How to pollinate watermelons?

Hand Pollinating Melons – How To Hand Pollinate Melons

Hand pollinating melon plants like watermelon, cantaloupe and honeydew may seem unnecessary, but for some gardeners who have difficulty attracting pollinators, like those who garden on high balconies or in high pollution areas, hand pollination for melons is essential in order to get fruit. Let’s look at how to hand pollinate melons.

How to Hand Pollinate Melons

In order to hand pollinate melons, you need to make sure that your melon plant has both male and female flowers. Male melon flowers will have a stamen, which is a pollen covered stalk that sticks up in the center of the flower. Female flowers will have a sticky knob, called a stigma, inside the flower (that the pollen will stick to) and the female flower will also sit on top of an immature, tiny melon. You need at least one male and one female flower for hand pollinating melon plants.

Both male and female melon flowers are ready for the pollination process when they are open. If they are still shut, they are still immature and will not be able to either give or receive viable pollen. When melon flowers open, they will only be ready for pollinating for about a day, so you need to move quickly to hand pollinate melons.

After you make sure that you have at least one male melon flower and one female melon flower, you have two choices on how to hand pollinate the melon flowers. The first is to use the male flower itself and the second is to use a paintbrush.

Using a Male Melon Flower for Hand Pollinating Melons

Hand pollination for melons with the male flower starts with carefully removing a male flower from the plant. Strip away the petals so that the stamen is left. Carefully insert the stamen into an open female flower and gently tap the stamen on the stigma (the sticky knob). Try to evenly coat the stigma with pollen.

You can use your stripped male flower several times on other female flowers. As long as there is pollen left on the stamen, you can hand pollinate other female melon flowers.

Using a Paintbrush for Hand Pollination for Melons

You can also use a paintbrush to hand pollinate melon plants. Use a small paintbrush and swirl it around the male flower’s stamen. The paintbrush will pick up the pollen and you can them “paint” the stigma of the female flower. You can use the same male flower to hand pollinate other female flowers on the melon vine, but you will need to repeat the process of picking up the pollen from the male flower each time.

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Hand Pollination of Watermelon Flowers

Why on earth would you have to resort to this? Most people with proper gardens don’t have to or if they do, they do it because they save seeds and want to prevent cross-pollination. But on a balcony, particularly one high in the air, you’re creating a somewhat semi-enclosed eco system that is missing something crucial for the reproduction of many plant species: insects.

Some plants produce flowers that incorporate both male and female parts and are easily able to reproduce on their own. Tomatoes and Peppers are two such plants. They produce what are known as “perfect” flower and all they need to reproduce is a good shake that they can get from a stiff breeze. But in the case of plants that have separate male and female flowers, such as melons or squash, the pollen has to be transferred from one flower to the other via a pollinator. In some cases, the wind can accomplish this but most plant species rely on insects and the one insect most successful at pollinating flowers is the bee. Bees collect both nectar and pollen – sometimes more of one than the other depending on what’s going on in their hive. When they visit a flower, pollen tends to “stick” to their little hairy bodies and is carried with them from flower to flower.

Male flowers tend to be more plentiful than the female flowers.

It is easy to tell the difference between the male and female melon flower.

I don’t get very many bees on the balcony. Certainly not enough to guarantee that the half dozen female flowers on my lone watermelon plant that only open for one day will get pollinated and turn into melons. So I take matters into my own hands.

First thing to do is know the difference between male and female flowers. Males have a stamen which consists of an anther connected to a filament that emanates from the base of the flower. Female flowers have a pistil which consists of an ovary at the base of the flower that extends along a tube like structure know as a style up to the stigma at the end of which is the receptor for pollen from the male anther. It is the ovary at the base of the female flower that will develop into whatever it is the plant is suppose to produce. And it is the anther on the end of the stamen that carries the pollen needed by the ovary to turn into a fruit.

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Female watermelon flowers don’t open for very long so it helps to identify them as soon as they appear and be prepared to service them as soon as they are ready. This is typically a one morning affair. When I inspect the plants in the morning and spot a female flower open, I pull off an open MALE flower. Make sure you don’t pull off a female by mistake! Don’t bother with flowers that look like they are about to fall off or aren’t quite open yet. You need flowers that look like they are at their peak: males loaded with pollen, females fully open. With the male flower off the plant, pull off it’s petals. I do this to expose the anther which should be loaded with pollen.

You can pull off the male flower petals to expose the stamen, coated with pollen.

Hand pollination is a simple matter of uniformly transferring the pollen from the male anther to the female stigma.

A week after pollination – the beginning of a new watermelon.

With the male flower prepped I carefully wipe what is left of it across the center of the female flower. I try to get pollen all over and around the stigma. Take your time, do a thorough job and do your best not to damage the female flower. If there are more than one suitable male flowers open, grab them and repeat the process on the same female flower. The more the better. That female flower is going to close up tomorrow so you might as well make use of those ready males while they are around.

If all went well, in the case of watermelons, you should notice a big change in the female flower within a few days. The stem attaching the ovary to the vine will thicken and elongate and the ovary will start pointing downward. It will start to get larger at a surprising rate as it turns into a melon.

On my vines I try to get no more than two watermelons per plant. But if you have multiple female flowers ready for pollination, don’t hesitate. This is not a sure fire way to guarantee pollination and don’t be alarmed if some of your attempts fail. If you end up with too many developing melons, pinch off the weaker ones and concentrate on two or maybe three provided you can supply the plant with the nourishment it needs to support that much fruit.

If you’re interested in saving seeds, hand pollination may be the only way you can ensure the seeds from one plant truly represent that plant variety. But you need to do more than just hand-pollination to ensure this. You need to put up some sort of barrier around the pollinated female to prevent stray insects or a good breeze from contaminating the female with pollen from a different flower species. Amy Goldman’s books “Melons for the Passionate Grower” and “The Compleat Squash” give fairly thorough accounts on how she hand-pollinates plants in her garden.


Beekeepers in the Pacific Northwest are not blessed with the high honey yields of beekeepers in other regions of the country. They are more reliant on renting their bees to pollinate crops and fortunately the agriculture of the PNW has a variety and abundance of commercially grown crops that require or benefit from honeybee pollination. In our work as the PNW Tech Team, Ellen and I are fortunate to work with our beekeepers and sample their colonies while pollinating many different crops in the region. This is the first installment of a series of ‘Crop Pollination Profiles’ where I’ll outline the basics of cultivating each crop and the role the bees play.

Watermelons are widely grown near Hermiston in Eastern OregonColonies pollinating watermelons near Hermiston, ORYoung watermelon plant growing through plastic mulch

Watermelon (Citrullus lanatus) is a vine-like annual in the Cucurbit family with cucumbers, squash, gourds and other melons. It favors an abundance of sunshine, warm nights and loose, well-drained soil.

Melons require a good deal of water and grow well in sandy/loamy soils with the aid of irrigation. Watermelons are commercially cultivated in raised soil rows with individual plants being spaced 2-3 feet apart with 5-8 feet between rows. Typically black plastic mulch with drip irrigation underneath is used to facilitate ideal growth conditions. The plastic sheeting provides several benefits including, increasing soil temperature, moisture retention, and weed control.

Watermelon rows alternating with rows of wheat for windbreak

Often a cereal crop (e.g. wheat) is inter-sown between melon rows to provide windbreak and protect young plants.

Female flower with visible ovary

Watermelon plants are self-fertile and bear separate male and female flowers on the same plant. Flowers are approximately 1-inch in diameter and range from pale to bright yellow.

Forager on male flower

The pollination window is drawn out over a few months with plants producing a new flush of blooms after picking mature fruits. Hired colonies are required for longer than most crops with colonies being placed in fields from late May until early September. Pollination rental rates are in the range of $60-$70/colony. While the overall bloom of a field is drawn out, individual female flowers are only receptive to pollination for a single day. Flowers open early in the morning and close by the afternoon with peak pollination occurring in mid-morning.

Proper pollination is essential to achieve well sized symmetrical fruits. Colonies are stocked at 1.5-2 colonies/acre depending on grower preference. Bees can forage pollen and nectar from watermelon but the flowers aren’t particular attractive if alternative forage exists nearby. Watermelon pollen is bright yellow and the photo below shows the lack of alternative forage available to bees in this field.

Pollen trapped from colonies in watermelon fields showing low diversity of forage available

Due to the relatively low flower density, limited amount of pollen and nectar available, and extended duration of pollination bees may require supplemental feeding while in watermelons to remain in robust health.

Cantaloupe problems.

The most probable cause for the problem you are describing is related to pollination. Cantaloupe has female flowers as well as male flowers. Transfer of pollen by bees from male flowers to female flowers must occur in order to have fruit. Environmental conditions as well as nutrient imbalance can influence fruit set. Hot temperatures and/or high fertility may cause only male flower production thus no fruit set. On the other hand, cool and rainy conditions will impair pollination resulting in poor fruit set resulting in abortiveness of the fruit and early drop.

Often times, diseases and/or insects can lead to cantaloupe fruit to turn color and drop off. Root knot nematodes could stress the vines resulting in proliferation of blooms but no fruits. Crop rotation with kale, cabbage, mustards or marigolds is helpful.

The other issue is with micro nutrient deficiency, primarily lack of boron. Boron is essential for pollen germination and pollen tube elongation and penetration greatly influencing the fruit set. In case of incomplete pollination, where the fruit set has not been successful, the fruit may start to form than soon after turn color and abort.

And the mistakes I’ve made, SO FAR.

Here’s what I did wrong. I’m going to be happy that this list, as far as I’m aware, is short.

1. I grew cantaloupe from the seeds of store-bought cantaloupes. To be fair to myself, I didn’t know any better! So don’t do the same thing — sure it’s tempting, but hybrids, if you bought one from the store (most of them are hybrids, apparently), will give you heartache or at least some stress. Read on to find out why. To those I gave seedlings, I will report my findings as I find them out, and I greatly apologize for any grief you experience!

2. I took a picture of the giant grasshopper, and it got away. I’m still kicking myself about this one, and it only happened yesterday. The babies are hard enough to catch. If you see a big one, don’t try to capture the awe in regards to its size or even impressive markings. Just kill it. It will eat and make babies. Something eats bits of my corn, and I blame him. Or them.

Here’s what I’m doing right (again, as far as I’m aware). Top-Ten List! Top-Ten List That’s Really in No Particular Order!

10. I gave my cantaloupe seedlings a raised bed and trellis in which to grow to their heart’s content without getting trampled by dogs.

9. I learned about square-foot gardening and went ahead and spent the big bucks to give them a good soil in which to grow. Even the in-ground pumpkins got a healthy dose of compost mixed into their soil spots.

8. I lovingly give them water each day, and I know to hold back on water as fruit maturity begins to happen.

7. I learned the difference between male and female flowers and what “self-fertile but not self-fertilizing” plants are.

6. I learned about and am quite willing to help my cantaloupes’ pollination. I don’t have many bees here yet, so I have to do what I can to help (I did see one of those big black ones this morning, but he didn’t linger long at the cantaloupe flowers; I also see an occasional sweat bee).

5. I check them each day for bugs and kill anything that looks menacing. Unless it gets away while I’m taking a picture, that is…

4. I’m being a good mom by growing the cantaloupes at my son’s request, and along the way I get to teach my kids about plant life cycles and good gardening practices (and/or my mistakes!).

3. I gently guide the cantaloupe vines up the trellis to give them something to hang on to.

2. I learned about companion planting and put in marigolds and corn in their raised bed.

1. And most importantly, I love them and talk to them and love them some more!

And there you have it. I’m so excited to have thriving cantaloupe plants, but I’m worried that I’m growing a hybrid. So I’m seeking words of wisdom from the experienced cantaloupe gardeners out there! And Cat at AmloFarms has some blooming male flowers (from REAL seeds) she can share with me for pollination purposes. This cantaloupe thing is getting pretty complicated, haha. But for the sake of my cantaloupes, I will drive across town and back! Thank you, Cat!

The cantaloupes are happily growing up their trellis and trying to grow out wide, too.

We’ve had male flowers for awhile, and today (day 38) I found my first female. Here’s how you tell the difference. The easiest way is looking at the flower stem.

The male rises from the vine with a single plain stem of its own.

The female has a cute little bulge that will become the fruit if pollinated.

Here’s a baby female bud.

You can also tell the difference by looking at the inside of the bloom, but here’s where I’m unsure about the condition of the inside of my cantaloupe blooms. The male stamens will have pollen, but I can’t tell whether mine do, haha.

And the females will have their stigma ready to receive pollen. But mine look quite green, so I don’t know if mine look the way they should (I’ve seen pics with them yellow).

All the same, I did my best to get some pollen from the male to the female. At first I tried q-tips and a paintbrush, but I saw hardly any yellow on either. So I finally pulled off some male flowers and exposed their stamens and rubbed them on the female.

No idea whether any pollen grains stuck.

So experienced cantaloupe gardeners, should I be seeing lots of yellow pollen on the males? The male pumpkin flower (just saw my first two today!) has a lot of pollen, that’s for sure. And ants. First blooms, day 38.

Here’s one of the giant plants. They have a long way to go to reach full size. Egads.

From what I’ve read, if I read correctly, the female flowers should be ok and just the males might be sterile. But I don’t know whether the females are sometimes sterile, too. And even if pollination happens, will I get a regular cantaloupe out of it or some dud?

And while I’m asking, let me ask this: Can someone identify this red bug for me? The bigger versions of it are black, but I don’t see any of those on the garden yet, but last fall I had a ton of all sizes in a bunch of fallen leaves. Even the people at Natural Gardener couldn’t name them for me. I kill them when I see them now. But I’d like to know what they are. They are not tiny lady bugs, that’s all I know.

In other garden news, I decided to do something with my broken tools. Please tell me this looks like a flower, because it’s supposed to, HA! I will probably paint it at some point, but it’s growing on me (hehe) as is, too.

You can see the evil chinaberry in my very nice neighbor’s yard behind it — it’s been my nemesis for many a year. My neighbor finally had it cut down several months ago, but the workers left the stump and roots, so of course it’s been growing back with a vengeance. We cut it again just to prevent seeds and it’s back — so the neighbor is getting the tree people back out to properly kill it. Not sure they’ll succeed if they don’t get the roots out. I’m having to close my eyes and ears about the herbicides they’ll probably use… But I’m so thrilled to have a neighbor who is trying to help with the invasives problem!

Sugar pumpkins continue to grow and confuse me. They just aren’t eager to send out tendrils, but growing they be, with new bloom buds forming.

Marigold seedlings! Only about 6 took, but I have more seeds to try with.

And much of my corn is happy. A few seedlings are getting chomped by something <evil eye at grasshoppers, even if they aren’t to blame>, but the rest are growing. I never really realized how beautiful a corn plant is until all this growing stuff.

And I’ve planted 8 pole bean seeds so far. I’m making use of the far corners of the trellis squares (ok, according to square-foot gardening, those squares belong to the cantaloupes but they were just sitting there empty! seemed so wasteful). I’ll be planting more along the fence once I amend the soil. My wonderful oldest son dug out the weeds from that area for me this morning. This whole “raising kids to work on the farm” was a brilliant plan of the pioneering farmers!

I planted Black-Seeded Blue Lake Pole Beans. The seeds look like engorged ticks. Don’t they sound wonderful? But I hear they are delicious. No, really. Really!

And we had another frog in the dog pond. Not surprisingly, he’s just as cute as Murray! Pictures soon!

Pollination Problems With Cantaloupe, Cucumber, Pumpkin, Squash and Watermelon

These plants are all part of the Cucurbits family and all have problems when it comes to cross-pollination. This is because where most plants have flowers with male and female parts in one flower, these plants have separate male flowers and female flowers. Often the window for pollination is short and when there is an absence of pollinators, the window of opportunity is missed. Pollen must be carried from the male flower to a female flower.

What creates the absence of pollinators?

Bees and other insects can be pollinators as well as the wind. Spraying insecticides in the morning or middle of the day can kill or chase off the bugs and bees that are so critical for your garden. Spray insecticides during the evening, after the bees have left for the day. This will give time for the insecticides to dry before they show back up. Also be sure that your garden is in a nice sunny location where there is good air circulation. This helps with cross-pollination as well as reducing the chance of diseases.

An absence of flowers in the area will keep bees away. Planting beneficial flowers will help keep the bees in the area. Plant flowering plants in your landscape or simply plant wildflowers near the garden area to encourage bees.

Male and female flowers look different. The female flowers are the ones that produce fruit and they will be the ones with a small fruit attached to the bottom of the flower. If you are having pollination problems, you can hand pollinate the plants by dabbing a small paint brush inside the male flower to collect its pollen and then dabbing it inside the female flower.

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Growing Pumpkins

Using annual ryegrass as a cover crop for your garden

Difference Between Hybrid, GMO and Heirloom Vegetables

Choosing the Right Onion for Your Garden

Amending Different Soil Types

Growing watermelon

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