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The Plant Lady: Want your garden to produce? Here are tips to make summer fruitful

A farmer shows off some ripe strawberries at his field in Nipomo. Both of Nipomo’s weekly farmers markets will have closed by the end of 2018.
A farmer shows off some ripe strawberries at his field in Nipomo. Both of Nipomo’s weekly farmers markets will have closed by the end of 2018. jjohnston@thetribunenews.com

Having a lush, green vegetable garden is great – but only if the plants are supplying you with a crop. Low productivity is typically a case of simply waiting, as plants adjust to temperatures or grow large enough to support a crop. Ruling out other environmental/nutritional factors, pollination (or lack thereof, to be specific) may be the culprit.

Sometimes plants may need a helping hand. Various insects and birds are responsible for pollinating plants, but bees are the most abundant and important pollinator of the majority of vegetables. Bees are looking for pollen (protein) or nectar (carbohydrate). They often get confused while searching for pollen or nectar, manifesting in visiting a female flower thinking it has pollen or going to a flower assuming nectar will be present. In doing so, they are inadvertently moving pollen from anther to stigma. If your garden is not producing, here are a few simple rules and guidelines for vegetable pollination.

Cucurbits: Squash, cucumbers, melons, watermelons, zucchini, pumpkins

Plants in the Cucurbitaceae family are monecious, meaning they have both female and male flowers on a single plant. This means you only need one plant to produce fruits. If your plants are not producing (or not enough), then hand pollinating may be in order. This is a straightforward process, but you will need to be able to identify a female versus male flower. Females will have a swollen ovary at the base of the flower – this is the immature fruit. Males will lack this. A quick side view will easily help identify.

Often, I find plants have an abundant number of male flowers forming first, subsequently followed by female flowers. To hand pollinate, in the morning take a small paintbrush or Q-tip and swipe pollen from the center of the male flower (stamen). Find a female flower and swab the whole stigma (female part) with the pollen. In nature, it requires nine to 15 bees to pollinate one flower to ensure full-size fruit. Sometimes incomplete pollination will result in fruit starting to form but then rotting out. Female flowers only last one day, and once they close they are no longer receptive to pollen. Cucurbits are capable of cross-pollinating, meaning pollen from one plant can be moved to a female plant of the same species.

Tomatoes, Peppers, Eggplant

Members of this family (Solanaceae) are – for the most part – monecious. Their flowers however, are considered “perfect” – meaning they have both male and female parts. Once again, only one plant is required to set fruit. Tomatoes are pollinated by wind moving the pollen onto the stigma or by bees searching for pollen. Keep in mind these are not honey bees, but instead carpenter bees and others capable of buzzing. The bees need to be able to buzz (moving their muscles at a high frequency) to release pollen. If fruit is not forming on your plants, you can gently shake the plants to act as the wind. You can also move the pollen by hand with a brush after buzzing with a hand-held pollinator or even an electric toothbrush. Keep in mind that many heirloom varieties of tomatoes or other large fruiting types do not produce much fruit simply based on their genetics. Additionally, very hot varieties of peppers may take two years to really start producing.

Tomatillos

Tomatillos are an exception in the Solanaceae family – they have perfect flowers, but are incapable of self-pollination. Many people will plant a tomatillo but are later disappointed when fruit does not form. To ensure you have fruit, plant at least two of the same variety in close proximity so they can cross-pollinate.

Corn

Corn almost never needs help being pollinated, as the wind does the job. Here are a few important planting tips for other corn pollination considerations. Because wind is responsible for corn pollination, plants should be placed close together in blocks so wind moves pollen from all directions. Also, different varieties of corn should be planted at a minimum of 150 feet away from each other. Corn can easily cross pollinate, and if this occurs you will end up not with the corn you expect, but a hybrid variety instead.

Strawberries

Everyone loves a nice, big, juicy strawberry, so it can be disappointing when fruit fails to fully develop. Besides various environmental factors, poor pollination can cause malformed fruit. Unlike other vegetables, with strawberries the part that we eat is actually the receptacle. The swollen ovaries are what we think of as the “seeds” on the plant. To ensure plump, fully formed strawberries, each female stigma needs to be pollinated. It is estimated that 15 to 25 insects need to visit a strawberry flower to fully pollinate it. These pollinators can be various flying insects, with bees making up the majority. Wind can also pollinate, but efficacy is lower. If you notice poor pollination, grab a paint brush or Q-tip and move pollen around. While they are capable of self-pollinating, studies show that cross-pollinating strawberries will result in larger fruit.

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