Home » Learn » How to Harvest and Save Moldy Seeds

How to Harvest and Save Moldy Seeds

If the seed’s outer casing is hard but covered in mold, you can try cleaning the fungus off.

To do so, you need to spread the affected seeds on a tray and mist them with a weak hydrogen peroxide solution. 

Then, leave them to dry.

You can certainly rescue some moldy seeds, but learning how to prevent this problem can eventually save a wagon of time and effort.

Thus, in this article, we will look at how to save moldy seeds and seedlings as well as how to prevent mold from forming. 

Will Moldy Seeds Still Germinate?

The truth is that no one will be able to say for sure whether or not the seed will sprout if you plant it with mold.

The moldy outer layer might dry out, and, if so, the plant will grow completely healthy.

But to increase the seed’s chances of sprouting, it’s better to spare a minute to take care of the little guys that have been affected.

Also, remember that as long as the outer shell is hard and healthy, the mold on the seed probably won’t create a problem as long as you clean it.

However, if the casing is mushy, then the interior of the seed is probably already ‘ill,’ and it won’t be able to germinate.

Do I Have to Clean Moldy Seeds?

It would be best not to introduce any mold or mildew to your potting tray, so cleaning the seeds is extremely important.

To clean your moldy seeds: 

  • Spread all the seeds (even those that don’t appear moldy but have been close to the affected seeds) on a tray.
  • Mist the seeds with a weak solution of either white vinegar, hydrogen peroxide, or rubbing alcohol and water. You should have a 1:10 ratio between your cleaning agent and water. 
  • Ensure you dampen all sides of the seeds.
  • Carefully spread the seeds once again on the tray and leave them in the sun.
  • Very soon, the solution will evaporate from the seeds’ surface. However, it would have had enough time to disinfect the casing and kill the spores.

Or, gently removing the outer casing might help get rid of the mold.

But, keep in mind that not all the seeds will germinate after cleaning, even though disinfection will certainly save at least a few future plants.

Read Also >> How to Harvest and Save Nasturtium Seeds

How Do I Get Rid of Mold on Seedlings?

Mold can also affect your seedling trays that are full of starting soil.

And if it does, it’s best to get rid of this annoying parasite to give your plants the greatest chance of survival. 

To remove mold from your seedling tray:

  1. Get a knife or a spoon and scrape off the mold from the soil.
  2. Throw the mold in the trash. 
  3. Give the tray enough air – either make a few holes in the plastic covers or remove them entirely (this would be beneficial if the seeds have already sprouted).
  4. Mold flourishes in moist and warm places, so if you have a warming pad or any other source of heat near your plants, you should remove it for now.
  5. Finally, give the seedlings some time to dry out – use a fan that will blow across the trays or simply place the seedling trays in a well-ventilated place.

Also, remember that you can reuse soil that had an issue with white mold, as long as you leave it to bake in the sun for an entire day.

Read Also >> How to Harvest and Save Hollyhock Seeds

How to Prevent My Seeds From Becoming Moldy

To prevent moldy seeds: 

  • Run a fan over your seed trays to ensure proper circulation. (Also, the gently blowing fan can help strengthen the little starts.)
  • Water the seeds from the bottom to keep the top of the soil dry.
  • Ideally, you should never let your trays sit in water; anything longer than about 20 minutes in the water is not beneficial.
  • Make sure you don’t overcrowd your tray or pot as this would, once again, reduce airflow.
  • Give your seeds proper sunlight to help prevent mold growth.

How to Properly Dry Seeds to Prevent Mold Growth

You should never store seeds until they are completely dry. 

To completely dry your seeds, you should prepare a paper towel and leave the seeds on it for between 4-7 days.

The seeds should become very hard, to a point where the largest ones snap.

You can then put your dried seeds in a sealed bag or an envelope until next year.

Overall, if you have adequately dried your seeds under the sun and then stored them in a dry, well-ventilated place, they will not develop any mold or mildew.

However, it is always better to have a lot of extra seeds, just in case some do mold. 

Generally, you should save up to five times more seeds than you think you’ll need.

Read Also >> How to Harvest and Save Gerbera Daisy Seeds


Unfortunately, no method will always prevent mold. 

And, sometimes, moldy seeds won’t sprout, and moldy seedlings won’t grow. 

But, you can follow the steps above to try to save your seeds from mold damage.

Table of Contents

Similar Posts