'Why aren't my vine crops putting on fruit?' That's a popular question from gardeners trying to grow pumpkins, melons and cucumbers, especially early in the growing season.
Sometimes the problem is the gardener's fault, and other times Mother Nature is to blame.
Overfertilizing will cause a decrease in fruit production for all garden plants, not just vine crops. Excess fertilizer pushes the plant into grow mode, where the effort of the plant is directed to making foliage instead of setting fruit. Plants will eventually push out of this phase, but early fruit production has already been lost. Overfertilizing is the main gardener-caused reason for decreased fruit set.
When Mother Nature is to blame, there are numerous reasons for growing problems.
If you have flowers, but no fruit is setting on, there are a couple of things to look at.
Are these the first blossoms the plant is producing? If so, they may be all male flowers, since male flowers are always the first to appear. To find out, look behind the bloom. If there's nothing there, it's a male flower. If, however, there's a miniature fruit, it's a female flower. If there are no female flowers on the plant, all you can do is wait for them to appear.
If you have both male and female flowers on the plant, but still no fruit setting, it may have to do with the lack of bee activity. Vine crops are pollinated by bees, as opposed to tomatoes and peppers, which rely on the wind to carry the pollen. Unfortunately, bee numbers have been taking a big hit lately because of pests and other little-understood problems. However, there are still enough of these wild pollinators around to get the job done. What could be the source of little or no pollination could be that sometimes bees just don't work. For example, on rainy or cloudy days, honeybees don't leave their hive to work. So, if you've had a spell of rainy or cloudy days, the pollination simply isn't taking place because the bees are not working.
If you have both male and female flowers, but the bees aren't working, you can pollinate the plants yourself. Folks who participate in competitions for the largest pumpkins do this to make sure they get an early start on that prize pumpkin. It can actually be done on all vine crops - with ease.
Some gardeners will use a small paintbrush - like those found in children's watercolor paints - to transfer the pollen from the stamen - the center portion of the male flower - and lightly brush it onto the stigma - the center portion of the female flower. Another method is to pick the male flower and carefully tear the petals off, exposing the stamen, and then transfer the pollen directly to the stigma of the female bloom. Either of these methods will work for hand-pollinating plants.
If you can't wait on Mother Nature to kick your vine crops into gear setting fruit, try hand-pollinating a few of them yourself. It's a good way to get a jump on your neighbors for bragging rights to the first ripe cantaloupe or watermelon, or the biggest jack-o'-lantern on the block.