Not a year goes by when we don’t hear someone complain that their tomatoes, cucumbers, or squash didn’t set fruit. That there strawberries are misshapen or the ear of corn is not filled out. Or maybe it was their fruit trees dropped all their flowers and no fruit to show for it. Oh, the plants grew like crazy and blossomed to beat the band but when it came time to produce? Little or no fruiting occurred. That’s where hand pollination come’s in.
If you are an urban gardener it can really be a challenge, you have to end up doing the work of bees. Balcony gardens are particularly prone to pollination problems because they don’t get as much insect-traffic or crosswinds as ground gardens do. Sometimes hand-pollinating is necessary to get any yield at all.
Bees are the world’s best pollinators for many of our crops. They are fuzzy and electrostatically charged, which also helps to hold the sticky pollen grains. Pollination can be accomplished also by flies, beetles, birds, butterflies, bats, and many other creatures. But they are not always available in the numbers that we need. So, short of raising our own hive of bees, what’s a gardener to do?
Hand pollinating is not difficult. All you will need is A small paintbrush or other soft small brush. That is the best tool for the job. Q-tips or a feather also work well! Your brush or swabs need to be clean and dry. Pollinate early in the morning, but after the dew has dried and do it in dry conditions. The pollen sticks to the bristles on the paintbrush just as it would stick to the hairs on a bee’s body.
Hand pollination is a process where you are the bee, pollinating the female flower of a plant, with the male pollen. To perform hand pollination, all you need is an open female and male flower or one self-pollinating flower. The pollen can be from the same plant, or from another plant of the same species, depending upon the reason for hand pollinating.
Some plants such as date palms, kiwis and papaya have male and female plants. Hand pollination is important if not enough male plants are growing nearby.
1. To cross pollinate two species to create a new variety of a specific type of plant. This is done to produce varying colors, disease resistance, or other genetic traits to the new variety. When this occurs with different varieties of the same kind of fruit it is called Hybridization.
3. To increase the likelihood of successful pollination, especially in the absence of bees and other pollinators. For example, pumpkin growers almost exclusively hand pollinate their female flowers, to assure good fruit set. Home gardeners usually need to hand pollinate corn to ensure a full ear. In a greenhouse there are no pollinators so hand pollination is essential .
The third one is the one we are most concerned with as home gardeners.
Pollination is when pollen grains from an anther, the male portion of a flower, are transferred to a female part in the flower, known as the stigma. In order for pollination to be successful, the pollen grains transferred must be from a flower of the same species.
After the pollen grains land on the stigma, they create a pollen tube through the length of the style or stalk connecting the stigma and ovary. Once the pollen tube is complete, the pollen grain will send sperm cells from the grain of pollen down to the ovary. When the sperm cells reach the ovary and the egg cells, fertilization will occur, which will result in the formation of the seed. Without the seed, there will be no fruit.
First, determine if your plant is self-pollinating or if it cross-pollinates.
Although all flowering plants rely on pollination for reproduction, there is a variation in how plants are pollinated. There are two types of pollination, called self-pollination and cross-pollination.
Self-pollination is the more basic type of pollination because it only involves one flower. Each flower contains both the male and female parts, all the necessary plant parts to make a fruit. (an example is the strawberry flower above) This type of pollination occurs when pollen grains from the anther fall directly onto the stigma of the same flower, pollinating itself. That doesn’t mean insects and wind aren’t important, though. They can help pollinate self-pollinating plants; for example, when bees light on the flowers, the buzzing of their wings helps to shake the pollen off into the stigma. You can mimic this by placing an electric toothbrush against the stem of the plant and turning it on. The vibration is much like the vibration of a bees wings. This works very well with the tomato plant. You can also use the paintbrush to transfer the pollen.
If your plant is self-pollinating, all you need to do is brush inside each flower, making sure the pollen gets down into the stigma of the flower.
Cross-pollination is a more complex type of pollination that involves the transfer of pollen from the anther of one flower to the stigma of a different flower. Many vine crops like squash or cucumbers produce different male and female flowers. The male flower will have pollen-laden anthers, are typically shorter and don’t show immature fruit. The female flower will usually have what looks like the tiny vegetable at the base.
If your plant is a cross-pollinater, use your brush to transfer some of the pollen from the male flower to the stigma on a female flower. You can also pick the male flower and shake pollen right into the female. Vegetable plants will have more male flowers than female flowers. Use the brush or swab to gently swirl around the anther of the male flower. Carefully swirl the pollen collected on the brush onto the stigma of the female flower. Touch all surfaces around the middle of the female flower. Collect pollen from multiple male flowers for each female flower on the plant.
The first flowers on a cucurbit (squash family) are male, and these may remain on the plant for about a day before falling off. Sometimes, this falling scares gardeners, because it seems like blooms are dropping and all is lost. But don’t fear, the female flowers come along soon, and they’re the ones that produce fruit. Female flowers show up on the plant usually a week or two after the male flowers start showing. After that, there should be both male and female flowers on the plant at any given time while the plant is still blooming.
If your plant doesn’t start bearing fruit in a few days after pollination, then something else might be wrong. Inadequate water, lack of sunlight, and nutrient-deficient soil or temperature can also cause plants to conserve energy and not bear fruit.
Corn, while it doesn’t produce showy petals, it does have both male and female flowers on each plant. The male flowers are called the tassel. That’s the part that looks like grass gone to seed that blooms at the top of the stalk. As the tassel ripens, pollen is shed from the center spike downward to the lower fronds. The female parts of the stalk are the ears located at leaf junctions and the female flowers are the silks. Each strand of silk is connected to one kernel of corn. Pollination occurs when pollen touches the strand of silk. This seems like pollination should be easy. The pollen drifting down from the tassel should pollinate the ears below, right? Wrong! 97 percent of an ear’s pollination comes from another plant, which is why it is important to know when and how to pollinate corn.
To pollinate corn efficiently, wait until the tassels are fully open and beginning to shed the yellow pollen. This usually begins two to three days before silk emerges from the embryonic ears. As soon as the silk emerges, you’re ready to begin the manual pollination of corn. Pollination will continue for another week under ideal conditions. Most pollen shedding occurs between 9 am and 11 am, after the morning dew has dried. Cool, cloudy, or rainy weather can delay or inhibit pollination. Snap the tassels off a few stalks and use them like feather dusters. Dust over the emerging silks at each ear. You’ll be hand pollinating corn for about a week, so use your judgment as to how many tassels you snap per dusting. Start at the opposite ends of your rows each night to help equalize the distribution.