How to master blueberry pollination – Part I

Blueberries need plenty of TLC to produce their much-loved fruit. To produce big, juicy fruit, they need good pollination. For each berry to develop, a blueberry flower requires at least 10 visits from a honeybee.

A honeybee visiting a blueberry flower
Blueberry flowers need 10-15 visits from a honeybee to produce the biggest, juiciest berries it can. 
(Photo credit: Adobe stock [272462591])
Why do plants produce fruit?

Plants have multiple strategies up their proverbial sleeves to ensure reproduction. Because they are literally stuck in the ground, they often enlist help from animals to get the job done.  Many plants produce vibrant flowers to lure bees to transfer their pollen between flowers. After pollination the job of spreading seeds that form still needs to be done.  Fruits are not nature’s gift to us. They are more like a Trojan horse, but instead of angry soldiers, the gift is filled with harmless seeds. Fruits are essentially a plant’s way of wrapping its seeds into delicious, colourful packaging for animals to consume. Animals eat the fruit, make the poop et voilà! the seeds are spread far and wide. 

Producing fruit is no mean feat, however. To generate a single sweet, juicy, and colourful fruit requires plenty of energy and nutrients. Plants therefore need to focus their energy when it comes to producing them, only investing their resources into fruits that contain plenty of seeds.

Blueberries require a lot of work to pollinate

Blueberries are quite tricky to pollinate. They require more pollen and a much higher frequency of visits from honeybees to produce fruit than most crops.

Illustration comparing a blueberry flower to an apple flower (not to scale).
A blueberry flower has 106 ovules on average, compared to an apple flower which has ten ovules.
(Illustration: Willem Augustyn-Goussard)

Every seed a plant produces comes from an ovule fertilised by a pollen grain. The number of ovules differs between plants. An apple flower, for example, has ten ovules. Therefore it requires at least 10 pollen grains for all the ovules to be fertilised. By contrast, blueberry flowers have up to 10 times as many ovules as apple flowers, with 106 ovules on average. This means that blueberries require many more pollen grains per flower to make large fruits. The more of the blueberry ovules are fertilised, the bigger the berries will be. This also helps the fruit develop faster. Bigger berries, that reach the market faster, means better return on investment for farmers. 

While a single visit by a honeybee to an apple flower can transfer enough pollen to fertilise every ovule, a blueberry flower needs 10-15 visits from a honeybee to produce the biggest, juiciest berry it can. If that’s not a tough ask already, blueberries also carry more flowers per hectare and per week than many other crops. Typically, there are roughly 10 000 000 blueberry flowers per hectare as opposed to 650 000 apple flowers per hectare. To be fair, apple trees only flower for two weeks, while blueberry bushes can flower for 10 weeks. That still leaves 325,000 flowers per hectare to pollinate per week for apples, compared to one million blueberry flowers per week, per hectare.

More happy honeybees lead to better blueberry yields

In order to produce bigger, juicier fruit, you need good pollination. The more happy honeybees are actively foraging and transferring pollen between blueberry flowers, the more seeds will be fertilised and the better your blueberry yield will be. One hectare of mature blueberry plants requires at least 10 beehives for effective pollination.

In South Africa, blueberries also flower during winter. Colonies have to work harder to maintain their brood at an ideal temperature in cool weather. When it’s very cold, cloudy or raining, an insulated hive helps bees stay warm so that they can focus on foraging.
By ensuring you stock enough well-insulated hives, you are planning for success with blueberries by maximising pollination, no matter the weather.

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