Cucumbers are favorite summer garden treats, and to enjoy a crop this year you may want to try saving seeds for next year. Unlike other vegetables, the seeds from a cucumber you are eating can't be saved. The seeds at the eating stage are not developed and will not produce a plant. You can, however, leave some cukes on the vine and harvest their seeds later.
Allow a few select cucumbers to remain on the plant for about five weeks after harvest.
Remove the now-yellow-turning cucumbers from the vine after the five weeks. Place them in a protected, cool and dry area for another three weeks.
Cut the cucumber in half lengthwise. Remove the seeds, which are surrounded by a gel-like pulp, with a spoon.
Place the seeds and the gel substance in a glass jar for four days. Swirl the jar to stir the seeds twice a day.
Scoop off the seeds and the gel that have floated to the top after four days. Floating seeds are not viable for propagation.
Rinse the remaining seeds with water and drain them in a sieve. Run them through your fingers and make sure any gel on the outside of the seed is removed.
Place the rinsed seeds on paper toweling and let them dry for up to three days.
Place the dried seeds in paper envelopes. Place the envelope in the freezer for 48 hours to kill off any pests that may be on the seed, according to The University of Illinois Extension.
Remove the seeds from the freezer and store them in a cool, dry area, such as the refrigerator.