water uptake. But since cannabis plants already have a primary method of water/nutrient delivery (that has better protection by being underground), the leaves become expendable in hard times.



How to Protect Your Roots:
Most problems that people encounter with the roots of their cannabis plant can be boiled down to one of only a handful of causes. These include:

Being “Rootbound” (Not Enough Space for Roots to Grow)
A plant’s size is determined in part by the amount of space the roots have to grow. Once the roots run out of space – known as being ‘rootbound’ – the plant’s growth will grind to a halt unless conditions change. Although this won’t necessarily degrade the health of the roots directly, the rest of the plant will directly suffer in the form of stunted growth.

What You Can Do: Make sure you’re planning to use an appropriately sized pot for your grow. I know that’s harder than it sounds, but luckily we’ve got all the info you need right here! Also, remember that while your plant is in the vegetative stage, you have the option to replant it in a different container if necessary.


Overwatering or Underwatering (Too Much or Not Enough Water)
Overwatering is the term used to describe when there isn’t enough oxygen available at the roots of a plant. This usually happens when there is an excess of water in the medium (not counting DWC), so we call it overwatering. Paradoxically, plants grown in DWC can also show signs of being overwatered if there isn’t enough oxygen in the reservoir water.

Underwatering is exactly what it sounds like. Weirdly enough, if a plant isn’t getting enough water, it starts to suffer in a way that looks just like overwatering.

AN overwatered cannabis plant next to an underwatered plant.

In both cases, the plant will droop which makes it confusing for those who aren’t familiar with the problem. Thinking back to your recent history with the plant can help. If you watered right before the problem started and the soil still feels wet to the touch while the plant is drooping, it was likely overwatered. If you haven’t watered in 2+ days, it’s probably underwatered.

What You Can Do: If you’re having trouble dialing in how to water, check out our page on the subject. If you grow in coco coir, we have a page specifically for that, too!


pH (Acidity or Alkalinity)
The pH of the medium (soil/coco coir/water) your roots are resting in determines what nutrients they can uptake at that time. For example: if you’re growing hydroponically and the pH of your medium is 5.0, your plant will be unable to uptake calcium even if your nutrient water has a lot of it.

The pH range in which nutrients become available is pretty small; only a 1.0 variance for the entire acceptable range if you want to get the essential minerals. In soil, this range is 6.0 – 7.0, while in hydroponics it’s 5.5 – 6.5. That being said, it’s best to avoid getting close to the minimum or maximum for either of those two ranges. The charts below illustrate the pH needed for specific nutrients to become available.

Hydroponic pH chartSoil pH chart

What You Can Do: If you’re using properly amended soil, you’re most likely good to go. Lucky! Everyone else should make a point to check the pH of their root zone often to ensure proper nutrient uptake. Bad pH equates to inadequate nutrient uptake, which equates to damaged-looking leaves and plants.


Root Rot (Pythium)
Although Root Rot is a larger problem for hydroponic growers (such as those doing DWC), it can affect any grow where the roots are sitting in stagnating water. That includes the saucers some growers use underneath those old-style pots. This is far less likely to happen in outdoor grows in soil since water can go further underground.

Root Rot attacking some unsuspecting roots!

Root Rot is especially dangerous because it kills the roots first. In some cases, a cannabis plant can appear to be healthy until the roots have been utterly demolished. Luckily, Root Rot has a tell-tale smell that is absolutely awful. Checking for this smell only takes a second, and it can help you ensure you won’t get surprised by a plant that’s suddenly dying! Of course, this check should be paired with preventive measures (i.e., beneficial organisms), so you’re not just waiting for a problem to show up.

What You Can Do: A proper watering regimen (How Often to Water?) will prevent most root rot issues. It’s also a good idea to add beneficial organisms to your root zone. This way, if pythium does show up, it will quickly be outcompeted by the resident organisms. I suggest Hydroguard as such a product, but Subculture and Great White have also personally given me good results.


Fungus Gnats
Gnats! GNATS! GNAAAAAATS!Of all the pests that can infest a cannabis plant, the Fungus Gnat isn’t the worst. However, they’re uniquely annoying in that they infest your medium and directly attack your plants’ roots. A fungus gnat infestation is a sign of a different problem: overwatered topsoil!

Fungus Gnats need a wet environment to be able to reproduce successfully. Although there are products like diatomaceous earth that directly attack the gnats larvae, making sure not to overwater the medium will make it so they don’t even get the chance. Of course, an especially cautious grower could combine methods for an even more effective means of preventing this pest!

What You Can Do: I hate to say it again, but this is another problem that doesn’t exist unless you overwater. Fungus Gnats need water to procreate, and a semi-dry medium is their doom. Adding diatomaceous earth as additional protection is completely safe and won’t even let them land to try living with your plants!



Jump to…

What’s the Best Pot? Containers Explained

How to pH Cannabis – Best pH for Soil or Hydro

Root Rot

Fungus Gnats



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