How to help out the bees when they’re busy
If pollination is hit and miss, follow these tips to help crops and insects, says Joyce Russell
Attracting pollinating insects is a key factor in producing bumper crops of fruit and flowering vegetables. But many factors combine to help or hinder the effectiveness of pollinators. Try these techniques to improve pollination rates in your garden.
WHAT IS POLLINATION?
Fruit trees in blossom and rows of beans dotted with scarlet flowers are a beautiful sight. You may be lucky and all of those flowers will set fruit or pods without your help, but this is not guaranteed, and poor pollination rates can lead to poor harvests. In a hot summer, for example, pollen is sometimes too dry to set; bees may also be scarce, and there may be no wind to scatter pollen where it is needed.
There are simple solutions to some problems and easy ways to optimise the chances that fruit will form. All that’s needed is an understanding of pollination and a few ways of overcoming any problems.
HOW IT WORKS
Pollination means moving pollen from one flower (or part of a flower) to the female pollen receptor in another flower (or part of the same flower). Fertilisation occurs when the two meet and a small fruit, pod or seed begins to grow. Pollination isn’t always an all-or-nothing thing either. Partial or incomplete pollination can lead to misshapen fruits, or small fruitlets that start to grow, but soon fall off, while failed pollination often results in flowers falling off the plant without setting properly.
Some plants have both male and female flowers (or other pollen-bearing parts, such as the tassels on sweetcorn plants); others have male and female parts within the same open flower; and some flowers, such as those of peppers, peas and some tomatoes, are closed, with male and female parts in proximity inside them.
Large flowers have evolved to attract insects to feed on their nectar. Pollen attaches to them and they then carry it from flower to flower. Some blooms are strongly scented, in pleasant or unpleasant ways, and these attract the insects they need. Closed flowers tend to be smaller and require a shake from the wind to allow pollen to drop to where it is needed within the flower. Wind helps pollen from open flowers to blow over a larger area, but animals, birds, or people brushing against plants can have the same effect. Some plants also use more than one method for transferring pollen, such as wind and bees.
FACTORS THAT AFFECT POLLINATION POLLEN TOO DRY OR TOO WET
Ideally, pollen should be slightly damp but not wet. The first tomato flowers will set fruit best if lightly misted with water (later trusses don’t need this). In dry weather runner bean flowers also benefit from misting. Use the finest spray possible to mist plants, to damp the pollen without washing it away.
To prevent rain filling large flowers, such as those of squash, and making the pollen too wet, partly cover them, leaving access for pollinating insects.
TOO EARLY, TOO COLD
Early broad beans sometimes flower long before bees are buzzing around the garden. Beans are self-fertile to an extent, but they set the most pods when insects lend a hand.
Give your plants a light shake to help the self-fertilisation process or sow slightly later in the year so plants are in flower when pollinators are active. Or continue to plant earlier and just hope that the spring is mild and your pollination rates will be satisfactory.
FEW INSECTS VISITING
Pollination is usually best in summer when plenty of insects are out in the garden. Encourage them by growing a range of flowers and herbs: borage, lavender, mint, comfrey and flowering brassicas are good choices.
Grow the flowers in pots and move them close to plants that need pollinators. If insects don’t do the job on larger blooms, such as aubergines, use a soft artist’s paintbrush, dampened between your lips, to transfer pollen.
NO WIND AND NO MOVEMENT
Many plants require some movement to allow pollen to drop to the right place within a closed flower. Pepper and bean flowers benefit from a tap or a shake to make this happen, particularly if grown under cover.
Sweetcorn produces pollen on the tassels at the top of the plant and this has to fall on to the silks at the end of the cobs lower down. Give stems a shake so pollen falls in a cloud to cover all the silks; poor pollination results in cobs with scattered kernels.
DAMAGE TO REPRODUCTIVE PLANT PARTS
If a male flower is damaged, the rates of pollination will not be adversely affected if you simply move the pollen from a different male bloom to the female for fertilisation. If a female flower is damaged, however, it won’t be able to grow a fruit.
You can identify female flowers on pumpkins, melons, cucumbers, and other squash, because they have a small swelling behind them that looks like a tiny fruit. Male flowers have no swelling behind them.
NOT ENOUGH VARIETIES
Apple trees need pollen from different varieties to allow cross-pollination to take place, as do many pears, sweet cherries and plums.
As well as growing a few varieties in relative proximity, check that those you have selected flower at the same time so that pollination occurs. If you do not have the space for a few trees, look for self-pollinating varieties. These produce fruits from the flowers of just one tree.