Got Pollination Problems? Give Hand-Pollination a Try!

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Male and female flowers appear on a cucumber plant.

This well-pollinated cucumber plant is growing a new cucumber. The fruit comes from the female flower, pollinated by pollen transferred from a male flower, like the bright yellow one above. Ideally, pollen is transferred by bees, but if not, hand-pollination is an option.

If you’re having trouble with pollination of your cucurbit plants, don’t give up. Give hand-pollination a try.

Cucurbits (the family of plants including squash, cantaloupe, watermelon, pumpkins, and cucumber) are notorious for having pollination problems. A short botanical lesson reveals why. Rather than having male and female parts in one flower, like a tomato plant does, cucurbits have separate male and female flowers on the same plant. That means pollen must be carried from one flower to another (male to female) in order for pollination to occur.

Here’s a little more in-depth description of how cucurbits flower. The first flowers on a cucurbit are male, and these may remain on the plant for about a day before falling off. Sometimes, this falling scares gardeners, especially those growing squash, 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’s still blooming.

You can distinguish male and female flowers a few ways. The easiest way is to look at where the stem meets the flower. On a female, this area will look like small fruit. Male flowers are typically shorter, don’t show immature fruit, and often appear in clusters. Here are a few examples of male and female flowers on cucurbits.

First, a couple male flowers…

Bees take pollen from male cucumber blooms.

A bee found its way to these male cucumber blooms. The cluster indicates they’re male.

Zucchini plants have male and female flowers.

These are male flowers on a zucchini plant.

And now for some females…

Female cucumber flowers produce fruit when pollinated.

This is the female flower on a cucumber plant. See the immature fruit at the base, a clear indication of a female flower. This one has probably already been pollinated and the flower is starting to close.

Zucchini plants have male and female flowers.

This is the female flower of a zucchini plant. Due to good pollination, it’s producing a nice-sized zucchini.

Female flowers produce fruit on squash plants.

This female flower is on an acorn squash plant.

So here’s the trick. Cucurbits need cross-pollination from male to female flowers, but this requires a little more of nature, namely of the bees that pollinate our vegetables. If bees aren’t present for some reason (such as broad-spectrum pesticides being sprayed nearby or heat or rain keeping the bees under cover), then fruit either doesn’t appear or it appears small and shriveled up because it’s not well pollinated. At this point, human intervention is necessary. As we’ve been telling the many folks on the website who are seeing flowers but no fruit, you can try pollinating your cucurbits by hand. Here is a lesson in hand-pollination using my Straight Eight cucumber plant as our subject.

Use a paintbrush to pollinate cucumbers by hand.

To hand-pollinate a cucumber, dip a paintbrush into the center of a male flower. Some gardeners use a cotton swab instead of a paintbrush.

Pollen sticks to paintbrush bristles.

The pollen sticks to the bristles on the paintbrush just as it would stick to the hairs on a bee’s body.

Pollen transfer to the female flower from the paintbrush.

Transfer the pollen of the male flower from the paintbrush to the center of the female flower. That completes pollination by hand.

The method of hand-pollination shown above should work well for all cucurbits. You also can remove male flowers and touch the anther (in the center of the male flower) to the female flower’s stigma (also in the center), or shake the male over the female, to transfer the pollen.

For those of you with copious bees, congrats! (I am thankful to be one of these people at the moment.) For the rest of you, I hope hand-pollination helps you have a great harvest of cucumbers, melons, pumpkins, and squash. Happy growing!

29 thoughts on “Got Pollination Problems? Give Hand-Pollination a Try!

  1. Good morning, I am putting in my very first garden and so all of this is new to me. I’ve heard that if I plant several kinds of squash, they have to be more than 25′ apart to keep from cross pollination and spoiling all of the squash. Is that a true statement? Also, since I am putting some cucumbers to grow directly into a greenhouse where NO bees will be, will I need to hand pollinate all of them?

    • Hi Penny,
      Vegetables cross pollinate all the time. Yes, squash of the sane species will cross because they are insect pollinated. However, your squash will still be the exact same squash that you planted. If you saved the seeds of the squash and replanted those, you may see the fruit of the cross. Cucumbers and squash are both cucurbits and have to have insects to pollinate the flowers. With no insects, you will have to hand pollinate to get fruit. – Danielle, Bonnie Plants

  2. That darn worm gets in and destroys my zucchinis when they get ready to pick.
    How can I keep them out this year?

    • Hello Larry –
      Are you talking about pickle worms – that bore into the fruit? or the squash vine borer that bores into the bottom stem of the plant? You will find some pictures and recommendations here for the squash vine borer. I have had some luck using panty hose around the base of the stem to discourage the adult moth from laying eggs. For more on the pickleworm, this publication from Tennessee has great photos! – Danielle, Bonnie Plants

  3. hey, whats the best way to treat a squash plant for vine borers. also , i read where not to plant cant-elopes next to cucumbers, that it would make them taste bad, is that so.

    • Hi Dennis,
      Planting cucumbers next to cantaloupes will not make them taste bad. If your cucumber tastes bad it is because it was grown under stress which could be caused by high temperatures, dry soil, low fertility, or disease. If you notice the damage afterwards, you can always try and preform surgery on your squash plants. Squash vine borer adults are red and black moths that lay eggs towards the base of the stem. The eggs hatch and we all know what happens next. I have had pretty good luck wrapping the base of my squash plants in panty hose – discouraging egg laying. Great tips, here, from Ohio State University on battling the squash vine borer. – Danielle, Bonnie Plants

  4. Hi, Mary Beth

    I’m wondering if it’s possible to keep Cucurbits in a vegetative state, say indefinitely

    • Hi Sean,
      I’m curious why you would? Keeping it in a vegetative state would prevent it from flowering and fruiting. Is your goal to maintain leafy vines of cucurbits with no crop?

  5. Thanks for posting…with pictures! It is the best explanation of pollination problems and solutions for an amateur. I am going lemon cucumbers for the first time this year. Please continue your postings on other garden subjects. Your work is greatly appreciated.

  6. I just found hyour website -just as I was pulling out the tomatos because they had produced no tomatoes -and the cucumbers! Maybe next time.

    I guess I have a lot to learn and shall try again next year.

    The cucumbers had abundant flowers but no fruit -pollination… I harvested one cucumber, burpless tasted well but no more.

    • Hi Alejandro,
      So sorry to hear that you found us too late! Your tomatoes may have simply been taking a break in the heat — if you are experiencing extreme temps where you live. The hand pollination on cucumbers has kept a lot of gardeners busy this year. We need to plant many flowers and shrubs attractive to pollinating insects and bees, as they are essential for our garden’s productivity. Wishing you much success in the coming season. ~Mary Beth, Bonnie Plants

    • Ha, ha, April. Well, you know the saying…the early bird gets the squash (or was that the worm?)! If you have bees, you shouldn’t have much of a pollination problem. If not, just try to get up early enough that the flowers are still open…it doesn’t have to be before daybreak or anything. Happy growing! Kelly, Bonnie Plants

  7. Have zucchini squash that seems to only have male flowers. Is that even possible? There is absolutely no flower on these plants that even come close to looking like the female flowers or fruit. I had the same problem last year but wanted to try again this year. Plenty of bees in my garden and everything else seems to get pollinated but these particular plants. Very disappointed.

    • Hi Leslie,

      It’s not likely that your plant has only male and no female flowers. Check for the female flowers in the morning. They drop off fairly soon after flowering. You might also fertilize your plant to give it a boost. Use a fertilizer labeled for vegetables. I hope this helps!

      Kelly, Bonnie Plants

  8. Wow! I sure learned a lot about my squash, pumpkin, and cucumber plants. I was not sure about the male female flowers. I had no sign of fruit and poof there is a pumpkin growing! I see the light and I’ll be out there helping my community bees, since I lost a few squash. Thanks for all the wonderful information.

    I look forward to a fabulous garden later this year and next year!

    Annabananna of Arizona

  9. Hello! Iv got a pretty good garden growing. All from transplants. Iv got 15 or more watermelons, 9 or more cantaloupes, okra(4&5bushes) & vining cucumbers with no fruit yet?? There were flowers on them(4 plants)but didnt look good to see if male/female. Two plants died before flowers cam?? Now the two left dont look good(yellow,dry looking leaves) an no fruit growing. Not big plants either. Whats wrong??

    • Hi Audrea,

      Wow, that is a big garden! You must have lots of space to grow this many melons and cucumbers. It sounds like poor pollination, perhaps from the heat, has affected your cucumber plants. Have you fed your plants with vegetable fertilizer? And watered them well? If they are spaced properly and receiving sun, water, and nutrients, I am not sure what the problem could be. If you think it might be a disease or pest, send your question, preferably with a photo, to our Ask an Expert service. I hope this helps!

      Kelly, Bonnie Plants

  10. What about ants in the blossoms? I have a cantaloupe plant with lots of little black ants in the male blossoms.

    • Hi Candace,
      The ants are simply feeding on the residue of something else…either drinking water left in the blossom or following behind aphids. The ants are not anything to worry you. Happy growing! ~Mary Beth, Bonnie Plants

  11. Thanks for the information. This is good information for me. Plenty of female but no pollination.

  12. There’s also a product that is so much easier than that called Blossom Set spray. It works on tomatos, egg plant, cukes, squash. This “tricks” the plant into thinking its been pollinated and fruit develops. Just one spray does the trick.

  13. thanks! this must be the problem in my garden. there are plenty of bees around my yard, but they are always swarming the crepe myrtles.

  14. I have cucumbers planted they are vine plants about 6 feet tall, we had about 4-5 cucumbers early then nothing. The plant is covered in flowers. After reading your page I checked my plants and I do not see any female flowers with tiny fruit. Is it possible that the plants are only producing male flowers?

    • Hi Janice,
      Plants typically start with a flush of male blooms and then the female blooms with tiny fruit begin to appear. Since you have already had some of those bear fruit, it may just be taking a break if you are experiencing unusually hot weather. Be patient; those female flowers will come back soon. Look closely to find them and try your hand at pollinating them if you do not have many bees or pollinating insects in your area. Happy growing! Mary Beth, Bonnie Plants

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