How To Get Rid of Mold In Seedling Soil

It’s discouraging when mold appears on your carefully nurtured seedlings. Mold growth on pot, seedlings, or seed starter trays is a typical problem that can be frustrating to deal with. You will inevitably encounter this, no matter how skilled you are.

The most effective strategy is to identify the problem at its earliest stages so that you can stop it in its tracks. In this article, you will discover how to eliminate mold from growing seeds and young plants.

Why are my seedlings molding?

Mold, as is well known, grows best in a warm, moist setting. That’s the ideal environment for numerous seeds to germinate!

If you don’t take proper precautions, the seed trays you use can quickly become the ideal environment for the growth of several kinds of mold, including orange, green, or white.

It can be quite alarming when you first notice your seedlings are moldy. But don’t worry; minor adjustments can easily remedy the issue.

Getting rid of mold in seedling soil

It is simple to eradicate the mold germinating in the seedling trays. Additionally, you do not have to purchase any chemical powders or sprays.

Here are the steps to follow:

Remove the mold

The first step is carefully removing the mold from the soil’s surface.

If can’t bring yourself to remove every last piece of dirt, that’s okay. The rest will die out once you’ve finished the remaining steps. Scrubbing it off with a scraper merely speeds up the process.

Aerate the flats

If the lids are still on your trays or flats, this is definitely part of the problem. Leaving the lids on the flats or trays is a surefire sign that you have a storage issue.

Get some air into the trays by propping open one end with a pencil or something similar. You can take the container apart at its seams when all the seeds have sprouted.

Give the soil a little time to dry out

Be careful not to overwater your plants. After 30 minutes, remove any standing water to prevent the soil from becoming waterlogged.

Keep the soil equally moist, letting the top few inches dry between waterings. However, you should never let it dry out entirely.

Mold growth is simply the beginning of the problems resulting from seedlings’ chronic overwatering.

Ensure you’re not giving them too much water by checking the level before you water them. In this case, even a cheap moisture gauge will come in handy.

Switch off the bottom heat

Turn off the heating mat once all the seeds have grown. Mold will flourish in warm conditions, which might be bad for the seedlings.

Why is there mold on my soil when I start seeds?

  • Over-watering or poor drainage

The same is true for your soil’s poor drainage. Spores produced by fungi can travel in the slightest breeze and often settle in nearby area. But if the conditions aren’t right for them, such as a lack of moisture, they won’t be able to multiply and eventually form mold.

  • Insufficient Sunlight

If you don’t give your houseplants access to natural light, they won’t get the full benefit of photosynthesis, which is how they gain nutrients. Lack of sunlight contributes to the damp, dark environment in which mold thrives.

  • Organic fertilizers

The likelihood of noticing the white mold on top of the soil increases if you add organic fertilizer right before you plant or after you have already planted.

Fertilizer from a substance like PittMoss or from an electric composter are typical suspects for feeding the soil’s existing bacteria.

The powerful biomatter you mixed into the soil is still decaying and gives the nutrients the bacteria (and the soil) need to flourish.

  • Inadequate aeration

There may be a number of causes for mold growth. The anaerobic (oxygen-free) environment is ideal for actinomycetes.

In the presence of white mold on soil, anaerobic conditions (not enough air circulation) may exist, providing an ideal environment for actinomycetes.

Will seeds still grow if they get moldy?

Moldy seeds are usually not recommended for planting. This is because they may row into unhealthy plants or not germinate. These seeds could be infected with bacteria or fungi that prevent germination or spread to the growing plant.

Seeds that have been damaged by mold are unlikely to germinate. In addition, several species of mold can release toxins that kill seeds before they sprout.

If the mold contamination is too great, the seeds may not be able to survive the poisons and grow into healthy plants.

Seeds showing signs of mold should be discarded and replaced with fresh, mold-free seeds. This will give your seedlings the best possible start, and if you do decide to use the seeds, you can readily check their viability before planting.

Does white mold hurt seedlings?

When germinating seeds, white mold is an all-too-common problem. Most seedlings require a warm, humid environment, which is also ideal for mold growth. But if white mold is present, the seedlings are doomed.

Seedlings are able to recover from mild cases of white mold as long as the mold is eradicated quickly. If nothing is done to improve the seedlings’ habitat after detecting the mold, the seedlings will certainly perish.

Damping is caused by mold on seedlings. Damping off is characterized by white, fluffy mold on the seedling, soft, weak stems, and stained, wilted leaves.

Seedlings that show damping-off signs are not likely to survive. It’s preferable to start over with new seeds and see if changing the conditions of the growing area helps prevent the problem from recurring.

Although white mold on seedlings is worrying, it is usually treatable by altering the surrounding conditions. Mold thrives in wet, dark places, so don’t keep the seedlings in a moist area without allowing them to dry out.

You may prevent future problems with white mold by making a few straightforward adjustments to your seedling setup.

Remove mold from seed trays

If you install one in the room, ensure the fan is set to a very low speed. Young seedlings are susceptible to damage from the wind.

The soil should be moist, never waterlogged, when planting seeds. Keep in mind that you should constantly water the tray’s base. However, the white, fuzzy mold on the soil’s surface may hinder the seeds’ germination ability.

Scratching the soil lightly with a fork may help get rid of it. If the seeds have already begun to germinate, proceed with extreme caution.

Can bagged soil get moldy?

Mold can grow in bagged soil if it isn’t kept dry. If the bagged soil gets wet, mold will grow. Make sure the bagged soil is dry before putting it in a sealed plastic container or a garbage bag without any added fragrance to avoid this.

How to clear mold in seed soil bag

  • Use only a tiny amount of the recommended fungicides

High-quality fungicides are safe for plants. However, subpar fungicides can introduce soil contaminants that eventually harm plants. Moldy bagged soil is easy to treat with the required fungicides, and you can use it whenever it is ready.

Fungicides are effective in a well-ventilated outdoor area. You can stop new mold growth by using a fungicide.

  • Place it in direct sunlight by taking it outside.

When the bagged soil has fungus, taking it outdoors is a safe and effective natural cure. Mold in bagged soil can be quickly eradicated when the weather is warm and the sun is shining.

Molds require high humidity to survive and will perish in dry conditions. To eliminate mold growth during the dark winter months, artificial lighting is ideal in place of natural light.

  • Ventilate the bagged soil

This is an extremely easy and quick solution. If you find mold in the bagged soil, the first step is to remove any mold spores you can see physically.

After removing the apparent mold, aerate the soil in a dry, non-humid setting (ideally outdoors).

Keep the bagged soil completely dry and away from any moisture sources. Furthermore, some mold spores may be dangerous, so take care not to breathe them in.

Does mold affect seed germination?

It is essential to prevent mold from attacking your seedlings and causing them to wilt and die.


In the end, it comes down to making conditions suitable for seedling growth. If you follow the advice above, you’ll have a far higher chance of cultivating the lush vegetation and colorful flowers you had hoped for year-round.