Pumpkin Sex… the other side of Curcubit Pollination

My Mother-in-Law would be horrified at the title of this post, she would rather it was termed Pumpkin Relations… however here goes.

Cucumbers, Pumpkins, Squashes and melons have been favourites amongst gardeners for generations. One is able to carry seed through generations from your initial purchase as long as you keep the seed pure. This is quite difficult as these plants are generally bee pollinated and bees can travel quite far in their search for nectar and pollen. So the chances of a natural crossing from a neighbours plants is very possible.

I’m going to base pollination article on pumpkins, however all of the information is easily carried across to cuc’s, melons and any “curcubit” type vegetable. Typically in the garden environment there are 4 species of Pumpkin that we make use of. Broadly speaking the different species of pumpkin will not cross pollinate. So using Pumpkins as an example, if you had Curcubita pepo, C moschata, C maxima and C mixta you could grow one of each of all four varieties in your garden without concern for cross pollination. However your neighbor a few or even up to 10 roads down who also has a veggie patch could most definitely contaminate(well the bee’s actually) your variety.

So, what is one to do? The best answer is to hand pollinate one or two flowers of each variety. Here is a step by step instruction of hand pollination for pumpkins, cuc’s and melons. The melons/cuc’s are a bit harder as the flowers are smaller and you may go through a few attempts before you are comfortable and get it right. Aren’t we lucky we work with forgiving plants. Just remember you only need to save one fruit to provide you with enough seed for a few years.

Step 1: The evening before you plan to hand pollinate select two flowers a male that is just about to open and a female that is also just about to open. You can normally see this by watching the flowers for a few days and you will very quickly be able to establish at what stage the flower is about to open. Make sure that the flower has NOT opened to allow a bee or insect in. Bee’s will typically push themselves into a flower even if it’s just slightly open. So timing is critical. Do not use a flower that you think has had a bee in it. Pick the male flowers that are about to open.

Male flower attached to female with a peg, the evening before pollination
Male flower attached to female with a peg, the evening before pollination

Step 2: Peg the two flowers together ensuring that the peg keeps the ‘opening end’ closed and wait about 12 hours. One of the problems with cucumbers is the fact that as the flowers are so small a peg will not hold them closed. One way to get around this is to have small gauze bags (for the guys…. A small bag made from your wife’s net curtains are good. I’ll just deny I mentioned it) or do what Bill a friend of mine dose and uses a folded page from the Farmers Weekly and a peg to enclose his flowers. Enclose the two flowers in the bag as for the peg method. You need to wait the 12 hours otherwise the “reproductive bits” will not be ready.

The male flower has been stripped of it's petals and is being used as a paint brush to transfer pollen.
The male flower has been stripped of it's petals and is being used as a paint brush to transfer pollen.

Step 3: Tear the petals all the way away from the male while trying to keep as much pollen on the anther as possible and VERY carefully open the female flower, insert the male flower and rub the male anthers onto the style of the female flower. Thereby transferring pollen between the chosen flowers. You should also mark the fruit so that you know which ones are hand pollinated and from where you need to save the seed. Just a light scratch will do, it will carry right through to maturity. We use cable ties once the fruit has clearly started to show growth.

Step 4: Very Important. Close the female flower with the peg again. And leave it on until there is definite growth on the fruit. For smaller flowers, keep the newly forming fruit in the bag for a few days and then it can safely be removed and used for the next vegetable.

Female flower is closed again after pollination. Spent male flowers are discarded behind. It's always good to use at least two male flowers per pollination.
Female flower is closed again after pollination. Spent male flowers are discarded behind. It's always good to use at least two male flowers per pollination.

Step 5: Harvest the fruit when fully ripe. For Pumpkins it’s when the stalk turns brown and for cucumbers it’s when the cuc turns yellow and/or the flesh is soft. Once cut, give the pumpkins three weeks so that the seed can fully mature. With cuc’s as soon as they are over-ripe they are ready to harvest seed from.

Step 6: Scoop the seed out, wash clean in a sieve and dry. Cucumbers will benefit from a few days of natural fermentation to allow the flesh to completely break down around the seed. The fermentation process also helps to protect the seed from diseases. Just scoop the flesh with seeds into a glass and leave in a warm place for 2-3 days, then wash the flesh off the seeds. Pumpkins don’t need to ferment. Drying is a simple process, just remember to stir the seeds everyday so that they don’t stick together. Once they are brittle and snap they are ready for storage.

Notes: If you do a search on the web you will be able to pick up a number of techniques. One that will also work quite nicely is the paintbrush method of transferring pollen.

This may seem like a process, but bear in mind that you only need to pollinate a single pumpkin or cucumber to give you enough seed to start a farmers market. So don’t forget to share some seed with family and friends.

5 thoughts on “Pumpkin Sex… the other side of Curcubit Pollination

  1. Johan says:

    1) How do you know the difference between a male and female flower on the pumpkins etc

    2) how do you harvest tomato seed when you put the seed on a news paper it stick to the paper is there a special way of cleaning the seed

  2. phillip says:

    i’ve planted butternut. problem that i have is that there are the most beautiful leaves and little or no fruit. please advise what the cause could be. i feel like pulling them all up. what should i do?
    regards
    Phillip

  3. Fascinating and I will want to try this. Please note that the links to your photographs are broken so they are not visible and I suspect they are rather useful for the sake of understanding this tender subject.

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