Famed for its prodigious output and occasional monster-size fruit, zucchini squash (Cucurbita pepo) is an annual garden staple. But those prolific zucchinis don't come without a helping hand. Zucchini flowers require pollinators -- insect or human -- to bear their delicious fruit. Hand-pollination is a fun, simple activity suited for family members from young to old.
Reasons and Benefits
Zucchini plants have separate male and female flowers. For squash to grow, pollen must be transferred from male blossoms to female blooms. Wind is no help -- zucchini pollen is heavy and sticky. Bees often carry out the task, but their numbers may be low in some areas, particularly urban zones. Weather also plays a role. Cool, rainy days and high heat slow down pollinator activity. When limited or incomplete pollination occurs, zucchini fruits suffer. Hand-pollination ensures complete, thorough pollination and improves zucchini quality and quantity.
Male vs. Female Flowers
Discerning between male and female blooms is the first step in hand-pollination. Look at the stem beneath the bloom, and the flower's sex is clear. Male blooms have long, thin stems that look the same from vine to blossom. Female flowers hold a tiny zucchini right below their bloom, ready and waiting to grow. The flower centers also hold answers. Male blossoms have a fuzzy center anther, similar to a pollen-covered cotton swab. The bumpy, golden-orange center of female flowers is their sticky, pollen-receiving pistil.
Planning and Timing
Most zucchini plants produce all male flowers at the beginning of each season. Female flowers appear later, once pollen is ready and waiting. When plants have both male and female blossoms, the time for hand-pollination has arrived. Squash flowers open in morning and close at evening. Blooms are only receptive for one day. Plan your work for early morning, right after squash flowers open. Morning humidity helps pollen stick to its target. Don't be alarmed if some pollinators join you in your work. They're focused on the blooms, not you.
Pollen can be transferred with a small artist's paintbrush, but male blooms form perfect botanical brushes. The male flower's stem is your handle; cut it carefully where it connects to the vine. Then remove the flower's petals, leaving its pollen-covered anther at the center. Remove the petals from female flowers or leave them intact, whichever you prefer. Take the male flower and firmly, thoroughly cover the female flower's center pistil in pollen. You've now hand-pollinated your first bloom. One male flower pollinates several females, but be generous with each one. You'll enjoy the rewards come harvest time.
- University of Florida IFAS Extension: Home Vegetable Garden Techniques: Hand Pollination of Squash and Corn in Small Gardens
- Aggie Horticulture: Hand Pollinating Squash
- University of California Vegetable Research and Information Center: Fruit Set Problems in Squash, Melons, and Cucumbers In Home Gardens
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