Seed Saving from Cucumber

Cucumbers are insect pollinated and will cross with any other cucumbers or gherkins nearby.  You need around a quarter mile isolation to make sure that your plants won’t cross. 

It is possible, although fiddly, to hand pollinate cucumbers.  Grow plants under a fleece tunnel to exclude insects.  Make sure that you exchange pollen between different plants to keep the diversity of your variety. 

  • Hand pollination: Method 1
  • Examine the flowers on the cucumber plants in the early morning. Determine which are the male and which are the female blossoms. The female flowers have a miniature cucumber at the base of the petals. This is actually the ovary on the plant where the fruit forms. You must have at least one male blossom, which contains the pollen on the stamens inside the petals.
  • Pinch one of the male flowers off the vine and remove all the petals to expose the stamens. Do not shake the blossom vigorously since this knocks off the pollen grains.
  • Touch the stamens to the stigma inside the female flowers. This leaves pollen stuck to the stamens and the cucumber blossom is fertilized. When the female flower dries up, the fruit grows and develops.
  • Hand Pollination: Method 2
  • Locate the male flowers on the cucumber vines. Take a small, clean paintbrush and drag it across the stamens to gather the pollen grains.
  • Brush the collected pollen onto the center portion of the female blossom. Leave the female flower alone after pollinating the bloom.
  • Dip the paintbrush into another male flower and keep pollinating the cucumber flowers. Ideally there will be a male flower for each female flower, but using the same male blossom is fine as well.

Cucumbers need to be ripened well beyond the edible stage.  They will become much fatter, and green varieties will turn a dark yellow brownish colour, white varieties a paler yellow. Keep for a week or so after picking to let the seeds mature fully. 

Scoop out the seeds and surrounding pulp into a jam jar, add a little water and stir well.  Leave the jar on a sunny windowsill for 2-3 days for the seeds to ferment.   On the third day, fill the jar fully with water, and stir well again.  The good seeds should sink to the bottom of the jar, leaving pulp, debris and empty seeds floating on top.  Gently pour off the water and debris, refill the jar, and repeat.   After a couple of rinses, you should be left with good seeds at the bottom of a jar in clean water.  Drain off the water, and spread out on a plate to dry well.

Cucumber seeds will last for several years if dried well and stored somewhere cool. 

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