Damping Off Marijuana Seedlings

Damping off is a sort of reaction that your marijuana plant has to a disease. It most commonly occurs when roots, seeds, or seedlings undergo an attack from fungi that formed in soil.

This attack stops the upward movement of nutrients, making your marijuana plant is not receiving a proper distribution of nutrients. Because of this unequal distribution, the stem develops portions that are soft and mushy, making the plant eventually topple over and die.

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    Fungi (such as Rhizoctonia and Pythium) grow best in moist, warm soil that has a high concentration of nitrogen. Pythium creates spores, but Rhizoctonia do not – instead, they are parasitic pathogens that are asexual and cause disease in plants.

    Damping off typically starts right under the soil line. As a grower, you probably won’t even notice a problem until you see atrophy in the stalk and lower leaves of your marijuana plant. You will also notice discoloration of the section of the stalk that is closest to the base. This discoloration usually takes the form of a yellow or brownish color.

    You will also start to see lesions between the nodes, which will darken into red-brown cankers. After a while, the entire stem will become soft and brown, and the plant will collapse. This can kill off the marijuana plant since it needs nutrition to stay standing up sturdily.

    Like many problems, damping off will affect young, tender seedlings before it gets to your mature plants. It will first resemble an overwatering problem because of wilting, but you will know it’s a reaction to fungi once you start seeing lesions on the upper section of the plant.

    Not sure if your marijuana plants suffer from a damping off infection? Check the article Marijuana diseases for a list with pictures of all possible marijuana diseases.

    How to fix the problem

    As with most conditions that can affect your marijuana plants, proactive prevention is the best way to go. Keeping close control of moisture levels is the best way to avoid damping off from ever becoming a problem. If your soil is wet, your plant will have “wet feet,” which can eventually ruin your marijuana garden. Don’t water your plants unless the top layer of soil is dry.

    If you live in a place with frequent rains (or it happens to be a particularly rainy year), you can prevent the soil from becoming saturated with water by ensuring that the soil drains well. This will keep water from pooling where the roots are located. When preparing your soil, you can begin by putting in perlite or vermiculite with your soil mix. This will allow for more airflow.

    How to fix the problem - ensure the soil drains well

    If you are growing your crop all the way from seed, you should be extra careful about where those seeds come from. They need to be completely free of disease. Don’t plant them too low – about one-fourth of an inch deep should be good. This helps with damping out because moisture is present in higher amounts the lower underground you go.

    It’s a good idea to also start growing your seedlings indoors, or in containers of some sort. Then, at least one week before you transplant the plants to an outdoor grow site, combine cured compost (which has beneficial bacteria) with the soil. Don’t transplant the seedlings until they have grown at least a few sets of leaves. This will ensure they will be strong enough to handle the transplant.

    Transplant seedlings until they have a few leaves
    Transplant seedlings only when they have grown a few leaves

    If you want to be extra careful about avoiding damping off, spray the soil with an anti-fungal treatment made from copper, chamomile tea, or garlic oil. Let it dry. Additionally, ensure that all your tools are disease-free by sterilizing them after each use. This will help prevent the spreading of any fungi or diseases that have found their way to one of your plants.

    If you do have seedlings that are exhibiting signs of damping off, you probably won’t be able to save them. More mature plants do have a chance of being saved, however. Try removing the parts of the plant that have been affected, and then use diluted hydrogen peroxide to apply to the wounds. If the cankers that appeared on the stems are particularly severe, try spraying them with copper fungicide, clove oil, coriander oil, or sesame oil.

    Marijuana plant symptoms

    Plant symptoms:

    • Atrophy in stalk
    • Stem discoloration (yellow-brown) near base
    • Stem lesions (between nodes)
    • Red-brown cankers between nodes
    • Stem browning and softening
    • Plant falling over
    • Plant death
    • Lesions on upper portion of plant
    • Wilting

    Leaf symptoms:

    • Atrophy in lower leaves
    • Wilting

    The best way to avoid damping off is dedicating the time and effort to giving your plants a strong basis for healthy growth. Pay attention to moisture, nutrients, sunlight, and every other element to makes sure they are able to reach a mature age without succumbing to damping off.

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    FAQs About Damping off Cannabis Seedlings

    What are some common signs of marijuana seedlings that are damping off?

    Among the most common signs of damping off are browning and softening of stems, lesions, and wilting of leaves.

    How do you fix damping off seedlings on weed?

    Controlling moisture levels, making sure your seeds are free of diseases, and spraying the soil with anti-fungal treatment are some ways to treat damping off weed seedlings.

    Have you dealt with marijuana seedlings that are damping off? Please leave comments or questions below!

    Happy growing!


    Avatar for Robert Bergman

    Robert Bergman

    Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]


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