How Pumpkin Pollination Works

They call it “The Birds and the Bees” for a reason! Pollination is a core part of many plant species’ reproductive success. Pumpkins are no different! Pollination is the transfer of pollen to the reproductive parts of a female flower. This allows for fertilization and the development of fruit or seeds. 

Understanding Pumpkin Pollination: Key Factors and Techniques

Understanding pumpkin pollination is a major part (arguably THE major part) of growing huge gorgeous pumpkins in your garden. Pumpkins, like other squash, produce male and female flowers. The pollen from the male flower must make its way to the female flower in order to produce fruit. Some crops self pollinate - they do not need pollinators in order to fertilize their flowers and produce fruit. Corn is a great example of this as the plant produces pollen at the tassels on top of the plant which falls onto the silks of the ears of corn, fertilizing each silk and producing a kernel. Of course, many gardeners choose to hand pollinate their corn to ensure that every kernel is produced. Pumpkins on the other hand do not self pollinate. Their flowers must be visited by bees or the guiding hand of their gardener in order to produce fruit. Sometimes you can end up with small or misshapen fruit as a result of incomplete pollination. Perhaps the bees only dropped a little pollen on the stigma of the female flower - enough to fertilize, but not fully or healthily. 

The Biology of Pumpkin Flowers and Their Pollination Process

Pumpkin flowers are monoecious. This means that they have both female and male flowers on the same plant. This differs from dioecious species that have separate male and female plants such as spinach and asparagus. 

On pumpkin plants, male flowers have more pollen and female flowers have more nectar. The male flowers also tend to be more noticeable, sticking up above the rest of the plant. This is essential because a pollinator must visit the male flower first, collecting pollen then heading over to the female flowers where they get rewarded with nectar and facilitate fertilization with the pollen from the first flower.

It is possible (and often essential) to be able to tell the difference between a male pumpkin flower and a female pumpkin flower. Luckily, it’s easy enough if you know what to look for! Typically, the plant will produce more male flowers than female flowers. Male flowers will also develop first, with the female flowers developing a week or so later. The easiest way to tell is by looking at the stem of the flower. Female flowers are on thicker stems than male flowers. This stem is known as the peduncle. It has to be able to support the weight of a pumpkin if pollinated. You can also look at the anatomy on the inside of the flower. Male flowers have a single, long stamen that is pollen-bearing while female flowers have a stigma. 

Role of Pollinators in Pumpkin Cultivation

Because pumpkins do not self-pollinate, pollinators are essential to pumpkin pollination. There are many different types of bees that will visit your pumpkin flowers but a few make up a vast majority of pollinating events. Honey bees, squash bees, and bumble bees are some of the most common bees you’ll seed buzzing in the pumpkin patch. 

Like most other pollinators, bees need to be drawn to your garden to do what they do best. Growing a wide variety of native and non-native flowering plants in your garden will increase pollinator visitation rates, increasing the likelihood of your pumpkins being fertilized and growing big and strong. Keep in mind that full pollination is achieved after two to five visits to the same female flower. Fewer visits may result in that small or misshapen fruit we were talking about earlier. Bring on the bees! 

Challenges in Pumpkin Pollination

If you are noticing a poor pollinator presence in your garden or your other squashes are coming out small or misshapen, you may be facing a common challenge in pollination. Pollinator populations are declining all over the world as a result of habitat degradation and fragmentation, human-caused pollution, climate change, and the overuse of pesticides. You can do your part to combat this by keeping pollinator habitat alive in your garden.

Besides those issues, there are a number of other factors that can affect pollinator visitation to your garden. If you till annually where you garden, you may be disturbing ground-nesting bee populations, ultimately lowering their numbers in your garden. Overly cool or wet weather can also inhibit their travel, as can high winds. It’s also possible that your neighborhood bee population is more attracted to other sources of nectar flowering at the same time! Should these issues arise, fret not, as many growers practice hand pollinating their pumpkin flowers in order to ensure a bountiful harvest. 

Hand Pollination

The first step to hand pollinating your pumpkin flowers is to identify the difference between male and female flowers. Once you’ve mastered this, it’s easy from there! The male blooms produce a ton of pollen so this is where you’ll want to start. You can either use the flower itself (pick it off the plant and use the stamen as a sort of paint brush) or use another object like a cotton swab, paintbrush, or q-tip to collect the pollen and bring it to the female flower. You can brush it over the stigma at the center of the bloom and voila! Pollinated. From here, you can let nature do its work. Even if you aren’t necessarily observing a low pollinator presence in your garden, practicing hand pollination will ensure pumpkin production in your garden.

Pollinate Your Own Pumpkins Today:

Now that you understand pumpkin pollination, growing your own pumpkins will be a breeze! There are a ton of varieties to choose from - big to small, pie-types to carving perfection, and a wide selection of colors. Sow True Seed carries a range of pumpkin varieties and there is sure to be one that is perfect for your garden. 

Wildwood Pumpkin

The Wildwood Pumpkin has been saved by the Neely and Carroll families of Wildwood, Georgia for over six generations. Oral history places the origin of the variety with the Cherokee Indians who were present in the Wildwood area prior to their forced removal in 1838. This variety of pumpkin is pale orange on the outside and has bright orange flesh. It is generally round with light ribbing, but there is a good bit of variation - some have flattened cheese wheel shapes and others are taller upright fruits. These are excellent pie pumpkins! 

Jack-B-Little Pumpkin

The sweetest little pumpkins you ever did see. These only reach about three to six inches in diameter and have deeply ribbed, orange flesh. The vigorous vines produce eight to 20 fruits each and are excellent for eating as well as a delightful decoration in your home. 

Connecticut Field Pumpkin

This one is rumored to be the original Thanksgiving pumpkin and is now often used for carving. The Connecticut Field pumpkin produces 15 to 25 pound fruits with thin rinds and thick yellow-orange flesh.

Small Sugar Pumpkin

The Small Sugar pumpkin is exactly what it sounds like. These small, sweet fruits weigh six to eight pounds and are a beloved standard for pie makers everywhere. Dry flesh with no stringiness is what really makes this variety shine in the kitchen. 

Cinderella Pumpkin

With only the slightest imagination does this heavily ribbed, bright orange squash turn into Cinderella’s carriage! Also known as Rouge Vif d’Etampes, this highly ornamental French heirloom was said to be very popular at Parisian markets in the 1880’s. These pumpkins aren’t just for looks though, they also have excellent flavor and make great keepers. The bushy vines grow round and generally flattened 20 pound fruits. 

Dutch Fork Pumpkin

An original Cherokee heirloom, the Dutch Fork was once the premier pie pumpkin in much of the Carolinas. It has become extremely rare and has been stewarded by heirloom vegetable expert James Kipler and a handful of other folks in the Dutch Fork area of South Carolina for the last 100 years. This large, deeply lobed, round pie pumpkin with rich, sweet taste is a strong grower and an excellent keeper. 

Styrian Hulless Pumpkin

This one is a staff favorite! This hulless pumpkin is primarily grown for its protein-rich seeds but the flesh is also smooth and tasty. The seeds can be eaten toasted, raw, or pressed for oil. Styrian Hulless plants are prolific and fast-growing.

	Article Written by: Hannah Gibbons
	About the Author: Hannah Gibbons, an employee at Sow True Seed since 2020, has nearly a decade of experience in the agricultural industry. Their passion for environmental education and regenerative agriculture has been the cornerstone of their work, aimed at making gardening accessible to all.