damping off cannabis

How To Spot And Prevent Damping-Off

Damping-off is a common plant disease that can affect newly sprouted seeds, seedlings, and cuttings. Since the disease appears very early in your marijuana plant’s life, they won’t be able to recover. Learn what causes damping-off, as well as how to spot it and prevent it from happening to you.


You just got new seeds and are looking forward to starting a new grow. After you put your seed in a cup or Jiffy pellet, you watch excitedly as it comes to life; the seed cracks its shell and is now making its way upward towards the light. You watch as the tiny seedling unfolds its first set of tiny leaves. So far, everything is looking great. A few days later, as you check on your new green friend, you find that it has drooped over. Frantically, you try to revive it, maybe by watering some more or administering some of those “special nutrients” – but no dice. Unexpectedly, your seedling has died and you’re stumped. How could this have happened?


Damping-off is a common disease that can affect sprouting seeds, seedlings, or cuttings. It can be caused by several types of fungi, namely Pythium, Botrytis, and Fusarium. Pythium is most common. Although fungus is the main reason for damping-off, the disease is normally the result of several conditional factors.

Sometimes, the fungus can already be present in the growing medium or substrate that you use for germinating. This can happen when your substrate is not sterile.

The second factor can be that the substrate has been wet for too long, most likely from overwatering or due to poor drainage qualities.

Lastly, another factor that can contribute to damping-off is excessive humidity in your growing environment, most-often paired with a lack of adequate air circulation.

Each of these factors by itself or in combination increases the risk for damping-off. Once the conditions for the fungus to grow are optimal, the disease will normally attack your plants at the bottom of the stem, just above the soil line. The fungus will weaken the stem, cut-off the fluid circulation of your seedling, and ultimately kill it.


Unfortunately, damping-off can happen very quickly. Many times, a seedling can go from looking healthy to dropping dead in just one single day. When this happens, it is already too late to do anything since the fungus has already infected your plant and there is no method of recovery. However, you can learn to spot the signs of damping-off in order to prevent it from happening again.

Among the signs of damping-off include small white spots at the lowest part of the stem, just above the soil line. In this same area, the stem will look weak and thin, featuring a darker colour. If you spot these signs and the seedling is still upright, it is only a matter of hours until it will tip over.

Tip: Fungus gnats, which are tiny, dark, mosquito-like gnats, often appear when moisture and humidity levels are too high. Do not worry so much about getting rid of the gnats, but see them as a sign that something is off with the moisture content in your growing environment. The gnats will disappear on their own when moisture levels in the soil return to normal.


When a seedling has already toppled-over from damping-off, there is nothing you can do to recover it. The best you can do is quickly remove the affected seedling together with its cup to prevent the spread of disease to other seedlings.

When one seedling has already died from damping-off, chances are that your other seedlings are affected too, even if they’re still standing upright. One emergency measure you can try to stop the fungus from spreading is applying hydrogen peroxide. Sprinkle about 1ml (20 drops) of 3% strength peroxide onto the soil of each of your seedlings. The peroxide will kill the fungus. Obviously, there is no guarantee this will save your seedlings, especially if the disease has already progressed quite far. What’s most important is that you know how to prevent this occurrence from happening in the future.



Excess moisture from overwatering or high humidity are normally the culprits of damping-off. Check your substrate often to observe if the moisture levels are adequate. Avoid too-frequent watering and make sure that your pots or plastic cups allow for fast and easy drainage. If you use a greenhouse or grow-tent with a cover for cuttings, ensure there is a vent on top that allows for proper ventilation. If there is no vent, remove the cover regularly. Always keep in mind that warm and humid means an increased risk of fungus and damping-off.


For germinating seeds, only use sterile growing mediums. Jiffy pellets, rockwool, or perlite work best. Do not use soils from questionable sources, do not re-use old potting mixes, and do not grow in dirt.

Damping-off is a common disease that can attack seedlings and cuttings. Learn all about damping-off, including how to spot and prevent it from occurring.

Damping of can it recover? by 420monster

Well-Known Member

The Experiment

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.

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.

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.

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.

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.
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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

Credit for article above:
Robert Bergman ILGM

What this is not :

So shortly after my seedlings have sprouted I took notice that 2/5 have fallen over on themselves. The stem looked pinched; in this moment I did not immediately recognize it as damping off since I have been fortunate enough to never of had to deal with it before. So, I propped them up and went on with my day; by the next day it was very clear, as 2 more went down and one was covered half way up with a white fuzz. All the stems were brown and thinned to the point they were flat; almost like a chewed straw and lifeless. It was at this point I knew beyond a reasonable doubt what had happened. A quick search verified my suspicions; so as I got ready to scrap the effected plants and sterilized the entire room with bleach I remembered that the Neem in the cabinet was not just a organic pesticide but also a fungicide. At the rate of losing them either way I decided to experiment to further my own knowledge into the cannabis plants; not expecting very much other then dead seedlings but it seems like it has started to take a interesting turn. I have decided to not only continue the experiment but document it and share it for any one else who might have wondered for themselves for it seems like they may or may not be starting to make a recovery from basically the dead.

The Experiment For the first time in all my years of growing i have been affected by damping off i had a tainted bag of soil that i did not sterilize most… ]]>