Most of us know that bees visit flowers to gather pollen and nectar to feed themselves and their young. But in order to provide the best range of flowers for bees and other pollinators, it's a good idea to understand a bit more about the roles pollen and nectar play in bees' lifecycles, and how we gardeners can best cater for them.
More on gardening for pollinators:
What is pollen?
Pollen is the fine, sticky residue you find on male flower parts (stamens). Usually yellow, but often orange, purple and even black, its primary role is fertilising female parts of the flower (stigma) to produce seed or fruit. When bees visit flowers, they gather pollen, some of which then falls off onto other flowers as they continue their journey.
Some bees are better at pollination than others. Contrary to popular opinion, honeybees aren't that efficient at pollinating, as they have smooth bodies and collect pollen in tidy balls (known as pollen baskets) on their back legs. Bumblebees have furrier bodies and therefore can be completely covered in pollen, which easily falls from one flower to another. However, they still comb it off and store it in tidy mounds on their legs. Some species of solitary bee are the most efficient pollinators of all, because they collect pollen on the hairy underside of their bodies, known as a 'pollen brush' or 'scopa'. It's thought that one red mason bee can pollinate the same amount of apple blossom as 125 honeybees.
How do pollinators use pollen?
Pollen is mainly used by bees. Packed with protein, Queen bumblebees use pollen to engage their ovaries after hibernation, so they can start laying eggs. Bees also collect pollen and use it to feed their young, which makes them grow strong and healthy. Some pollinators eat pollen, such as some types of beetle and wasps.
Pollen varies in quality – certain flowers bear more protein-packed pollen than others, which can help inform our planting choices as gardeners. Studies of bumblebees have shown that the bee grubs fed the most, high-quality pollen turn into the healthiest, most robust bees.
The flowers that offer the best quality pollen are members of the legume family, Fabaceae. These include clovers, peas and beans, lupins and trefoils. Simply by mowing our lawns less often we can encourage clovers and trefoils to flower, providing a much-needed source of pollen for bees.
What is nectar?
Flowers use bees to ensure pollen is transferred from male to female flower parts. In return, they produce a sugary liquid called nectar. Nectar lures bees in and rewards them for their efforts in pollination. Nectar is essentially sugary water, and is largely the same in all flowers, although some flower 'nectaries' refill with nectar more often than others. For example, borage flowers refill with nectar every two minutes.
How do pollinators use nectar?
Being so sugary, nectar is packed with carbohydrates, which give bees the energy they need to fly. Indeed, it's thought bees can live for only 24 hours without nectar, unless they're hibernating.
Other pollinators use nectar, too, including butterflies, hoverflies and other flies, and some beetles. They all use the energy from the nectar to find mates and establish nests.