Healthy Plant Roots for cannabis

Healthy Plant Roots: The Importance of the Root Zone for Cannabis Plants

I don’t know about you, but when I close my eyes and think about my garden, all I see is a sea of lush canopies and chunky buds. Yet, in my decades of cultivating, I’ve often seen many overlook the true heroes… The ones beneath the surface: The roots.

The underground networks play a pivotal role in your plant’s health and without thriving roots, you will never achieve those lush canopies or chunky buds. So let’s dive deep into the universe of healthy plant roots and learn how to make yours flourish!

Healthy Plant Roots for cannabis

What do Healthy Plant Roots In Cannabis Look Like?

A picture-perfect root system in cannabis is typically bright white with countless hair-like structures branching out. Now, picture-perfect fibrous roots are never the reality but we want to get as close as possible by giving the root zone an optimal environment.

Healthy roots are teeming with life and activity, and, on the contrary, unhealthy plant roots might exhibit brown roots, feel slimy, or even emit a foul smell indicative of root rot vs healthy roots.

In a hydroponic systems, healthy hydroponic roots should also showcase a pristine white hue, looking dense and vital. Roots in hydroponic systems are easier to check up on than soil systems (for obvious reasons).

How to Use Root Stimulators

The Functions Of Roots

Roots do more than just anchor the plant. They absorb root nutrients and water from the soil and pass it along to the rest of the plant essentially feeding the entire plant. They also store excess nutrients for future needs and provide stability against physical disturbances.

Cannabis Roots During Flowering

When your plant enters the flowering phase, it’s all hands on deck for cannabis growers. Roots play a vital role in transporting essential nutrients for root growth and other vital minerals that help the flowering process. During this period, both the primary and secondary roots work overtime to ensure the buds get all the energy they need.

In fact, feeding your root zone with the right combination of nutrients and microbes (beneficial bacteria) can help your plants make buds bigger during flowering.

How to Keep Cannabis Roots Healthy

1. Oxygen

Roots need oxygen to breathe and metabolize. Ensure your growing medium is aerated, especially in hydroponic systems.

If you grow in pots, you may want to consider fabric pots (like Spring Pots or Smart Pots) to help your cannabis root growth with “air pruning”. The fabric in the pots allows roots to grow out of the walls of the pot instead of getting root bound. Stimulating more root hairs, adventitious roots, and a stronger overall plant.

2. Temperature

Too hot or too cold, and your roots will suffer. Aim for a root zone temperature of 68°F to 72°F for optimal health. Make sure to have space between the plants to allow airflow between pots. 

3. Water

Overwatering is the bane of many growers (especially when performing a flush). Ensure the water can drain easily from your medium and that you’re not leaving roots submerged or soggy by stagnant water.

4. Nutrients

While roots crave nutrients, too much of a good thing can lead to nutrient burn. Use a balanced, high-quality nutrient mix and monitor the pH levels. Cannabis plants absorb nutrients most efficiently when the growing medium has a pH between 6.0 and 7.0 (slightly lower for hydroponics 5.5-6.5).

In the words of growers before me, “Feed the soil, not the plant”.

Find all our cannabis nutrients here

Troubleshooting Cannabis Root Problems

Roots, being the lifeline of the cannabis plant, face various challenges. Addressing these promptly can make the difference between a bountiful harvest and complete crop failure.

1. Over/Underwatering


  • Yellowing of leaves, particularly starting from the bottom and working upwards.
  • Leaves feel brittle when underwatered or too soft and limp when overwatered.
  • Growth becomes stunted; new leaves may appear smaller than usual.


  • Check the moisture content of your soil or medium before watering. A simple method is the knuckle test: insert your finger up to the knuckle. If dry, it’s time to water. As you get more experienced you will learn how to gage the water needs by feeling the weight of your pots. 
  • Ensure pots have sufficient drainage holes. In hydroponic systems, check the water intervals and duration.
  • Consider using moisture meters for a more accurate reading.

2. Fungus Gnats


  • Adult gnats flying around plants, especially after watering.
  • Larvae and shiny trails can be visible on the surface of the soil.
  • Seedlings and younger plants show reduced growth rate due to root damage and unhealthy roots.


  • Reduce the topsoil’s moisture. Allow the top layer to dry out before watering again.
  • Introduce natural predators, like Hypoaspis miles, which consume gnat larvae.
  • Sticky yellow traps can catch adult gnats, reducing the reproduction rate.

3. Root Rot


  • Roots turn brownish and have a slimy texture.
  • The distinct foul odor emanates from the growing medium.
  • Above-ground, plants wilt and have a droopy appearance.


  • Improve the drainage system of your growing medium.
  • For hydroponic systems, ensure the water is oxygenated sufficiently. Consider adding air stones.
  • Introduce beneficial microbes to outcompete the rot-causing pathogens.

4. Root Bound


  • Roots circle the bottom and sides of the pot, forming a thick mat.
  • Plant growth becomes stunted, and yields can drop significantly.
  • Nutrient deficiencies appear even when feeding is regular.


  • Regularly transplant young plants into progressively bigger pots.
  • If plants are mature, consider root pruning but approach with caution.
  • Fabric pots can help air-prune the roots, preventing them from becoming root-bound.

5. Poor Root Structure


  • Plants are unstable in their pots.
  • Growth is slow, with weak stems and foliage due to poor nutrient absorption.
  • More susceptible to toppling over or snapping.


  • Use root stimulants early in the plant’s life to encourage robust root development.
  • Ensure the pH and nutrient levels in your medium are optimal for cannabis growth.
  • Introduce beneficial microbes that assist in root development.

6. Hot or Cold Root Zone


  • Root growth slows down or ceases.
  • Above-ground plant growth is stunted.
  • Roots appear shriveled or might go into shock, turning dark.


  • Insulate pots from extreme ground temperatures using pot stands or elevating systems.
  • In hydroponic systems, maintain water temps between 68°F to 72°F.
  • Root zone heaters or coolers can assist in maintaining an optimal environment.

7. Fusarium


  • Sudden wilting of leaves and branches.
  • Dark streaks appear on the stem, especially near the soil line.
  • The base of the stem might become soft and mushy.


  • Remove and dispose of affected plants immediately.
  • Sterilize growing equipment and the environment.
  • Use biofungicides and organic compost to suppress fusarium populations.

8. Pythium


  • Young seedlings ‘damp off’ or collapse at the soil line.
  • Older plants exhibit root rot symptoms.
  • Leaves may show signs of nutrient deficiencies.


  • Maintain a sterile growing environment, especially in hydroponic systems.
  • Ensure the growing medium is well-draining.
  • Beneficial microbes, such as Trichoderma, can help keep Pythium at bay.

9. Damping Off


  • Seedlings fall over, appearing pinched at the base.
  • White mold may appear at the base of the seedling.
  • Roots might appear brown and rotted.


  • Avoid overwatering seedlings.
  • Use sterile seed-starting mixes.
  • Ensure good air circulation to prevent mold growth.
Cannabis clone with healthy roots

Ways You Can Boost Root Development

Cannabis Root Stimulators

Microbial products like Amplify are very effective and can give your roots the kickstart they need. Amplify is easy to use and can be implemented at any stage during your grow. If you haven’t tried it, you will find that it significantly improves your cannabis game.


A symbiotic relationship fungus that can improve nutrient uptake.


A fungus that protects against root pathogens.

Flushing The Roots

As a parting tip, always remember the importance of a good flush. Flushing helps remove excess salts and nutrients, giving you a smoother and better-tasting end product.

Learn the complete cannabis flushing process here!

In the game of cannabis cultivation, remember: it’s the roots that hold the secrets to a plant’s health and vitality. Treat them with respect, and they’ll reward you with bountiful harvests.

Cannabis Grow Series

This article is part of the cannabis grow series where we want to teach you how to grow cannabis step-by-step in a simple and effective way. Explore the full series here!

Learn how to spot and fix cannabis nutrient deficiencies

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