Help! I have mold on my seedlings. Please lord somebody help!

Hello. I have a grow journal over in the grow journals section, but I figured I would try posting here. I have mold on my precious seedlings! Help! Does anyone know what to do?


STOP watering so much. Your plants are damping off from too much moisture. If you do that it will likely rectify itself in time.

Just a light mist on the leaves until fully rooted. You are close and will likely have to transplant in a few days. Keep the soil material dry when you do.


Are you referring to the little white mold spots in the center of the dirt

1 Like

@Myfriendis410 OK well I’ll try that but I grow in hydro rdwc. I can stop watering so much for now but what’s going to happen when I put them into their buckets in a few days?

@bryan No sir it is hard to see in the pic but one of the roots coming from the plug has grey/white mold on it. The plugs also seem to be getting a lighter coating in spots. I’ve also had to cut the dead ends of one of Roxanne’s baby leaves because it had fuzzy white mold growing on it.

That rapid rooter is soaking wet. They should be damp & kept damp, but not dripping wet.


@blackthumbbetty Not so wet- check. If I keep them less damp for a couple of days will the mold problem correct itself? Or is it going to pop back up again later in the grow?

I guess the question is, it is a big deal that there is a potential for mold, or is that normal and it’s only when conditions are less than ideal that it shows up?

@bryan @blackthumbbetty @Myfriendis410

And of course to you all thank you for your ideas and advice. We will get through this thing!


Mold is not a friend to your plants, for sure.

We need a hydro guy to weigh in. My first inclination would be to rinse in peroxide and water but I don’t know what concentration to suggest. I know @TDubWilly has washed roots with straight 3%.

I will say; you had better get tuned up on this because the wheels can come off doing hydro very quickly. From green to brown over night.


Indeed they can. I’ve had good success growing with hydro in the past, the main difference now is that I’ve got decent seeds. Every grow I’ve ever done has been bag seed and i’d just cull them if I needed but this time I’ve got good genetics and I really want to keep them alive.

Some beneficial fungus could help.

What is this thing of which you speak @blackthumbbetty? I have no experience with such things…

Mycorrhiza are your roots best friends. They protect roots from pathogens, as well as helping the soil food web. You can buy any number of powders or liquids containing the beneficial fungi, and apply it directly to the root zone.

Hydrogen peroxide & h20 would probably work, too. However, mycorrhiza will not only help with pathogens, but it will also help your plant eat better & make your plant’s root zone explode with growth, which in turn means bigger, healthier plants.



Mold and Marijuana Plants. How to stop mold From forming.

To prevent marijuana mold growth, maintain the proper temperature and humidity level in the grow room. Watering the plants plays an important role to prevent marijuana mold growth. Do not over-water the cannabis plants. Remove any decaying materials surrounding the plant. If you see any signs of mold growth in the buds or leaves, remove it immediately as soon as detected. If mold is seen in stems and many areas of the plant, remove the whole marijuana plant to prevent spreading of molds in garden. Wear gloves while removing molds. Fungicides can also be applied to the infected plant. The chemicals from this fungicide will prevent the further spreading of molds and its spores. For indoor growing, do not use carpets on the floor. This will give the molds a favorable condition for them to thrive. Always keep the floor dry and clean because molds love to grow in moist and dark areas.

Prevent marijuana mold growth by maintaining the moisture level of the cannabis. Ideal level of moisture is about 10%-15% for the harvested weeds. After harvesting marijuana, allow enough drying time for the buds. Different sizes of buds will require different drying time. Make sure to complete the drying time before putting the buds in jars for storage. Use jars with airtight lids to prevent marijuana mold growth. If there is still a high level of moisture present in the buds the time you put it inside the jars, you are giving the molds a nice place to grow and multiply. During marijuana curing, allow the right airflow by opening the jars every 12-24 hours.

Do not let these molds eat up your cannabis while you are growing, curing, drying or storing them. Prevent marijuana mold growth to produce healthier buds. Preventing mold growth is always better because there is no cure when these molds are already attached to your cannabis plants. Remove the infected parts to stop further growth.

1 Like

Thanks @Myfriendis410

First you need to upload some more pictures @filthyhat because I’ve used rapid rooters lots of times and all I see on your picture is good white roots coming out of it, except at the bottom where water tends to gravitate to, and if it sits stagnate, will cut off oxygen and cause the browning (pythium) that I can see. I don’t see mold. All the roots up higher are white.

Second, go ahead and use some peroxide to kill mold if you think that’s what it is, you won’t hurt the plant with it. I think @kabongster uses something like 5ml/gal of 3% hydrogen peroxide if your gonna mix it with water and water your plants with it but you don’t need to water at all so I would just “spritz” the roots coming out of the rooter with straight 3% peroxide a couple times or more a day.

Third, you do look a little heavy when it comes to watering. And it looks like the plants are suffering because of it

Hard to really diagnose something off of one picture so that’s the most descriptive I could be based off what i see. I also didn’t see any pH numbers so make sure your pH is at 6 or below right now


for the babies roots and delicate root hairs, I’d mix 5-10ml 3% Hydrogen Peroxide/gallon of water and use what’s necessary for watering, maybe put a few clay balls under the rooting blocks to keep them out of sitting water.

just checking, do you have a thermostat on the heating pad to keep it from overheating?

the bubbling water from the air stones cause water to splash on the clay balls the plant is placed in and the water will wick up to the roots without soaking the grow cube.

the mycorrizhae mentioned is a beneficial fungus that will colonize the roots helping them grow big and healthy and the will crowd out bad stuff. I like