Growing Squash: Increasing Garden Yield and Pollinating to Save Your Own Seeds

"Growing Squash: How to Increase Your Squash Garden Yield" explains why you might need to hand pollinate your squash.

Steps for Hand-Pollinating Squash Blossoms
Hand-pollination of squash blossoms requires a little time. When blossoms have begun to develop on your squash plants, take time one evening to identify some blossoms for pollination the following morning. You will be looking for blossom BUDS, not open flowers.

The male flower buds appear as small buds set directly on short stems on the squash vines. Locate a few mature male buds. Mature buds are usually slightly yellow, while immature buds are small and green.

The female flower buds appear as larger buds set on an enlarged immature ovary that may look like a small squash. It has not been pollinated, so it will not develop into a squash. Locate mature female buds that are ready to open the next morning. They usually begin to "yellow" the evening before they open, so look for a hint of color on the buds. The petals will still be tightly wrapped, although some buds may also have petals that are beginning to loosen for opening the following morning.

Very early the next morning, locate a male flower. Carefully pinch it off the vine at the stem. Carefully peel back and remove the petals, revealing the stamen. It should be full of bright yellow pollen. If possible, leave the stem so you can use it as a handle to hold the flower.

Locate open female flowers, and use the male flower like a little paintbrush to dust some pollen into the female flower. You will be able to see the yellow pollen grains sticking to the stigma. That's all there is to it.

If your purpose is to improve the squash yield from your garden plants, use several male flowers and dust several female flowers. When the pollen from one is used up, just use another flower. The more pollen you can use, the better. I usually repeat with two or three male flowers over a few female blossoms, which mimics natural insect activity.

Use flowers from the same species of squash...acorn squash with acorn squash, zucchini with zucchini, etc. You can also experiment with crosses, for example cross pollinate different pumpkin varieties.

TIP:
Squash blossoms begin to "yellow" late in the evening the night before they open.
Squash blossoms open at first light. You should pollinate as early as possible, and no later than 10am.

SEED SAVING
If you want to pollinate for pure seeds to save for planting, you will need to ensure a level of genetic integrity, even if it is only at a home garden level. The evening before you pollinate, locate the mature female blossoms you will pollinate the next morning. Using a short strip of masking tape, gently encircle the tips of the female buds to keep the buds from opening. Don't pinch the tape tight onto the bud. The next morning, prepare a male flower as above; I place it on a leaf near a taped female flower so it's handy. Carefully remove the tape, open the petals, and dust the pollen into the female flower. Tape the female flower closed again as soon as you have pollinated it to prevent any other pollen from entering. Tape gently around the petals only, being careful not to knock the female blossom off the plant. As the squash develops, the taped blossom will drop from the end of the squash as it normally would. To ensure genetic diversity in the resulting seeds, use pollen from 2 or 3 male flowers of the same species blended in several female flowers.

See Lesson One for information about identifying male and female blossoms.

Source:
Personal experience