How to Hand-Pollinate Cucumbers in 5 Easy Steps
Cucumbers, with their bright, tubular blooms, rely on bees and other insects for pollination. Without a strong show of visits, fruiting lessens in number and quality. Garden expert Katherine Rowe explores when and how to hand-pollinate cucumbers for the greatest number of crisp, cool rewards this summer.
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Cucumbers are usually prolific producers given the right growing conditions, but even the best siting and care won’t have an impact without strong pollination. Cucurbits like melons, squash, and cucumbers have a tendency toward tenuous pollination due to their reliance on repeat visits from bees and other insects to produce fruit.
If you have healthy vines but a lack of fruits, dropped or underdeveloped ones, or curved, misshapen cucumbers, you may be looking at poor pollination. Hand-pollination is a simple way to boost yields and quality. It delivers pollen to all the right parts of the flowers in areas where bees are quiet, and even if they’re present, can increase production. The pollinated flowers develop into seeds and fruits for the summer harvest.
If you have more than one plant, experiment with hand-pollinating vs. not to see which yields the most. Or, give them all a sweep with the easy process to guarantee pollination and increase the harvest.
Hand-Pollinating Cucumbers
Why hand-pollinate cucumbers? Insufficient bee activity is a common reason for low yields. Cucumbers (Cucumis sativus) and other cucurbits rely primarily on honeybees and stingless bees like bumblebees for pollination. They visit cucumber blossoms mostly for their nectar, transferring pollen in the process.
Other crops may broaden their chances with self-pollination, wind, and insect pollination, but cucumbers need insect visits solely, and plenty of them. Bees shimmy into the tubular blooms to collect nectar and pollen, capturing it on their fuzzy bodies. They distribute the granules as they travel from flower to flower. Insects are necessary for pollination due to the large, sticky grains.
Cucumber flowers need at least nine visits a day from insects to ensure adequate pollination. Good pollination results in straight, well-formed, weighty fruits. To increase yields and ensure fruits in the absence of active bees, hand-pollinating the flowers does the trick. Hand-pollination involves a small implement (like a Q-tip or paintbrush) to collect the granules from a male blossom and brush them on the stigma of a female. Getting good pollen coverage and moving between flower parts is the key to the simple process.
Recognize the Flowers
Cucumis produces yellow, tubular flowers throughout the growing season. Depending on the variety, the vines produce one of three types. With traditional and heirloom cucumber varieties, they produce male flowers first, followed by female flowers days later. In the timeframe when the blooms overlap, insects must visit the different flowers to disperse the pollen from male blooms to female blooms.
Newer seedless or nearly seedless varieties produce only female flowers (gynoecious types) and are self-fruitful. And the last type has perfect flowers with both male and female parts, making pollination likely with a visiting bee.
To note is that different cucumbers can cross-pollinate with compatible species. While they won’t pollinate other cucurbits (a melon and a cucumber, for example), they will pollinate each other, crossing traits between varieties. If you don’t want to mix characteristics, hand-pollinate each variety independently. If you’re growing a few varieties and plan to save seeds, they likely won’t come true to type unless you have a vast space between them (a half mile or more, or physical impediments like buildings and trees).
What To Look For
Look for freshly opened flowers to hand-pollinate cucumbers, as they only open for a day. Male flowers are smaller than female ones, and they appear in clusters of three to five on short stems. The females appear singly on the longer stems of runner vines where they’ll produce. Look for a more prominent base or immature fruit on the females. Remember that the male flowers appear first, and the females follow in a week or more.
To manually deliver pollen, pollen collected from the anthers in the central pollen structure of the male flower will go to the stigmas in the female’s central column. Stigmas are sticky to hold the granules. The reproductive process begins with the deposit of a grain on the stigma’s crown.
Pick Your Tool
To get to the pollen and production centers, a gentle, grabby tool moves the particles. A small, soft paintbrush is a great option, or a cotton swab. These can reach the tubular floral centers.
You can also pick male flowers to pollinate female ones on the stem without a little tool.
How to Collect and Transfer
An easy way to hand-pollinate cucumbers is to pick a male flower and remove the petals so only the central pollen structure remains. Brush the column across the stigma in a female blossom to spread the grains.
To use a soft paintbrush or cotton swab, swirl the Q-tip or brush to reach the anther in the center of the male bloom. The more pollen captured, the better. Then, “paint” the stigma or lightly brush the female flower center for exposure. It’s okay if you can’t identify the specific flower parts – give everything a good brush in their central columns as you move between flowers for the best coverage.
The pollen from one male bloom should transfer to a few female flowers. Take care when hand-pollinating the female cucumber flowers, as they can fall off the stem easily.
Frequency and Monitoring
As female flowers form across the growing season, aim to hand-pollinate weekly if you have the time. If not, do it when you can to promote fruiting. The flowers open in the morning and close by evening, so capture them early in the day or mid-afternoon.
It takes patience both to hand-pollinate cucumbers and to see the rewards. There’s no obvious way to initially tell if our efforts paid off. The blossoms naturally wilt and droop at day’s end, and as the reproduction process is underway. Watch the base of the female flower for the small fruit to begin. A swelling immature fruit is a good sign that hand-pollination was a success.
Frequently Asked Questions
Why hand-pollinate cucumbers growing outside?
The cucurbits and their tubular blooms rely solely on insects, and primarily bees, for pollination. They need multiple visits to a single flower for stable pollination and fruit set. If bees aren’t active in your growing area, you may see underdeveloped, shrivled fruits, curved or deformed cucumbers, or none at all. If you have otherwise healthy-looking, flowering vines, experiment with hand pollination to boost yields.
Which cucumbers don’t need hand pollinating?
Parthenocarpic varieties are self-fruitful, meaning they don’t need insect or hand pollination to produce viable fruits. Newer cucumber hybrids may produce only or mostly female flowers and include seedless or “burpless” varieties. A pollinated seedless variety will show more seeds than an unpollinated one. ‘Muncher,’ ‘Diva,’ and ‘Quick Snack’ are a few that fruit without pollination.
Also, if you have plenty of active bees and other insects in your garden, your cucurbits will likely have enough visitation for hearty production without the need for hand pollination.
How can I boost natural pollination from bees?
Growing a diversity of plants is the best attractor for bees and other beneficial insects. Concentrate on nectar and pollen-rich additions to complement the edible landscape. Blend blooming perennials and herbs with the vegetable garden for a well-rounded system. Companion plants for cucumbers make good pairings that support overall growth.
It’s also important to consider pesticide usage and active pollination. As cucurbits, cucumbers are susceptible to a number of pests, including their own specialized cucumber beetle. If and when treating for other insects, follow application guidelines to minimize impact on beneficials.
