Saving Cucumber Seeds

We’ve survived the dog days of summer, and as autumn creeps in our plants start to look exhausted. Growth slows, the leaves may take on a yellow tinge or start to curl under, and productivity drops; the season’s end is approaching. Now is a good time to start weighing your options for seed saving. Do you have any heirloom or open-pollinated varieties growing in your garden? If so, you can save their seeds for future seasons. My Marketmore cucumbers are an heirloom variety cultivated in 1968 by Dr. Henry Munger, at Cornell University. This slicer was carefully bred over multiple generations to exhibit qualities like high productivity, uniform fruit and exceptional disease resistance. I was gifted some seeds early this spring and have been so thrilled with their performance that I made it a point to save seeds for my future gardens. I’m going to go through a brief step-by-step guide to saving cucumber seeds so you can successfully save your favorites too.

Step 1: Let it go

Yes, you read that right, neglect a cuke or two. The cucumber shown on the right in the photo above is the appropriate level of ripeness for eating. The cucumber on the left has remained on the vine well past it’s delicious eating period and been allowed to reach maturity, producing fully developed seeds. You can see that the cucumber has achieved 2-3 times its typical picking size and turned yellow in color. This chromogenic transformation indicates that the cuke is ready for seed saving.

Step 2: Fermentation

The best method for recovering viable cucumber seeds is to replicate the fermentation process that would take place naturally if you were to leave the fruiting body outside indefinitely and the seeds were to grow without intervention. Fermentation helps to minimize any harmful viral or bacterial growth on the surface of the seeds and it allows you to separate out undeveloped seeds. No need to be intimidated, this is not a complicated process. Cut your cucumber open lengthwise and scoop your seeds into a clear cup. You’ll want to get rid of any big clumps of flesh that come along with your seeds. Add water to achieve equal parts pulp and water. Swirl, then dump off the water and any seeds that are floating. The floaters are the underdeveloped seeds that will not germinate. Add water again and cover with a paper towel or coffee filter. Set your cup in a cool dark location for 2-3 days to ferment.

Step 3: Rinse & Dry

After your seeds have fermented for a few days carefully retrieve your cup. The clear cup should allow you to see a side profile of your seeds. Most should have sunk to the bottom, these are the viable seeds. You may also have more floating seeds now, they should be discarded. Gently pour off the water, any bacterial growth (this is normal, don’t be alarmed) and the floating duds. You’ll also want to pick out any big pieces of flesh that you may have missed in the previous step. Next, rinse your seeds to eliminate any residual debris or film. I use a small metal mesh strainer for this, but a colander with small holes or some cheese cloth could also work. After the seeds are well rinsed, you can spread them out in a single layer to dry. I use a plate, but a coffee filter, paper towel or parchment paper will do the trick. Let them dry for 5-7 days and VOILA you have cucumber seeds ready for planting! If you’re planning to save these seeds, I recommend storing them in a paper envelope (as opposed to a plastic bag) so that you don’t trap in any remaining moisture that may cause them to rot.

Step 4: Quality Control

I go one step further and test the viability of my seeds if I intend to share them with my fellow gardeners. I want to set them up for success, so quality is a must! This can easily be done by placing a few seeds on a damp paper towel in a plastic baggie. I put the bag in a warm, sunny location and check it again 3-5 days later. At this point, if your seeds are viable they should have started to germinate like the ones in the photo above. I have achieved 100% germination (4/4) with this simple seed saving process and you can too. Cheers, friends!

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