What is a root nodule?


A root nodule is a small, specialized structure that appears on the roots of certain plants, particularly those belonging to the Leguminosae family. These nodules are formed as a result of a symbiotic relationship with rhizobia, a type of soil bacteria that invades the plant's root system. In some instances, root nodules can also be found on the roots of potted roses.

The primary function of root nodules is to facilitate the nitrogen fixation process, whereby atmospheric nitrogen is converted into a form that plants can easily assimilate. This process enables Leguminous plants to thrive in soil that is nutrient-poor, thereby increasing their chances of survival and growth.

Succulent root nodules have been the subject of ongoing discussions and controversies. While some believe these nodules are rhizobia that live in symbiosis with plants and feed on a portion of their nutrients, others argue that the nodules are a collection of root nematodes and, therefore, the soil must be treated with pesticides. Regardless of whether rhizobia or root nematodes cause the nodules, it is an issue that can potentially harm and even kill succulents.


What are the symptoms/signs of succulent root nodules?


Succulent root nodules may be challenging to detect in the early stages, as they are often overlooked during planting due to the healthy appearance of the exposed parts above the soil.

If you notice that your succulent plant looks dehydrated, thin, or stretched out, and its growth has slowed down, it may be the root nodules! These nodules prevent succulent roots from absorbing nutrients, forcing the plant to draw on its leaves for nutrients. If you observe these symptoms, inspecting the succulent's root system for nodules would be prudent.

How to distinguish typical root nodules and root nematodes?


Root nodules are commonly located in regions of the root system that are encompassed by soil. The objects have a circular shape, and when cut open, they reveal a white color. However, root nematodes are characterized by their irregular shape and have the propensity to spread to the succulent stem. A pink-colored wound is observed upon incision of a nodule affected by root nematodes.


How to treat succulent root nodules/knot nematodes?


To effectively treat this issue, it is recommended to remove the affected roots and stem areas by using a sterilized blade or garden scissors. This process is known as "beheading" in succulent propagation. Here is the step-by-step guide:

Step 1: Using a sharp tool, carefully remove the heads of the succulents and discard any rotten roots or used soil. 

Step 2: Rinse the remaining head succulents thoroughly and dampen them by spraying them with 75% alcohol. 

Step 3: Allow the succulent heads to heal naturally by placing them in a well-ventilated area for 2-3 days. 

Step 4: Disinfect used flower pots and gardening tools by soaking them in water above 65℃/149℉ for 10 minutes. Knot nematodes can be killed at a high temperature. If it is just the typical root nodules, this will not be harmful to planting accessories. 

Step 5: To ensure healthy growth, use fresh succulent soil to replant the beheaded succulents.


It is advisable to incinerate all soil and root nodules to avoid the risk of secondary infection if the nodules contain nematodes. Although high-temperature sterilization can be used to recycle soil, it is not recommended to apply this method to recycle the root nodules soil.

For grounded succulents, dealing with the root nodules will be a huge project. To eliminate the problem, you need to uproot all the plants from the soil and deeply plow and till the soil to prevent the recurrence of root nodules.

How to prevent succulent root nodules/knot nematodes?


First of all, we need to know why succulents grow root nodules.

1. If you use garden soil that has not been sterilized to plant succulents, the possibility of root nodule infection is higher than that of sterilized nutrient soil.
    2. Frequent use of organic fertilizers that have not been fully decomposed and excessive use of nitrogen fertilizers can easily cause root nodules on potted plants.
      3. Failure to callus the wound after root pruning. Or frequently repot succulents. When the root system has wounds, it often gives opportunities for rhizobia to invade.
        4. Plant succulents together with plants that like to grow nodules.

          You may wonder: How to Fertilize Succulents?

          How to prevent succulent root nodules/knot nematodes?


          1. It is best to check the soil and root system of newly purchased succulents within a month to detect problems early.

          2. Use fresh and "healthy" soil. You can make the soil yourself or purchase it from a reliable supplier. Using the soil mix soon after buying it is recommended to avoid storing it too long. If you prefer to reuse/recycle the soil, ensure to sterilize it before applying it to succulents.

          3. Regular inspection and management of succulent plants. Repot succulents every 1-2 years in the spring season.

          4. Watering succulents with carbendazim dilution in spring can prevent issues in summer.




          It is a rare occurrence for succulents to develop root nodules. However, if such a situation does arise, there is no need for undue concern. While typical root nodules do not pose a significant problem, addressing them promptly is essential for your succulents' healthy and robust growth. If the nodules are determined to be knot nematodes, it is critical to undertake a thorough and meticulous disinfection. Please do not hesitate to save and share this blog with your fellow succulent enthusiasts if you think it is useful. Leave comments if you have other questions about succulents.

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