Pollen production can be a real pain, but for gardeners, an abundance of healthy, ripe pollen is the rich vein of gold that produces our most popular food crops, from apples and cucumbers to tomatoes and corn. Without pollination, most plant and animal life in our gardens—and on our planet—would cease to exist.
Pollens are as distinct as the plants on which they’re found. Tiny, dry, wind-transferred pollen types (such as corn and ragweed) are the bane of hayfever sufferers. Larger, sticky, insect-transferred varieties (such as fruit and squash) come on showy, scented flowers designed to attract pollinators.
Pollen grains develop at the heart of blossoms in structures called anthers, atop stalklike stamens. As pollen ripens, the anthers open. Wind or insects transfer the pollen grains, which contain male reproductive cells, to the tips of pistils, the female parts of blossoms. There the pollen germinates (much like a seed does), each grain sending a tube down into a pistil to the flower’s ovary, where it fertilizes a seed-producing ovule.
To generate a bumper crop of almost anything in a growing season, this chancy process must take place hundreds, thousands, even millions of times.
The life span of a pollen grain is fairly short, ranging from a few hours to a few days. To improve the odds that at least some ripe pollen will land on desirable pistils, plants produce vast volumes of the stuff—at least, that’s the game plan. But a lot can go wrong along the way.
Soil nutrients, moisture levels, weather, and sunlight all influence pollen production. Temperature is crucial—the ideal pollen-germinating temperature for most plants is 65ºF to 75ºF. Germination generally slows or grinds to a halt when nights drop below 60ºF, days are above 85ºF, or humidity tops 70 percent. Though airborne pollen usually peaks between 5:00 a.m. and 10:00 a.m., pollen production can be eccentric. For instance, some varieties of avocado shed pollen in the morning and receive it in the afternoon, while others do the opposite.
You can help maximize pollen production and germination in your garden by taking a few simple measures:
Test your garden soil regularly. Plants need balanced nitrogen, phosphorous, and potassium levels for blossom production, and they require adequate levels of calcium and boron for healthy pollen development. Uptake of these vital nutrients suffers if soil pH is lower than 5.5 or higher than 7.5. (Most garden plants grow best when the soil PH is between 6.0 and 7.0.)
Select plants suited to your climate. In hot-summer regions, plants such as muskmelons and tomatoes stop ripening pollen in July and August. Early-blooming varieties, such as Early Goliath tomatoes, are a good bet in these regions—they ripen enough pollen to produce good crops before temperatures become too hot.
In short-summer regions, cool spring temperatures delay pollen development until it’s too late for long-season crops to mature. Try early-maturing varieties, such as Park’s Whopper Hybrid cantaloupe, in these regions—they ripen within a relatively narrow window of opportunity.
Maintain even soil moisture. Water helps plants take in the nutrients that encourage blossom development, so drought conditions can dramatically reduce pollen production. Make sure pollen-producing plants have a consistent amount of water, but avoid top-watering, which washes delicate pollen off flowers and out of the air.
Sandra Dark is a garden and science writer based in Norman, Oklahoma.