Thursday, September 10, 2015

How to Save Summer Squash Seeds

I love September.  The nights start cooling off, but the days are still hot enough that the garden is still in full blown production mode.  Before all of the warm weather crops start dying off, I wanted to share a tutorial on how to save seed from summer squash plants.

As opposed to, say, tomatoes, squash plants do not have perfect flowers; meaning they do not self pollinate on their own.  They require the help of bees, or in this case, you.  Because of this, they are not the easiest seed to save successfully.  However, they are far from the most difficult, and anybody with a little know how can do it.  Today I'll be walking you through step by step.

As with all seed saving, the most important thing to remember is to choose plants that were grown from open-pollinated seeds.  Open-pollinated means that the plant will produce seed true to the parent plant.  Hybrid seeds are just the opposite: the seeds will not produce "true seed".
Open-Pollinated = Good for seed saving
Hybrid = Bad for seed saving

For this tutorial, I will be saving seed from an open-pollinated Rampicante Italian Vining Zucchini:

Keep in mind that this same process will work for seed saving from any summer squash plant.

First, lets talk flowers.  Squash plants have two types of flowers; female and male.
Female flowers appear at the base end of the squash, as shown in the photo on the left.
Male flowers appear on a single stem coming from the plant, as shown in the photo on the right.

Squash plants successfully reproduce when pollen from a male flower comes in contact with that of the female flower.  Most often this is done by the bees.
However, it is important to note that squash plants can cross pollinate with other squash plants.
Meaning: if pollen from a certain male pumpkin flower comes into contact with a female zucchini flower, they will successfully create a zucchini squash.  That zucchini's seeds, however, will be a mix of zucchini and pumpkin.
Your job when saving seed is to make sure that no cross pollination occurs.  You need pollen from a male and female flower of the same variety to produce true seed.
Though bees are amazing at pollinating on their own, you want to bypass them altogether here, since they can easily cross pollinate and ruin your seed. 
Your objective is to keep all foreign pollen away from both male and female flowers, and then manually pollinate (lets call it polli-'mate').

Before you can do this, you must understand the life cycle of a squash flower:

Left Photo: 
closed flower

Middle Photo:
open flower

Right Photo:
wilted, dying flower

When choosing your male and female flowers for seed saving, be sure to select ones that have not yet opened, but are approaching sexual maturity.  Before they open, you will want to tape the flowers shut, to ensure that no bees can access the pollen before you can.  Squash flowers always bloom in the early morning, so you will want to tape them shut the night before.

Flowers that are approaching maturity will be distinguished by displaying a yellowish color at the seams, and should be more "full" looking, as seen in the photo to the right.

The night before the flower is about to open, take a piece of masking tape and tape the opening closed:

You will want to do this with both the male and female flowers, as seen above.
For best results, male flowers should be used from a different plant than the female flower.  All plants  need to be the same variety of squash.  You will also want to use more than 1 male flower, if available.
Remember to BE GENTLE.  This is especially true with the female flower.  I ended up pulling the flower off of the squash the first time I tried this.

The next morning, it should be obvious that the flowers were going to open, but couldn't because of your tape job, as seen below:

This is the point where you need to work quickly.  Remove the male flower from the plant by snipping the stem several inches away from the flower.
Carefully cut through the tape on the male flower.  Cut off the top portion of the female flower, including the tape, and allow to open naturally.  Be sure not to let any bees or anything else contact the pollen in either flower, or you will need to start again.

The stigma of the female flower (left), and the anther of the male flower (right).

Carefully remove all of the flower petals from the male flower to expose the anther.  You will notice it is naturally coated with yellow dust, or pollen.

Like a paintbrush, gently rub this pollen on all sides of the stigma of the female flower.
For best results, use two or three different male flowers to pollinate a single female flower.

Once finished, you will again tape the female flower closed.

This will ensure that no foreign pollen comes into contact and that the squash seed will stay pure.
Distinguish the pollinated squash by tying a string or ribbon around the stem.

Over time, keep an eye on the squash.  If pollination was successful, the squash will continue to grow and the female flower will die and eventually fall off (photo on the left).

If pollination was unsuccessful, the squash will stop growing, wither and die (photo on the right).

Here is a photo of my successfully pollinated squash plant:

Hand-pollinated summer squash plants must be left on the vine to grow until quite large.  You will know it is ready when the skin is tough enough that it will not be dented by a fingernail.

The number of viable seeds increases when the squash is left to sit after being cut from the plant for three weeks or longer, but I don't let mine go for longer than a month.  Store the squash in a cool, dark place while you wait.

When ready to collect seeds, cut the squash open and remove all of the seeds.  Rinse in a colander under running water to remove any flesh or debris.  You can rub the seeds against a mesh strainer to help loosen any bits that won't be removed by running water alone.

Dry seeds completely.
I usually do this on a wax lined paper plate.  Once dry, store seeds in a cool, dry, dark location.  Squash seeds retain viability for several years, so this process isn't necessary to do again for a while.

Unfortunately, there is no way of knowing if you were completely successful in producing pure seed until you plant the saved seed the following spring.  I currently have a very happy Rampicante in my garden as I type this, so I know that this particular seed saving experience was a success!

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