Self-pollination occurs when the flower of one plant can pollinate a flower on the same plant.
Nearly every piece of fruit we eat (and many fruits that we call vegetables) would not exist without pollination. When creating a foodscape, space constraints can be a deciding factor in plant selection. While plants that cross-pollinate, those that use flowers from two different plants of the same species, often produce bigger and better yields, botanists have nurtured many self-pollinating varieties that can be used on balconies, windowsill gardens, and small yards.
How does pollination work?
Pollination refers to the transfer of pollen (sperm cells) from the anther to the stigma of a flower (angiosperm) or the ovule (gymnosperm), and the resulting fertilization of an embryo. Plants that use cross-pollination expend a lot of energy attracting pollinators. They use bright, colorful flowers, sugary nectar, and sweet aromas to attract the beneficial insects and bats that carry genetic information from plant to plant. Plants that rely on self-pollination tend to have smaller flowers because most of the pollen transfer occurs by falling onto the stigma as the flowers close. Wind, bees, moths and butterflies, birds, bats, and even rain may also play a part, but infrequently. If self-pollination occurs within the same flower, it is called autogamy. When it occurs between different flowers on the same plant it is called geitonogamy.
Pros and cons of self-pollination
The most obvious advantage of planting self-pollinating varieties is that you will only need one of them. It also means you can get a harvestable crop without the help of bees or other pollinators, which might be in short supply in your area. The disadvantage of self-pollination is that it limits genetic diversity and may reduce overall plant vigor. Just as inbreeding in mammals increases the chance for disease and deformity, plants can respond the same way.
Edibles that self-pollinate
Most sour cherry, peach, nectarine, citrus, and pear trees are self-pollinating. If you shop around, you can find self-pollinating plum, almond, and avocado trees, as well as some grape varieties. Many vegetables self-pollinate, including peppers, peas, beans. tomatoes, and eggplant. Fruit cocktail trees are one way to reduce space requirements while still taking advantage of self-pollination. These trees have several varieties grafted onto the same root stock, so they are technically self-pollinating.
Why is this important?
Understanding which plants self-pollinate can help you select the best plants for your garden. Fruit and nuts trees, in particular, are an investment of time and money. If you only have room for one, you have to make sure that it can self-pollinate if you are going to get a harvestable crop.
Be sure to read plant labels and get your plants from reputable suppliers. It can take a year or two to learn that a tree advertised as self-pollinating was a marketing scam and then it is pretty damn hard to dig it out and start over.
You can grow a surprising amount of food in your own yard. Ask me how!