Squashes are notorious for being highly productive, but sometimes they need a bit of help to get started. If your plants are flowering like mad but not producing fruits, it’s time to start hand-pollinating them to speed things along.
Why Hand Pollinate?
Hand pollination is a useful technique when there aren’t many natural pollinators such as bees around, either because it’s cold or rainy, or because crops are growing under cover in a greenhouse or tunnel. Hand pollinating is also a simple and effective way to boost your yields, ensuring good fruit set for a reliable harvest.
All types of squashes can be hand pollinated including pumpkins, melons and zucchini.
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It's easy to tell male squash flowers (on the left) from female ones
Male vs Female Squash Flowers
Squashes have separate male and female flowers. Before we hand pollinate we need to know exactly which is which.
When you compare male and female flowers side by side it's easy to see the differences. Male squash flowers have a straight stem behind the bloom with no swelling. Peer inside the flower and you can see the stamens, which carry the pollen.
The female flowers have a very obvious swelling behind them. This is the immature fruit, which will begin growing once it has been pollinated. Peek inside a female flower. You can clearly make out the stigma, which is where the pollen needs to be in order to fertilise the bloom.
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Squash can be hand-pollinated using a paintbrush or by directly rubbing the stamen of a male flower against the stigma of a female flower
Hand-pollinating Squash
A soft-bristled artist’s paintbrush is ideal for pollinating squash blossoms. Use it to tickle pollen from the stamens of a male flower onto the brush. You should be able to see the yellow pollen on the brush end. Once you’ve done this, transfer it onto the stigma of a female flower by gently stroking the brush over it. And that’s it!
If you don’t have a paintbrush, you can simply detach the male flower from the plant then peel back the petals to expose the stamen and its pollen. Now – carefully – dab the pollen onto the stigma of an open female flower to pollinate it.
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When saving squash seed it's essential to isolate individual squash blossoms
Hand Pollinating to Save Squash Seed
Hand pollination is also useful when you want to save seeds of your favourite varieties. Squashes readily cross-pollinate with each other, so the only way to guarantee that seeds will produce plants that are the same variety as their parents is to prevent pollination by insects. You can then hand-pollinate to ensure that only pollen from plants of the same variety reaches the female flower.
You don’t need to isolate the whole plant, just one or two female blooms that will carry your seed. Cover the flower with a light, breathable fabric such as muslin. Tie the fabric around the stem at the back so the flower is completely enclosed. Then, when it opens, remove the fabric and hand pollinate. Return the cover once you’re done and keep it in place until the flower drops off and there’s no further risk of cross-pollination. Mark the stem of the developing fruit with a ribbon so you know from which fruits to collect your seeds.
