Unless your garden is a large multi-acre field or you only grow a few types of cucurbits (squash, zucchini, cucumbers, melons, etc.) saving seed requires a few simple steps. Isolation of these crops that easily cross-pollinate is difficult at best in a small home garden. Growing only one type of each species is the easiest way to save seed from various cucurbits. As long as your close neighbor is not growing different crops of the same species your seeds will pollinate each other true to form and all the seeds you save can be expected to produce pretty much identical crops the following season.
I don't know about you but I would have a hard time growing only zucchini, but not spaghetti, acorn, or my favorite and always abundant papaya pear squash. All four will cross with each other and create interesting, sometimes great, more often not so great vegetables if the seed is saved. You will be hard put to get a close replica of the original plant unless your bug population is very low, and that is usually not the case in an organic garden setting. Cucurbits are pollinated by a wide variety of insects, honey bees and other small bees being the main pollinators.
We love variety, so I grow a nice selection of different squash, many of which are of the same species. In order to save my own seed I must hand pollinate individual non-hybrid cucurbits to assure a pure seed. Keeping in mind that I am at best an amateur when it comes to saving seeds, especially ones that may cross with each other, here is how I hand pollinate a simple zucchini for hopefully pure seed. Most cucurbits can be pollinated in the manner I will show, but certain smaller melons, cucumbers, and gherkins, due to flower size can be a little harder to pollinate this way. So without going into too much mind numbingly boring detail prepare to be, well...mind numbingly bored.
Each zucchini has male and female flowers. The male flower contains the anther which produces pollen. The male structure is usually easily identifiable as the flower sits atop a thin straight stem.
Male flower one day away from opening
Note the male flowers anther situated in the middle of the bloom.
The female flower contains the stigma. It can be identified by its ovary or immature fruit.
The thicker stem (ovary/fruit) of the zucchini is fairly obvious in this specimen that is also approximately a day away from blooming.
The stigma can be seen in the center of this female flower.
When a male and female zucchini bloom appear to be close to opening I hold the flowers shut with masking tape gently attached to the ends of the soon to be opened blooms of both sexes. The male and female flowers do not have to be from the same zucchini plant. Early the next morning, before the insects are active, the male flower is untaped and cut from the plant, then the flower is carefully removed exposing the anther.
This picture shows my lazy assistant and I removing the male flower to expose the anther.
Note the anther is full of pollen
The remaining male anther is then used to brush pollen onto the untaped female flowers stigma, thus pollinating the plant. This should be done as quickly as possible in order to prevent insect contamination. Using more than one anther to pollinate each stigma will further increase the odds of successful fertilization.
Preparing to transfer pollen from the anther to the stigma. In order to take this picture the flower was slit down one side. This eliminates it as a good candidate for pure pollination due to my inability to securely tape the flower afterwords.
Gently brushing pollen onto the stigma
That's it! The female flower is then securely taped shut and marked with a ribbon for later identification. The one drawback to this procedure is that a zucchini must be allowed to fully develop, meaning get really big, for the seeds to be fully mature. This will slow down the production of other fruits on the plant due to the energy needed to support the large seed vegetable. If growing only a couple zucchini plants it may be wise to wait until the end of the season to perform these acts. With a regular squash, like an acorn, this will make no difference since the gourds will not be consumed until they are mature anyways.
Securely taped and pollinated female flower that will dry up and fall off as soon as the fruit begins to mature.
A fruit marked with red ribbon for easy identification at a later date. Loosely marked so as not to inhibit the cucurbits growth.
Even if you are not interested in saving the seeds off various cucurbits it is still good to know how to pollinate them. With the bee population possibly declining, plants that rely on them for fertilization could be faced with greatly diminished yields. Small scale hand pollination is an effective way of guaranteeing a good return on one's crop, especially in the smaller home garden.
There seem to be a limited number of reference books regarding the subject of seed saving. I currently have only three along with the treasure trove of information that can be found online. The first book I would recommend for any one just beginning to undertake this endeavour is "Seed Sowing and Saving" by Carole B. Turner. This book is not only fairly easy to understand but briefly covers a wide array of flowers as well as vegetable seed saving techniques.
"Seed To Seed" by Suzanne Ashworth takes a much more in depth look at seed saving. It is another excellent choice, but in my opinion seems to make seed saving in the home garden appear a bit complicated...it doesn't have to be. Read my first recommendation before tackling this wonderful manual.
I am currently enjoying "Breed Your Own Vegetable Varieties" by Carol Deppe. So far it is a real eye opener on how seeds selection and plant breeding is performed on a more intricate scale.
One other book I really like, and often turn to for guidance is "The New Seed Starters Handbook" by Nancy Bubel. A great reference tool for starting seeds that also briefly deals with seed collection. I'm always looking for more interesting books on seeds saving, what is everyone else reading?
While in no way an expert, I am committed to eventually becoming mostly seed self-sufficient not only for monetary purposes but for the knowledge and immense satisfaction that always seems to follow a subsistence pattern lifestyle.
I have started using plastic clothes pins instead of tape to hold the squash flowers closed. It seems to be much easier and just as effective. These clips are about worthless for hanging clothes anyway.