How to Prevent Mold from Growing When Saving Seeds: Fermentation

Fermentation Saving Seed

How to Prevent Mold from Growing When Saving Seeds: Fermentation

I’m sure you’ve tried to save seeds from some of your favorite tomatoes, melons, or squashes. Perhaps you decide to look back on your home grown seed stash only to find that MOLD has taken over, probably destroying your seeds! This will feel rather devastating; especially if you don’t have additional fruits to save seeds from.

If you want to prevent mold from gathering on your seeds, you must ensure that the mold does NOT have access to two of the things it requires most: moisture and food. This seems simple, especially if your seeds SEEM dry and “cleaned”. But even the best rinses and washes will still leave behind enough pulp or sugars for mold to feed on. Instead, the seeds need some time to ferment.

Preparing Squash, Melon, Cucumber, and Tomato Seeds (and More!) for Fermentation

Before you can ferment the seeds, there are a few important things you must do. First, you will need to gather the amount of fruits necessary to save the seeds that you need. If you need 100 tomato seeds, for example, you will need 3 to 10 tomatoes depending on the variety. Carefully remove the seeds from the fruits without damaging them. Damaged seeds have a higher risk of causing an outbreak of mold during storage. Discard of these seeds during the removal process, as they probably won’t sprout come springtime anyways.

Once your seeds have been removed from the fruit and separated from one another, give them a good wash under running water. You want to remove as much pulp or fruit as possible; however, do save some juice for the fermentation process if you have any left. Make sure that all seeds appear to be healthy and of decent size, with no visible cracks or splits. Gather them all into a bowl, and scope out a warm place in your house for the seeds to ferment. Make sure the bowl will not be accessible to pets or children, as there WILL be mold growth during the fermentation process.

How to Ferment Seeds for Long Term Seed Bank Storage

With your clean seeds in a bowl and your warm fermentation spot ready, it’s time to get the party started! Put enough water in the bowl to cover the seeds at least 3 fold. If you have an inch of seeds, I’d recommend 3 inches of water. Allow the bowl to sit, uncovered, in your warm spot for 4 days. Once a nice, gross layer of mold forms on top of the water, check to see if the seeds have sunk to the bottom of the bowl. If they have, begin to pour off the fermentation water and rinse the seeds until no mold is left behind. Bad seeds tend to float, so you might want to get rid of those seeds too.

Drying Seeds After Fermentation: Sealing the Deal

Once the seeds are rinsed clean, they must be dried thoroughly in order to store well. Lay them in a single layer on a paper towel and dry them for several days. I would dry them for between 4 and 7 days, depending on the conditions under which they are being dried. Once seeds are brittle and hard (larger seeds will snap, for example), you can put them into an envelope or sealed bag to store until next spring, or you can add them to your long term seed bank. I definitely recommend saving at least 3x to 5x as much seed as you think you’ll need; it never hurts to have extra, especially in the case of an emergency. In addition, if you lost your entire crop, you would still have leftover seed to use for the following year. Seeds become more and more expensive every year; who wants to pay for more seeds when we can just save them ourselves?