Always Ferment Your Garden Seeds (The Ones from Fleshy Fruits!)
Always Ferment Your Garden Seeds (The Ones from Fleshy Fruits!)
You dried some seeds to put them away for next year, thinking that you've got plenty of great, healthy seeds to get the garden off to a great start the following year. To your horror, you find a bag full of moldy seeds when you pull your seeds out to plant in the spring. Not the experience you're looking to have at the start of the growing season!
When it comes to tomatoes, squash, watermelon, or other fleshy fruits and vegetables with a sugar content, I ferment them. I have had a moldy seed incident myself, so I will always ferment seeds from here on out. Not to mention, the seeds look and feel cleaner. Did I mention that seeds that aren't fermented can be a bigger draw when it comes to pests? The last thing you want is a sheltering field mouse discovering your seed collection!
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| Always ferment seeds from fleshy fruits to prevent mold, pests, disease, odor, and debris. You'll be left with clean seed that looks like it came from a packet! |
Not All Seeds Need to be Fermented: Which Ones Don't?
The seeds that are most at risk of molding typically come from fruits and vegetables. The ones that aren't at high risk are most flowers and herbs. Now, any seed can mold if you try to store them with a high moisture content; so, you always have to make sure seeds are completely dry before storing them. This is very, very important.
Most cut flowers/wildflowers and herbs do not produce fruits for their seeds. Most will produce a fibrous seed pod. Some seeds are simply attached to the petals (like zinnias.) These seeds simply need to be dried. There are some beautiful flowers that do produce fruits, such as Passiflora Incarnata (passionflower vines;) these will absolutely need to be fermented, as the seeds are found within a fleshy, sweet fruit.
Poppies don't require fermentation; their seeds grow in a fibrous pod. You simply dry them!
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| Poppies don't require fermentation; their seeds grow in a fibrous pod. You simply dry them! |
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| Sunflowers don't require fermentation; their seeds grow in protective shells on the flowerhead. You simply dry them! |
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| Sunflowers don't require fermentation; their seeds grow in protective shells on the flowerhead. You simply dry them! |
Not all vegetables need to have their seeds fermented, either. I've yet to see pepper seeds mold from a lack of fermentation, even after growing and saving seed from well over 100 varieties. As sweet as some of the peppers can be, this surprised me. Okra is another one that doesn't need to be fermented, as it produces seed via a fibrous pod. Grains (corn, oats, wheat), legumes (peas, beans,) brassicas (collards, broccoli,) lettuces, and most root crop seed won't need to be fermented, either.
Pepper seeds don't typically need to be fermented, you can dry these.
It sounds like we knocked a lot of them off of the list, huh? Don't worry- we've got several to watch out for! The riskiest seeds are going to come from plants with the highest sugar or carbohydrate content. Number one on our list? Watermelon! This sweet treat will feed a colony of mold very well with the flesh and sugar that is left behind on unprocessed seed. Squash is pretty bad about it as well- squash seeds are what molded for me initially. Tomatoes are the type that I ferment the most of, as I grow so many of them. Passionflower fruits, honeydew melons, berries, cucumbers, and cantaloupes should be fermented, as well.
It's very important to ferment tomato seeds. It helps to prevent the spread of disease, and it makes the seeds easier to manage at planting time.
Fermentation: The Simple Solution to Cleaner, Healthier Seeds with Higher Viability
Now that we have briefly discussed why to ferment and which seeds to ferment, let's discuss the benefits of fermentation and how it works a little more in depth.
When you ferment seeds, you're simply allowing the seeds to sit in water so that yeast can actively break down fruit residues and seed coats after removing them from the fruits. Yeast will naturally colonize from spores in the air; all you do is place seeds in a cup of water at room temperature. As they say, nature finds a way!
These micro dwarf cherry tomato seeds are a little earlier in the fermentation process. Note the cloudy water as the microbial life establishes itself.
Once the fermentation is complete, you're left with clean seeds that you'll lay out to dry, as normal. Let's do some bullet points for the benefits of seed fermentation:
- This process leaves no residue for mold to feed upon.
- Seeds are made less appealing to some pests that could be drawn in by the scent of those residues.
- You'll notice that the seeds feel and look cleaner, resembling the seeds from store bought packets (those companies ferment, too.)
- For some seeds, like tomatoes and cucumbers, breaking down that seed coat will also help to improve germination for the following year.
- Seeds are less likely to clump together, making it much easier to sow individual seeds the following season.
- Sometimes, pathogens can hitch a ride on seeds; fermentation won't stop all disease, but it's surprisingly effective at reducing the risk of disease from pathogens that tend to be found in the flesh and seed coat; of course, anything within the seed won't be affected.
- Seeds look more appealing and professional, which is important should you decide to trade or sell them.
4. Step-by-Step Seed Fermentation Process (It's Easy, I Promise!)
Saving micro dwarf cherry tomato seeds for seed trading, I ferment the seeds before washing them, drying them, labeling them, and storing them. This gives me clean, debris-free seeds.
If you're new to fermenting seeds, please know that this is an incredibly easy process and there's no need to be intimidated! We'll keep it simple:
1. Gather your fruits and collect viable seed. Don't leave large chunks of fruit with the seeds (like entire tomato cores.)
2. Place your seeds in a cup or jar. Including a little of the juice (tomatoes, watermelon for example) is perfectly fine, as it'll give the yeast more to feed on.
3. Add water (NOT CHLORINATED), about twice as deep as the seeds. You don't want an entire 8 oz glass of water, but you want enough to account for evaporation and the growth of scum along the surface of the water. It's easier to skim the scum off at the end, than it is to pluck seeds out of the scum due to water levels that are at or lower than the seed level.
4. Leave your cup for 3-5 days at room temperature, or slightly warmer. You'll likely see bubbles by the second day. Note that seeds fermented in warmer locations (70F or higher) will be finished faster than seeds in cooler locations (65F or less.) You'll get the hang of this part- just pay attention to #5!
5. When your seeds are done, it's going to be clear that your seeds have been colonized by yeast. The cup will stink, the water will be cloudy, there may be white scum or some mold growing on the surface of the water as well (this is okay! Just skim it off!) A bad sign to watch for is germination among the seeds. If you see root tips, you fermented the seeds for too long & they're done for- unless you can grow them right away.
6. Grab a fine mesh strainer, skim any gunk off of the top of the water, and pour your seeds into the strainer. Agitate them with your fingers to loosen any stubborn flesh or seed coats and rinse them well.
7. Lay your seeds out to dry on coffee filters or paper plates, spreading them out. Drying time depends on the size of the seed and the humidity within your home. I would dry large seeds for 10-14 days (usually 14) and tomatoes for roughly 7 days. Don't rush the drying process: remember, if seeds are stored with too high of a moisture content, they could still mold.
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| Orange Hat tomato seeds after being fermented and rinsed. Look how clean they are! They just have to be dried, labeled, and packaged. |
The Final Product: What Should Seeds Look Like?
Once the process is complete, you should have clean seeds that resemble the ones you originally planted from a packet. They won't have pulp residues, they won't be sticky, and they shouldn't stick together. Sometimes, doing large batches of seeds (like tomatoes) will result in some clumping. These clumps tend to be easy to break apart than clumps that result from fruit residue, and the seeds will not clump back up after separating. You'll notice that the tomato seeds will appear fuzzy, as well.
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| Have you tried fermenting your own tomato seeds? It's a stinky process, but it's a great way to promote better germination while helping to prevent contamination from mold and disease. |
Closing Thoughts & Discussion Questions
Seed fermentation is an easy skill to master, so give it a go and check out the difference in the quality of your hand saved seeds! It will provide you with professional looking seeds that maintain high viability, resist molding, and are less likely to attract pests.
- Have you ever had some of your seeds mold during storage?
- Do you currently ferment your own saved seeds?
- What were the very first seeds you ever saved?
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