Hand Pollinating Squash

A squash vine borer moth in Patty Leander's garden.  Photo by Bruce Leander

A squash vine borer moth in Patty Leander’s garden. Photo by Bruce Leander

Squash vine borers are just horrible in my part of Texas.  Because of this, it is almost impossible to get a great crop of any of the standard summer squash varieties grown in our area (yellow crookneck, zucchini or patty pan).  As I talk to people, I get more questions about how to control this destructive little pest than any other.  Quite frankly, if you are an organic grower, there is not much you can do to beat the borer besides growing your plants under row cover (if you are not organic, Sevin dust does a fairly decent job of keeping borers away, but it needs to be applied every four or five days).  If you properly grow under row cover you will definitely stop the vine borer.  However, you will also prevent bees and other pollinators from reaching the plants.  Because of this, if you want any fruit, you will be forced to pollinate your plants by hand.  Luckily, hand pollination of squash plants is very easy to do.

A female acorn squash flower in my garden

A female acorn squash flower in my garden.  Notice the small, developing acorn squash under the flower.

Flower Identification – Hand pollination of squash blossoms requires no special skills or tools.  All you have to do is be able to identify male and female flowers.  On squash, this is very easy to do.  Female flowers will always have a tiny fruit under the flower. 

Up close view of the stigma of a female acorn squash flower

Up close view of the stigma of a female acorn squash flower


Male flowers grow on a long narrow stem.  You can also tell the two apart by looking at the reproductive organs found in the center of the flower.  The female flowers contain the stigma.  The stigma generally looks like a flower in its own right.  It has several “bumpy structures” that cluster around a central opening.  Anthers (male parts) look a lot like the thing my wife uses to apply eye shadow.

Up close view of the anther on this male squash flower

Up close view of the anther on this male squash flower

The long narrow stem and abscence of fruit identify this as a male squash flower

Hand Pollination – When growing under row cover you will need to pollinate as soon as the flowers begin to open.  When this happens, roll back your cover and find a male flower.  Cut it off where the flower stem meets the main stem of the plant.  Next, gently remove all of the petals from the flower.  Once the petals are gone you are left with a stem and exposed anther that is about 4” to 6” long. 

The anther and stem of the male plant will be used to "paint" the pollen onto the stigma of the femal

The anther and stem of the male plant will be used to “paint” the pollen onto the stigma of the female

Now find a female flower and use your stem and anther to “paint” the stigma in the center of the female flower.  Gently rub the anther over the stigma a few times.  Then go on to the next female flower.  Each anther can be used to pollinate approximately five flowers.

"Painting" the stigma

“Painting” the stigma

Caution – A fellow gardener once told me that they were crushed to find a vine borer trapped under their row cover after they had hand pollinated.  If this happens to you don’t worry.  While it is best if you can keep your squash plant bug free for its entire life, a mature squash plant can usually “outgrow” a worms infestation if the eggs are not laid until after pollination occurs.  Because of this, many gardeners that grow under cover often remove the cover completely when the pollination is done.

If you want to keep the cover on throghout the life cycle, work with a buddy and pollinate in the late afternoon (borers are most active before noon).  Roll back the cover and quickly harvest several male flowers.  Put the cover back in place as you strip the petals from the male flowers.  When you have all of the anthers exposed quickly pull the cover back and pollinate all of the female flowers at one time, then quickly put the cover back in place and anchor the sides to the soil. 

Squash being grown under cover in Patty Leander's garden.  Photo by Bruce Leander

Squash being grown under cover in Patty Leander’s garden. Photo by Bruce Leander

This method of hand pollination is a great tool to master and you can use it for all of your cucrubits.  If you do it right, I am convinced it will increase your yields  This fall I grew acorn squash.  Since we have been short on bees, I did a small experiment.  I hand pollinated half of my vines and let nature pollinate the other half.  I got almost a 100% yield from the flowers I pollinated.  Mother Nature was only successful about half the time.

28 thoughts on “Hand Pollinating Squash


  2. I am going to have to hand pollinate my acorn squash varieties because we have no bees. I have several female blossoms. How long does it take for them to open on their own…I have read that some people have to force them open to pollinate and I don’t want to miss my chance. However, I don’t want to rush it either.

    • I have never heard of forcing them open. In fact I would be leary of that. they open when the ovary is ready to be fertilized. I would think forcing them open would be rushing nature and I would not expect to get good results. Once you see the bud showing yellow you can be fairly certain they will open in the next day. You do need to watch them but you have plenty of time. They are fully open and fertile for a full 24 hours (or more). Just keep an eye on them. They do move fairly fast.

      • Thanks for the reply! I have been checking every morning and was able to pollinate a watermelon. However, my female squash blossoms were not opening and on further inspection early this morning, I found pickle worms…lots of them. There were tiny holes in many of the female blossoms so I snipped them and found a pickle worm inside. Is there any hope? I. Am allergic to pesticides so I have to keep it organic. I spray azamax but I don’t think that works on pickle worms.

        • I don’t use pesticides either. Unfortunately though, pickleworms are bad news. Even with pesticides they are hard to control. If you have other cucurbits, check them too. If they are unaffected, you could sacrifice the squash and hope the bugs keep eating the squash and don’t move on to the melons or cucs.

          • My acorn, butternut, buttercup and zucchini squash are doing great as plants. however the acorn squash, which have lots of male flowers,do not have any female flowers. I have already harvested some zucchini squash and there are lots of butternut squash (about 1/2 dollar size) on the vine. So far I have not had any problems with SVB’s but I changed my methods of controlling them this year. Last fall I applied liberal amounts of Ortho Bug Be-gon Max and 20-20-20 fertilizer and rototilled it in. I did the same thing here in March and then again in April before planting. Also changed the location of the squash plants. I always plant buttercup squash as they are resistant to SVB’s as their stems are to hard for them to bore into. I will just wait and see on the acorns, but here in OK there should already be some on the vine.

  3. Pingback: Central Texas Gardener Blog » Blog Archive » Catching rain, aquaponics, squash pollination & nematode control

  4. Does anyone have a good solution for getting rid of chiggers?? I have tried all kinds of sprays and nothing works. I finally have resorted to spraying myself with Deepwoods Off. I usually spend time every morning in the vegetable garden. usually around the squash plants-that seems to be where they hang out.

    • I hope you get some responses. According to my mustang grape harvesting friends this is a very bad year for chiggers. When I was a kid my dad kept a sock full of sulfur dust by the door. Every time we went out we dusted our legs with it. Also when they were bad we would make a cuff in the bottom of our pants and put sulfur in their. Didn’t stop them all but it helped

  5. I already have many buttercup squash weighing about 5/6 lbs. This hot OK sun is scalding them. I can just pierce the skin with my fingernail.When is it ok to harvest them, or should I just let them sit there longer. thanks

    • If you are worried about the heat I would add a little afternoon shade with a tarp or something. I would leave them on vine until you can’t get your fingernail into them. To me, unripe winter squash just don’t tast that good.

      • OK-I will try to rig something up. Problem is they are scattered over a 40′ area, but I will come up with something. Thanks for the reply.

  6. I’ve been growing Buttercup Squash up in Washington, about 1,800 elevation, on the southwest corner of Mt. Rainier National Park. I’ve been hand pollinating my Buttercups for many years, and have been somewhat successful. I need to have the squash plants on the south side of my shop, and need to water most days. I know this isn’t ideal territory for squash, but I have a lot of fun. So far I have about ten growing from two inches across to almost four inches across. Wish me luck. Thanks for the other information also.

    • Thanks for the great comment. Your timing is awesome as I am actually looking at Rainer right now! Visiting my daughter in Seattle right now. How lucky you are to live in such a beautiful place!

  7. I have just read about Bakers Creek and have requested their catalog. They have several moschata variety of winter squash. These are usually completely resistant to squash vine borer’s. On a separate note, I have just harvested about 15 good size buttercup squash.Some were 5/6 lbs.They also freeze very well. I think they are the best for baking-very sweet and not stringy at all. We have been blessed here in OK with a moderate summer so growing conditions were very good.

    • Congrats on the squash harvest! You are the second person this month that grew buttercup squash. I have never tried that one. I will have to give it a try in the spring!

  8. On the male flower it seems there is no pollen on it to be transferred to the female flower… how can I tell when the pollen is there so I can manually pollinate for my butternut squash?

    • Touch it to a white hankie or Kleenex. You should see some pollen transfer to the cloth. Even if the bees have been on it, there should still be enough pollen left to fertilize the females.

    • I have heard that you can open the flowers. I have always been lucky enough to have both types of flowers open at the same time so I have never personally done that. If it were me, I would find some way to do a test; like tie a ribbon around the vine close to the flowers you pollinate with opened flowers. Then I would compare the results to the ones you pollinated from flowers that opened naturally. I would be very interested to know your results. Please let me know how it goes.

  9. Well the new season is here and so far the garden has been amazing. Tomatoes already 4-6 ft high and loaded. I have already picked zucchini and yellow squash-egg plants are next then the cukes.
    Question: I can never get beets or carrots to grow. Potatoes are the only root crop that I have luck with. I till in about 3″ of mushroom compost each spring to make sure ground is loose and not packed. Also use Miracle grow vegy fertilizer every 2 wks. My fellow down the street have fantastic luck w/beets & carrots, so it is not the weather. Any suggestions would be really appreciated.

    • I wouldn’t feel to discouraged. I have found that no matter how good a gardener you are there is always something you will have a problem with. Beets are one of the vegetables that I have had trouble with. Some years they do ok and others not so much. Last year I read that the trick to beets was to keep them evenly moist through out their growing season. According to what I read, if the soil gets too dry beets will stop growing completely at that point and never recover. After reading that I decided to work hard and keep the soil moist all season. It did appear to help. I did have bigger beets this year.

      Another thing I have learned with carrots and beets is not to over plant. This is a bit easier to achieve with beets as their seeds are so large. However with carrots I used to plant heavy and then thin. I am now convinced this is a bad practice. Last year I took more time planting individual seeds about 3″ to 4″ apart. I think it helped. Another thing I have learned with carrots is finding the right variety for your area. My soil has a lot of clay. Because of this, no matter how much compost I add to it, it is still very hard and sticky after the first 3″ or 4″. Because of this I do not try and grow long carrots. I typically grow Danvers. It is a nice mid-size orange variety. I also like Atomic Purple and will occasionally grow a red, white and blue mix from Burpee’s.

      Finally, I would cut back on the fertilize to no more than once a month. In fact, all of that compost you are tilling in may be providing enough N on its own. Too much nitrogen in the soil encourages root crops to produce tops and not bulbs. In cases like this I like to do experiments. If you have the room I would grow one set of plants with the fertilizer and one without. Lots of luck and please let me know how it goes.

      • Thanks for the info. I will plant some beets and carrots ( 1/2 Danvers) later this summer and see how they do. As for the beets, I think that is probably just what happened. My soil, while very loose, tends to dry out quickly here in the OK sun. Like today is going to be 91. I will keep you appraised.

  10. Jay: I have found a new butternut squash. It is Pilgrim Hybrid, a restricted vine variety. It is still a mushata so no problem with SVB’s. I plan on trying it next spring and wondered if you are familiar with it. The seeds are sold by Burpee and ToddSeeds. This squash is supposed to be better tasting and creamier than the standard, plus it will not take over the whole garden. Thanks, Dick Lovett

    • I am not familiar with it but I went out and read up about it. Really sounds like a winner. In fact, I may have to try it myself. I like the idea of 3 foot vines. My vine garden was so out of control this year. I will appreciate something that is a bit more manageable! Thanks for the tip!

      • Jay-I found the same thing by Burpee It is called butterbush. On line the seeds cost almost $10 w/ shipping, but I found them at lowes, as they always carry Burpee seeds, for $2.89. Big difference. Thought I would pass that along to you, Dick

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