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white stuff on cannabis seeds

How To Get Rid Of White Mold On Seed Starting Soil

I love starting seeds indoors, it opens up a huge world of plants that you can’t find in a local garden center.

But it’s easy to become frustrated too, right?

But remember that seedlings are simply baby plants and they need a little more care than when they have grown up.

And a little extra work now is so worth it later when your harvest starts.

One of the most common seed starting problems is white, fluffy mold that starts to grow on the top of your seed starting row.

Does Mold In Plant Soil Hurt Seedlings?

It’s commonly thought that fuzzy white mold growing in your soil will kill seedlings but this fungus really isn’t harmful to plants.

But if you are finding mold growth happening around your seedlings then that’s a sign that conditions are right for damping off disease.

That’s a nasty problem you don’t want to have!

Damping off is caused by a type of fungus that causes your plants to pinch off and fall over quickly. But you can learn how to treat and prevent damping off.

What Causes White Mold In Seed Trays

But even though white mold is pretty harmless to plants it sure doesn’t look nice, does it? I know I don’t want mold growing in my home and I bet you don’t want it either!

It’s also a sign that something is wrong with your seed starting setup and it needs to be fixed quickly to keep your seedlings healthy.

The main causes of white mold on seed starting soil are overwatering, overcrowded seedlings, keeping them to warm and a lack of airflow.

How To Get Rid Of White Mold On Seed Starting Soil

The good news is these problems are all easily solved!

You don’t need to buy any harsh chemical sprays either, just use these simple tips to get rid of mold on your soil.

Step 1. Remove The Mold

Ok, this step is optional but it will speed things up a little bit. If you don’t want to remove the mold it’s ok because it will naturally die with the rest of the treatment.

Take a small object like a popsicle stick, pencil, or knife and gently scrape off as much of the mold from the soil as you can. Wipe it onto a paper towel or newspaper to dispose of.

You don’t have to get it all, but it does quickly make the soil look much nicer.

Step 2. Add Ventilation

If the lids are still on your seedling trays this can be a big cause of mold growth.

I always remove the lids after the seeds have sprouted as the extra humidity is really only needed during the germination stage.

If you feel that you need to keep them on because the seeds haven’t sprouted yet then try proving them open for a few hours each day to let some air in.

Simply use a long popsicle stick or twig to hold open one end of the plastic dome.

Step 3. Lower The Heat

Keeping the soil to warm can encourage mold growth and hurt your seedlings.

So while heat mats are really helpful during the germination stage, make sure to turn them off after the seedlings have started to grow.

Step 4. Proper Watering

Never let your soil become soggy or let water sit in the tray.

You do want the soil to stay consistently moist but make sure you let the top of the seed starting mix dry out before you water again.

Step 5. Natural Fungicide

Years ago I started using natural fungicides to help prevent mold and other problems in my seedlings.

The added benefit of using these is that it can be done at the same time you would water your seedlings.

There are two simple recipes that I use with great results.

The first is to use a mixture of hydrogen peroxided and water, instead of plain water when I water my seedlings.

To make this simply mix 1 teaspoon of 3% peroxide to 1 cup of water and use this to bottom water the seedlings with.

I’ve found this is a great mold preventative in our seed starting.

If you already have a mold problem or root rot then you can increase the peroxide to 1 tablespoon per 1 cup of water for treatment.

Once it’s been cleared up go back to the lower dosage.

It’s important to remember that hydrogen peroxide can harm the leaves of plants if the mixture is too strong.

Because of this, I prefer to bottom water only if using this method. Always test new treatments on a small sampling of plants to make sure you like the results.

Another natural fungicide that is easy to make is mixing 1 tablespoon of baking soda with 1 gallon of water. Then use this to water your plants.

It also works very well as a foliage spray if you have mold growing on the leaves or stems of plants. However, I don’t recommend using this mixture until after the seeds have sprouted and grown up a bit.

Prevent Mold

Use Soilless Seed Starter

One of the easiest ways to cause a mold problem with your seedlings is using a seed starter mix that has organic matter like compost or soil.

While these are both wonderful things for plants to grow in when you separate organic matter from the ground it comes out of balance with nature.

Often bagged soil mixes contain bacteria and mold spores that can start growing in your seed trays with nothing to fight it off.

Instead, use a soilless seed starting mix for starting seeds and young seedlings.

Then once they are growing well you can transplant them into larger pots with a richer compost mix.

Use Non-Organic Pots

Using natural plant pots like peat pots, coconut fiber, or even newspaper pots can seem like a good idea.

After all, we all like to use natural biodegradable products or reuse something that would go to waste.

But these types of pots are not always the best for young plants to grow in. They can stay wet for a long time and cause mold to start growing on the pot and soil.

If you find that mold is a common problem when you are starting seeds then try using plastic cell packs and pots.

If you buy good quality ones they can last for years, we have many that have been used throughout the growing season for 5 years or more.

Don’t Over Water

Avoid overwatering your seedlings, many new gardeners don’t realize that one of the main things that can kill your seedlings is overwatering.

Not only can it lead to mold growth but also to root rot and damping off disease.

Let the top of the soil dry out before watering again. Then water the seedlings well and drain off any water that remains in the seed tray after 30 minutes.

Use an organic fungicide when you water to help discourage mold growth as well.

Increase Air Flow

One of the easiest things you can do to help prevent mold growth on your seedlings is to increase air circulation.

The easiest way to do this is to set up a fan on low that can blow air through your plants.

This will help to dry the soil surface but also strengthen the stems of the seedlings too. You don’t have to leave the fan on all day.

The simplest way would be to set a timer to have it come on for about an hour or so each day.

Remember to also give space between plants under your light set so that the air can move freely through them.

Disinfect Your Seed Trays And Pots

Mold spores and plant diseases can often lay dormant in seedling trays.

To make sure your plants get the best start possible it’s always a good idea to properly clean and disinfect your seed starting trays before using them again.

Start Seeds Outdoors

I’ve always found that starting seeds indoors has more problems than when we started seeds outside or in our greenhouse.

Indoor conditions are just perfect for mold growth on wet soil. So if possible you can make things easier by starting seeds in a cold frame or greenhouse.

But don’t worry if you don’t have an outdoor growing space. Just use these tips to grow healthy seedlings indoors.

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Kim Mills is a homeschooling mom of 6 and lives on an urban homestead in Ontario, Canada. Blogging at Homestead Acres she enjoys sharing tips to help you save money, grow and preserve your own food.

White Fuzzy Stuff On Your Cannabis? Here’s What To Do

Growing cannabis comes with so many things to worry about such as lighting, nutrients, increasing yields, and so much more. Many growers don’t even think about mold growing on their cannabis plants.

However, mold can cause many serious health risks. If you notice your cannabis may have mold on it, you should never consume it.

While consuming cannabis that has mold on it most likely wont cause serious harm to someone with a healthy immune system, it can cause severe harm to those with compromised immune systems. Individuals who consume cannabis with mold may experience coughing, nausea, vomiting, headaches, or even more serious conditions such as aspergilloma , which is basically a clump of mold growing inside the body.

Cannabis can start to develop mold in the growing process, and after it was harvested if it was not properly dried/ stored.

No need to worry though, keep reading to learn how to identify mold on your cannabis, and how to reduce the chance of mold appearing.

Video: What to Do With Moldy Weed

Does Cannabis Go Bad?

Weed, like any plant or herb, can grow mold. If you see white stuff on your weed, it’s mold. That means the weed itself has developed mold and there is no way to remove it and still smoke it. You will have to toss it out and try again.

Mold can be several different colors, from white, off white, yellow, grey, and even orange.

Other than situations such as mold growth your weed shouldn’t go bad. So long as it’s properly stored just like all other herbs are vegetables in your kitchen, it will be fine. Like other herbs, the cells will break down and they will oxidize which simply means that the cannabis is less potent over time. So long as there aren’t mold spores on it, old weed won’t kill you.

Different Types Of Mold On Cannabis

A few different types of mold can grow on your cannabis plants, all being equally dangerous for someone to consume. Interestingly enough, mold can develop on your cannabis plant at any stage of growth. However, mold is most likely to grow 2 weeks before harvest.

Imagine how devastating it would be to go through the months of growing just for your hard work to go to waste? We will look at the most common types of mold to grow on a cannabis plant, how to identify it and how to reduce the chance of it growing. Unfortunately, once mold has started growing, your plant is a lost cause, there is no treatment.

Mold is also more common on certain strains, so it’s always recommended to do your research when choosing what strain to grow.

White Powdery Mildew

This type of mold shows up in hot, humid, stagnant air. Often it will grow on the large fan leaves of your cannabis plant, as there isn’t much airflow between the leaves. White powdery mildew can also grow on the stem of your plant, so it’s important to check the entire plant!

It can also be common in enclosed spaces such as a grow tent. Make sure to inspect your plants often. You can reduce the risk of white powdery mildew by placing a fan in your grow tent, this will help with air circulation. No need to worry about adding a fan to your Grobo, it’s included!

White powdery mildew looks like someone poured flour on your plant. It’s usually a dull white and looks powdery. It can sometimes be mistaken for trichomes when on cannabis flower. An easy way to tell is to shine a light on the cannabis bud. Trichomes will twinkle in the light, like tiny crystals… whereas white powdery mildew will just look dull.

Luckily if you see this mildew growing on your plant, you can treat it. We recommend pulling off any severely infected parts if your plant.

Next, you c an use a fungicide, such as this one . It works on a wide range of fungal issues, so it may have more than one use.

A more natural way to kill off white powdery mildew is to use neem oil . Neem oil is extracted from a plant native to India, and is very effective at stopping the spread of fungus, and also deters insect pests!

There are also several homemade fungicides that work surprisingly well:

Combining baking soda and liquid soap, and a bit of water in a spray bottle works well as a fungicide. While dish soap can work in a pinch, it’s best to get castille soap for this DIY. Using a peppermint scented castille soap is beneficial as the scent will deter pests, however if you are sensitive to the scent of peppermint, unscented will work as well.

Shockily enough, mixing 1 part mouthwash and 3 parts water in a spray bottle will kill off the mildew. We always recommend testing out this method on a small spot on the plant before spraying the entire plant, as it may cause damage.

spraying water on your plant can be a quick fix. White powdery mildew is one of the few fungi’s that do not spread by water, in fact; it makes it much harder for the mildew to grow. When in a pinch, spraying you plant down with water will make you plant less of an ideal environment for this mildew to grow, which can help stop the spread. It’s best to use another treatment, as this one will simply reduce the spread.

The images below show what white powdery mildew looks like on a cannabis plant:

Bud Rot

The scientific name of bud rot is botrytis cinerea. This mold is typically greyish brown in color. Bud rot thrives in cooler humid environments. In order for bud rot to grow, spores must be present. They can be spread through air, clothing, and water. This is one of the reasons why sterilizing your pruning equipment in-between each cut is so important.

In order to reduce the chances of bud rot, follow these few steps:

1. Growing indoors significantly reduces the chance of bud rot. Make sure not to wear any potentially infected clothing, and wash your hands prior to handling the plant

2. Always sterilize any equipment used on your cannabis plants

3. Keep an eye on the humidity and temperature. Bud rot will have a harder time developing in warmer, drier conditions.

4. Keep an eye on dense colas . As there is less airflow, this is another ideal location for bud rot to develop. If you notice bud rot, cut the infected part of the plant off immediately and make sure it does not touch any other part of the plant. Bud rot can spread very fast, so do not delay removing potentially infected branches.

Below are a few images of what bud rot looks like. Bud rot typically makes the buds easily fall apart when touched.

White Fluffy Mold

This type of mold may be caused by a variety of mold species, such as aspergillus, cladosporium, and penicillum. As most of us do not have access to a lab that can test the type of mold, these ones fall under the same category, as they look similar and grow in the same conditions. This mold is commonly white, but may also be shades of grey, green, black, and yellow.

This mold most often appears after the plant has been harvested, during the drying process. If cannabis is not dried properly, it will have excess moisture, which is the ideal environment for white fluffy mold to grow. Learning how to properly dry. Store your cannabis is the best way to prevent this issue.

Before we move on to how to properly store your cannabis, here is what white fuzzy mold looks like on cannabis:

Properly Storing Your Weed

The best way to avoid the issue of white spots or any other colored spots on your weed is to properly stored in first place.

The best containers to use are glass or ceramic. The reason for this is to guarantee that you have an airtight container so that other smells and flavors don’t get transferred to your weed.

You can store your container in a cool, dark place but of course make sure the weed is not wet at all. To that end if you’re using a recently washed container be sure it’s allowed to dry 100% before you place your cannabis in there. Even an incredibly small amount of water left inside the container when sealed up will create an environment conducive to mold growth.

Having a cool, dark place is important because fresh weed is rich in THC, and CBD but if you expose it to direct sunlight the THC will start to break down into a cannabinoid called CBN which is significantly less potent. That said if it’s exposed to sunlight or any other type of ultraviolet light overtime it will break down and this conversion process will happen but it won’t kill you. It certainly won’t make you sick if the worst that happened to your weed is that the THC has broken down into CBN. However, it won’t have the richness in flavor in the potency that it did originally.

If you store it in something like a ziplock bag just leave it around your house, it might not be something you want to smoke down the line.

A mason jar is a wonderful way to store your weed. They can be kept in a cool place just as with herbs, for more than six months so long as they’re stored properly. But if you placed your weed in a mason jar for just two days and it’s already developed white stuff on it, your jar was far too wet and it’s mold.

Check on Older Cannabis

Thankfully, if you have stored cannabis and are worried about any unwanted developments, literally and figuratively, there are ways that you can check.

If you’ve been storing your weed for a long time, It’s important to give it a quick check before you open it and smoke it.

1. If the leaves have dried out and they’re powdery, it won’t be enjoyable.

2. If there are any fuzzy white powdery spots growing on it, it’s moldy and you absolutely should not smoke it.

If you do have moldy cannabis, while it is not safe to smoke, you can use it to make cannabis honey or cherry oil. Between the decarboxylation process and the use of isopropyl or ethanol, the mold spores will be killed making it safe to consume. If you are interested in learning how to make honey or cherry oil, check out our video on it!

You also want to pull the weed apart in your hands and listen for that crackling sound. If you hear it snap your weed might be too dry. If there’s no noise whatsoever it’s too moist and might very well have developed mold. So if you pull apart your weed and you hear nothing, you might want to consider purchasing new weed.

Aside from the visual cues your weed might give you, if you open up your mason jar you should get a good whiff. If the weed smells very musty, somewhat like an old locker room, it’s probably moldy so just because you can’t see the white spots doesn’t mean the mold isn’t forming. If it smells like plastic, it was poorly stored or contaminated.

Essentially, when you open your weed no matter how long it’s been in storage, it should still smell like cannabis. The older it is, the less intense the smell will be but the smell itself shouldn’t have changed to something else. If it does smell like anything else other than the weed smell you had when you first bought it, something’s probably wrong.

If it doesn’t smell and you don’t see any visual signs of mold, you should be in the clear but if anything at all is slightly off-kilter, smoking weed with mold on it can cause serious ramifications and should be avoided at all costs. So, check for visual signs of any mold development, smell it, feel it, and listen to it before you decide to smoke it. And if your stash has white stuff on it after 2 days, try a different method of storage.

Do you have any amazing tips for storing cannabis? Let us know in the comments below!

Are you interested in growing you own cannabis? Check out

Grobo is an automated grow box designed to make growing easy. Grobo also carries lots of grow accessories to help you grow cannabis stress-free, even if you don’t own a Grobo just yet. Check out our Co2 Booster, which helps maximize yields in a Grobo or grow tent!

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