Garden Word of the Day
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Pollinators are animals that carry pollen from flower to flower. This pollen then fertilizes female flowers, allowing plants to produce fruit and seeds.
Without pollinators, we would be in a bad way. The U.S. Dept. of Agriculture tells us, “Of the 100 crop species which provide 90 percent of the world’s food, over 70 crops are pollinated by bees.”
Fruit set failure often means there are not enough pollinators. Insufficient pollination can also lead to blossom drop, crooking, and poor harvests. Today, we will find out who the pollinators are and how to attract more of them to the garden.
How does pollination occur?
Some plants have the ability to self-pollinate. If pollen grains can be moved from the male (anther) to the female (stigma) within the same flower, it is called autogamy. If pollen grains are carried from the anther of one flower to the stigma of another flower, while still on the same plant, it is called geitonogamy. When the pollen must be taken to the stigma of a different plant it is called cross-pollination, xenogamy, or allogamy. In some cases, self-pollination occurs before the flower even opens! This is called cleistogamy, but it has nothing to do with pollinators, so we will leave those flowers to themselves - which is what they seem to prefer anyway.
How do pollinators move pollen?
Even in the case of self-pollinating flowers, something is needed to break the pollen loose from the anther so that it can stick to the stigma. Note for those with allergies: pollen is very sticky. Rubbing or rinsing with water will not remove pollen. Soapy water is needed. So, as pollinators land on a flower, pollen sticks to them. Walking around on a flower knocks pollen loose to fall on the stigma and to stick to the body of the visitor. Next, that visitor flies, walks, or crawls away, carrying that pollen with them. When they visit the next flower, pollen is knocked loose from the anther and the pollinator’s body and the chance of fertilization starts going up. Some pollinators end up looking like Charles Schultz’ Pig-Pen, a walking cluster of pollen grains. Others have evolved with pockets on their legs! Honey bees and other apid bees have a pollen basket, or corbicula, on their legs that hold pollen wetted down with nectar. Other bees have a pollen basket called a scopa, on their abdomen. Whether they carry it on purpose or not, pollinators are drawn to flowers for several reasons.
How flowers attract pollinators
Plants have evolved with specific characteristics that attract the best pollinators for their needs. In some cases, the relationship is very specific. Figs are only pollinated by a fig wasp. No fig wasp - no figs. In most cases, plants go for the hard sell to attract as many pollinators as possible, using several different characteristics:
Installing a wide variety of plants is one of the best ways to attract pollinators.
Who are the pollinators?
There is far more to pollination than just the 1,000 different species of native, mostly non-stinging bees in California (4,000 nationwide; 20,000 worldwide). Bats, flies, moths and butterflies, beetles, birds, wasps, even lizards and monkeys can be pollinators. For that matter, so are we! As we walk through the garden, pollen attaches to our skin and clothing, to be deposited on the next plant we approach. We have also been known to hand-pollinate plants on purpose. More often, pollinators co-evolve in mutually beneficial relationships with their nectar and pollen food sources.
How to attract pollinators
First and foremost, get rid of the toxins that kill these beneficials. Broad spectrum insecticides, herbicides, and pesticides, even when they claim to be safe, should be avoided. They cause too much of an interruption in the normal, natural cycle of things. Yes, it means a few more pests in the garden, but it also means less toxins and more pollinators.
Second, pollinators need fresh water. While you do not want to create mosquito breeding grounds, bird baths, fountains, and other water features make lovely additions to the garden while providing water for pollinators.
Third, you need to provide adequate food and shelter for pollinators. Now, before you go out and buy one of those new fangled bug hotels, know that research does not show they are effective. In fact, these artificial clusters end up being breeding grounds for pests and diseases of pollinators! Most native bees are ground-dwelling, so they wouldn’t use them anyway.
You can certainly install a bat house, but most of the shelter you provide will be the same plants you install to provide pollinators with food. Use these strategies to provide shelter:
Plants that attract pollinators
Plants can be divided according to the pollinators they attract:
Butterflies also benefit from access to your compost pile and a patch of mud. They use the mud as a source of both water and minerals, and they enjoy eating rotten fruit.
Going native through the seasons
Since evolution is a really slow process, one of the best ways to attract a wide variety of pollinators to your garden is to install native plants. Native plants already provide for these beneficial insects and birds. You will also want to ensure that there are flowering plants available throughout the year. Not only will this help the pollinators, it will make your garden and landscape look better! Perennial natives, such as manzanita, make the job of attracting pollinators far easier. Here is a list of some California native plants that attract and provide for pollinators:
Video of male carpenter bee (Kate Russell)
Let it go to seed
All too often, we sabotage ourselves at the end of each growing season. Rather that pulling (never pull!) or cutting (better) spent plants, leave them in the ground (best) to go to seed. Not only will this provide for local pollinators, but it can also give you seeds for next year’s crops! I always let things go to seed. Now, as the seasons change, I find lettuce, escarole, cosmos, carrots, and more, growing where I never planted them, but where they can grow without any help from me.
Other causes of low pollination
Sometimes, pollinators are not the problem. Other causes of low pollination rates include:
For region specific planting advice, check out the Pollinator Partnership’s interactive tool. Simply type in your zip code and they provide valuable information about suitable plants that will attract pollinators.
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