Hand-Pollinating Zucchini Flowers
We had some problems this year with getting zucchini fruit to set. They would grow OK for a while, then shrivel up, rot and drop off the vine.
The problem is that the fruit are not getting pollinated. This job is normally done by bees, but for some reason this year they’re not doing it. I don’t know why – we still see plenty around the garden. Strange.
So, I’m reduced to doing the job of the bees by hand-pollinating the zucchini flowers.
The basic idea of hand pollination is to transfer pollen from a male flower onto the female flower. This causes the seeds in the immature fruit to become fertile, and so it grows to maturity in order to perpetuate the species. If the seeds aren’t pollinated, the plant isn’t going to waste energy growing a non-viable fruit. It just withers and drops off, and the plant tries again with a fresh flower.
The best time to pollinate is in the morning, when the flowers are fresh and just-opened. Later in the day the heat starts to wilt them and dry them out.
So how do you know which flower is which?
The male zucchini flower has a normal stem, and a single pointy bit inside it (the stamen) covered in dust-like pollen.
The female zucchini flower has a small fruit (ovary) behind it instead of a stem, and a more complex internal structure (the stigma).
Some people use cotton swabs or artist’s paintbrushes to transfer pollen, but I’ve found the simplest way is to simply pick the male flower (don’t pick the female flowers!), peel off the petals, and use it like a paintbrush to dab pollen onto the stigma of a female flower. Quick and easy.
Update: I’ve posted photos of hand pollinating pumpkin and squash flowers, which is a very similar process.
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I do not believe that heat has nothing to do with the flowers closing (at least I have not read anything to this effect). Different types of cucurbits will close open and close their flowers at different times. Although I am not quite sure what the trigger is for each plant. For instance watermelons will often open their female flowers later in the day although their male flowers will be open all day.
My morning garden routine always consists of pollinating members of the curcurbitaceae family, with the only exception being cucumbers which get pollinated very well by other insects. I even hand pollinate watermelons which can be a bit tricky.
Another trick I have used for years is that when there are no male flowers from a zucchini, I will use the male flower from a button squash or pumpkin (and visa versa). Now if you were going to save seed from that female plant this would not be a good thing to do. But to get the fruit to set, it works extremely well.
@Jason: Good tip on using squash or pumpkin flowers to pollinate zucchini! I had wondered if that would work, but hadn’t tried it. I assume it works in the reverse as well, using zucchini to pollinate pumpkins?
Thank you for this information. Possibly the problem we had a few months ago before we gave up and pulled out the plant.
I would not pollinate true pumpkins using a male zucchini flower. The main reason for that is that pumpkins are left to fully mature. Using pollen from different plants can change the end result. However with plants such as zucchini and button squash, the fruit is used immature. Thus there is no significant change in the fruit before it is picked.
I have used butternut squash to pollinate Kent/Jap pumpkins and visa versa. But I make sure that I note which ones I did this with and not save the seed from that fruit.
Back in Wollongong we pollinated a zucchini with a butternut squash. I let the fruit mature and that really seemed to mess up the zucchini plant (it kinda died after that). We called the end result a zuckin, but I have no plans to repeat this experiment.
@Gustoso: We didn’t have much luck with the last lot of zucchini and cucumbers we planted. I’m pretty sure it was due to lack of pollination – they were in a spot I didn’t get to much, and I had assumed that the bees were taking care of things for me.
@Jason: Thanks for the follow-up info!
I had to do the same thing in my area with the zucchini this year. Only the females that I hand pollinated actually grew to a decent size. The bees avoided them and the pumpkin patch like the plague. I had to hand pollinate the butternut and golden nugget pumpkins with this method as well. Same as your case, plenty of bees around, but they were more interested in the citrus and other flowers.
Gav
@Gavin: Yes, we had the same with our butternuts too. It was driving me crazy seeing all the pumpkins drop off the vines. By the time I twigged that I needed to hand pollinate, we only got about 6 pumpkins. Still, they were great!
Have you had to hand pollinate your zucchini flowers before? I ask because I have heard there has begun to be a shortage in bees and I was wondering if that had anything to do with it.
This is great information. I only have a few plants so I am a beginner gardener. I never heard of hand pollinating.
Thank you for the great post!
@Kate: I have hand-pollinated a bit before, but not really as a routine. We were a bit more half-hearted with previous zucchini-growing attempts
. We did get fruit though, so the bees must have been doing some work! We have a hive in the park near our house, and I see bees around the garden, so I know they exist in this area. In previous years we’ve grown sunflowers etc, and we didn’t plant them this year, so maybe we’re just not attracting as many bees to our yard at the moment.
I got no pumpkins and very few zucchini this year, wonder if it was because I had pulled out the overgrown lavender which was always covered in bees in the past. Are you actually growing zucchini at the moment or are those photos from the summer?
Darren, when I’m reading your post, it sounds like you’re the botanical lecturer in the university! Good presentation with beautiful pictures here.
By the way, I normally used the Zucchini to make the “Zucchini pickles”, it tastes really good!
@Greenfumb: No, I’m actually still growing zucchini, although those photos were taken on April 7. I planted these ones quite late, but they’re doing well and still producing. I’ve never grown them this late before, but I think that’s just because I’ve never tried!
@Wilson: Hehe, glad you found the photos helpful
. Do you have a recipe for your zucchini pickles?
[...] Change has an excellent illustrated post on hand pollinating zucchinis. This could have been the reason we only got one zucchini a few months ago. If only I had known! [...]
Hi again, I’ve linked to this post in our recent gardening update.
http://gustoso.wordpress.com/2009/05/24/rain-rivulets/
Hope you don’t mind and let me know if you want anything changed.
@Gustoso: Thanks! Looks great to me. Better luck next time with the zucchinis – and let me know if hand pollinating helps.
Absolutely, Darren. I’m love to share the pickled zucchini recipe with you! Check out this page: http://www.cookography.com/2008/pickled-zucchini-the-zuni-cafe-way
PS: You can skip the ground Turmeric powder, if you cannot withstand its exotic taste!
@Wilson: Thanks! I’ll add it to my list of recipes to try out.
I’m growing zucchini for the first time in a planter on a second floor balcony. I have carpenter bees – do you think they’re enough to pollinate the flowers, or should I hand pollinate? I know the carpenter bees are around because they leave their little piles… and my plants just started blooming this past week. Looks like 3 male flowers and 2 female flowers so far (at least the orange bits – there should be more coming.)
@Merle: I’d be hand pollinating anyway, just to be sure. You can’t really tell if the bees are doing their job until you’ve lost a few zucchinis, by which time it’s too late. It really doesn’t take any effort.
I’ve grown zucchini successfully for several years in a 8×12 greenhouse (I’m in northern BC where we had -4 C May 15.. it’s hot +28 C now though) however this year I have a pollination problem that I can’t yet solve by hand. All 6 of my zucchini plants are producing female flowers (one opens every day or 2) but NONE of the male flowers have opened yet.. so all the zuchinis fail to develop. Does anyone know what affects the male:female flower ratio of zucchinis? The plants seem healthy: big leaves, lots of flowers coming, etc I fertilize with a granular low in N (11 – 20 – 25 or close).
@Kerry: I think I read somewhere that pumpkins and zucchinis sometimes produce more of one type of flower (males?) when they’re young, and more of the other as they get older. Perhaps sowing in batches, each offset by a couple of weeks, might help? It’d also help prolong your harvest.
A quick Google has turned up lots of theories for having more of one type of flower than the other – lack of calcium, air/soil temperature, overwatering, not enough fertiliser, genetic anomaly, etc. I don’t know if any of them apply.
While you’re waiting for the males to show up, you can pick the unfertilised fruits while they’re still young, and fry them with the flowers on. Perhaps even with a tempura batter or breadcrumbs. You can also stuff the flowers with meat or ricotta. Yum
.
I have a silly question, I am in SE Pennsylvania, and it has been really wet, and damp for June, my zucchine are sprotting male flowers only, my question, does one plant produce both male and female?????? thanx
@Regina: Yes, normally both male and female flowers sprout from every zucchini plant. Sometimes weather and other factors seem to cause flowers of only one type to be produced, although I’ve never found a good description or what can cause it. You can eat the male flowers while you wait for some females.
After about 3 weeks of female-only zucchini flowers (6 plants), I finally have male flowers opening! Whew.. finally some pollination.. Things will go OK now. The one yellow variety (I have the name, but not with me) has produced 2 male flowers, both without pollen, but there is enough from the greens to go around. I’m a beekeeper and use “bee-sticks” to pollinate: I pick up a few freshly dead bees from in front of the hive, mount them on a toothpick, then use this to transfer the pollen. I can even pry open yesterday’s closed female flower and slip the bee in. I suspect the closed flower has something to do with maintaining humidity to allow the pollen tubes to grow, so tearing the petals off could hurt the process. cheers K.
@Kerry: That’s great news! I wonder if it’s the age of the plants or something environmental that caused them to produce only female flowers? Possibly time-staggered plantings or growing other squash family plants as well could allow more pollination options.
I”m a first time gardener and today I finally see a Zucchini growing!! Hip Hip Hooray!
BUT now I”m lost, do I have to do something more??? Reading all these posts has me so lost? Help! Doesn’t the appearence of the fruit mean the bees did their job???
I have tons of flowers.. will go look for the boys and for the girls! LOL
Having tons of luck with tomatos, peas, carrots, cukes, weak on lettuce, spinage, — my garlic is growing nicely too.
All containers. Northern AZ, cool nights, warm to hot days.. starting to get HOT. watering once a day, good, some plants 2x a day as they wilt from the sun.
Febe
@Febe: That’s great! It’s pretty simple – just use the male flowers to pollinate your female flowers to ensure the fruit will ‘set’. You can’t really tell if the bees are doing their job or not, unless you see them actually flying in and out of your flowers. Great to hear all your other stuff is doing well too!
Squash – Lots of open female flowers. Closed males? Planted early no frost but much rain. Seem healthy with lots of leaves. Pruned several leaves as seems too much energy spent on growing them. Some small skinny long fruit coming in but not much and not every plant.
Seems Good amount of squash bees. No pesticides yet. Gonna try to do without.
Can the males be peeled open to conduct hand the polination?
@Clint: The males should open up by themselves in time. You could try a sneak peek inside one to see if it has pollen – I’ve found when I’ve opened them early they don’t have any pollen (yellow powder) on them yet.
We have a pretty awesome organic garden going here but we would very much like suggestions on how to store excess zucchini. Any suggestions would be appreciated. Can we blanch and freeze it?
@Connee: I’ve heard of people slicing and dehydrating it for use in soups and stews over winter. You can also make zucchini cakes and freeze them. I’m sure there would be ways to pickle them somewhere in Google, too. If you have a glut, it would be worth blanching and freezing one as a test – that’s the only way to know for sure! It’d be a shame to spend a lot of time processing them only to discover in a few months’ time that they just come out a soggy mess.
@Connee: If you like using zucchini in baking (for instance zucchini bread or zucchini muffins), then the fruit can be grated raw and frozen in usable quantities (for instance 2 cups). I have done this for a couple of decades, works great.
@Jason: Top tip! Thanks!
Thanks Darren and Jason, both very good tips! The only thing we have a glut of so far is HUGE and very prolific cucumbers. Do either of you know if they freeze like the zucchini?
Thanks for the info. Had, still trying to grow zucchini for years, nothing. I will give cross pollinating the zucchinis a try. I do hope that works.
@Karen: Good luck, I hope it works for you. Let me know how you go!
I have a cucumber plant next to my Zucchini plant. The cucumbers growing seem to have a zucchini end next to the sterm and a cucumber on the starting end. It is about 10 inches long and thin. Why??
@Lori: That sounds bizarre! I’ve no idea what’s going on, but I’d love to see photos if you have them.
Darren, I have a few questions, first time garden grower here and all three of my zucchini plants had mold on the leaves, the one plant was really bad, I removed all the moldy leaves the best I could and the best that I could see and sprayed with milk, I sprayed everything and I am buying Fungonil today, my question is, since I found a female FINALLY, will it survive after I polinate the flower because of the mold problem, and how many times do I need to polinate one female and how long does it normally take the female flower to open, weve had horible rainy and chilly weather here in NE Ohio, any help would be greatly appreciated and thanks so much in advance.
@Theresa: Yes, mold can be a problem, especially if you get a long period of wet weather. Removing infected leaves and spraying with milk are the right things to do, so your plants should be OK. The mold shouldn’t affect the fruit if your treatments are successful, it might just slow down their growth rates a little. You only need to pollinate the female flower once. The opening time of the flowers seems to vary with the weather – faster in warm weather, and slower in cold weather. Good luck!
I have a zucchini plant next to the house on the east side. The plant looks good, but I have not had any zucchini set on. After reading about the male and female flowers, I checked mine. I only have male flowers. Can you tell me why this might be. Thank you.
@Bonnie: I have read that temperature, rainfall, soil pH, nutrient levels, light levels, plant age, watering frequency and other factors can cause more flowers of one gender or the other. As far as what you can do about it – I haven’t a clue! Keep persevering, and hopefully you’ll start to get some female flowers forming. Meanwhile, don’t forget you can eat the male flowers!
Thanks for all the info about hand pollinating, never had a problem before, but haven’t had many bees around this year. I will try it in the morning for my summer squash, which is producing, but very slowly. In CT we’ve had huge amounts of rain and humid weather. My zucchini is the big problem. They don’t have any flowers at all. I have 6 plants, only one has something on it that might turn out to be a male flower, I’ll keep an eye on it. Any idea why no flowers at all. Some of the plants look about the right size for this time of year and some are so tiny still. Planted last week of may.
Hi folks, I planted a garden for the first time and have zucchini growing like bushes in just a month in Oregon. What can you tell me about trimming leaves? Do they affect production?
@Louise: It sounds like maybe the wet weather has something to do with it. Keep persevering, and keep an eye on fungus problems, and hopefully you’ll get some sunshine and flowers!
@William: I sometimes trim the leaves, starting with the ones near the base of the stalk. They tend to dry out and die anyway, and I like to keep them a bit more tidy. All the fruit comes from the growing end anyway.
To Produce more female flowers in a plant you can nip the tip of most of the males to trick the plant. but remember to leave one or two. The best way to hand pollinate is from one plant to another plant using the method that was said in previous posts. if that doesnt work you have blossom end rot, little or no calcium in the soil, the cure dry milk and egg shells
@Anthony: Thanks for the tip – hopefully that answers the questions of the people above with no female flowers.
Dear Sir,
Let me know the following information’s answer.
I work at a research based seed company at Bangladesh. I do hand pollination with pollen of desired male parent and that flower is bagged with wax coated bag but after one hour of that activity some how the bag is open and a bee is entered in to the bag and I think the bee bears unexpected pollen from another flower. What does occur when the unexpected pollen fallen on the stigma ? Can the stigma allow that pollen for fertilization ? Please inform me. and give paper and reference if any.
Thanks
Mohammad Muhebbullah Ibne Hoque Seed Production Officer Lal Teer Seed Limited Anchor Tower 108 Bir Uttam C.R. Datta Road Dhaka- 1205 Bangladesh
@Mohammad Muhebbullah Ibne Hoque: I have no idea! I’m just a gardener, and with things like zucchini that are eaten immature, it really doesn’t matter where the pollen comes from as long as it’s from a plant in the same family. If it were me, though, and it was really important that the pollination were done with the male parent, I’d dump that one and try again with another flower.
Hi, great post! It’s my first time growing zucchini and this might sound like a dumb question but I have 2 plants and 1 is a bit more developed than the other. Can I pollinate the female flowers with male flowers from the same plant or do I need to wait till the other plant develops?
Thanks
@Liberty: There’s no such thing as a dumb question, as they say! Yes, you can pollinate female flowers using male flowers from the same plant. It’ll work fine.
great! thanks for your help
I really appreciate all the detailed commentary about hand-pollinating zucchini and will try it. But I found these comments when searching for hand-pollination of peppers. I want to start a pepper farm of about 160 varieties. Some are VERY expensive (imported by the seed) and, to produce my own seeds, must be raised under row cover all the time (in order to prevent natural cross-pollination). Has anyone any experience hand-pollinating pepper plants?
@AlOlmstead: Peppers have “perfect” flowers, with both male and female parts in them. They’ll self pollinate without bees, as long as there’s a little wind or shaking of the bush to stir the pollen up. Or you can use a fine paintbrush – just touch it into each flower, being careful not to damage them.
Thanks for this info and the very instructive photos – I have had very little succes with zucchinis the last 2 years and will definitely try the hand-pollination this season.
@Pia: Let me know how you go. I hope it helps!
I only have male flowers every morning to pollinate…..is there some reason for this. I have checked on most mornings for almost one week. Very frustrating! I have tried hand pollinating last year with little success – was hoping for better this year. Thanks for any information you can give.
@Shelly: There’s a little info higher up in the comments about potential causes for having more of one type of flower than the other. I don’t have a definitive answer, though! Good luck.
its always hard for me to pollinate flowers, for i go home 2pm weekdays..so when a flower blooms on a weekday ( which is like 70% of the time), i have to rely on my lazy brother to do it for me. i have lost countless bitter melon flowers, aubergine flowers but i dont really mind because i understand that a potted vegetable can only support few fruits.
But these courgettes are really the most difficult to pollinate. for one, they never really bloomed ( thats my biggest issue) and maybe they do but not on a weekend when i can hand pollinate them.
but what a pleasant surprise! today ( weekend) , amongst countless male flowers and dozen of female flowers ( of various sizes) were a medium sized female flower with an open flower, and 2 male flowers ( not yet open but are already ripe). i was so delighted i immediately transferred the huge pot inside our house to protect it from our harsh weather ( windy, rainy then sunny). it was drizzling so i made sure that the inside of the female flower was dry using a cotton bud, and then i carefully opened a male flower ( one of the 2) and hand pollinated the female. i resserved the other male flower for tomorrow ( if another female will bloom) and just in case the male flowers arent that ready yet at least i have another male flower left).
Im excited ..i will post the pics sooon..
PS>…
my 2 zucchini varieties ( the one from England, all green is the one that is very very huge and is having tooo much flowers….right now im thinking if I need to remove some of the female flowers to give more energy on the remaining ones….i also noticed that some of the female flowers get to grow to a good size even if they arent pollinated yet..is it ok to consume them if in case they really dont bloom open? the lenght is about 5.5 inches and i heard that courgettes are better when smaller, so im thinking maybe i dont need all of them to be pollinated before i consume them..is that ok?
im just hoping to at least get a decent sized courgette and then another one to save for seeds.
thank you, gevalia
@lawrence: It sounds like you’re on the right track now. Good luck!
Hello there, two questions. I have two zucchini plants that are growing large and are producing both male and female flowers. One male flower has opened, but for the most part all other flowers have remained closed. 1) Do I have to wait until all flowers open by themselves, or can I take, say, a male flower (like this open one, or one of the other males that looks almost open and most likely have pollen), and open a female flower myself to do the pollination? Or is it bad practice to do anything other than wait until both males and females have opened on their own?
Other question, unrelated to flowers: 2) The zucchini leaves have what I believe is powdery mildew. They’ve had it since they were transplanted into the ground, basically, about a month ago. I’ve been spraying with water & milk for at least 3 weeks, and the plant is growing and going, but the mildew has not abated at all. Should I make my mixture stronger? Change tactics to baking soda or something? Keep going with the milk? Thanks!
[...] that bees or other insects won’t get the pollination work done, you can hand pollinate. This site has some great tips on hand pollination. Just look at yourself as a little artificial [...]
Thanks so much for your post and photos. Very helpful.
I have about 8 zucchini plants that have been flourishing with big flowers each morning, then they shrivel up and fall off. Have seen a few bees.
After reading about hand pollinating, I went to check the flowers this morning and all of them look male. Is that possible? The same thing happened last year and no zucchini. Are there certain male and female plants? I was under the impression that both were on the same plant?
We have had a lot of rain for two weeks and so I just cut off a lot of rotten leaves. It seems that the plants are bigger but gradually less flowers. What do you think is going on and is there anything I can do? Can’t pollinate without female flowers. Do I need different plants?
Help. Novice gardener here. Thank you, Dale
Have straweberry plants that were beautiful and began producing well. Now the beginning strawberries are drying up. What is going on? Thanks, Dale
@lizanne: I usually wait until the flowers open by themselves, but I have opened a male flower “early” before when I had a few female flowers that were ready. I have also opened a female flower early before to pollinate it. In both cases, pollination worked. It sounds like you have a lot of flowers, so why not just try it with a few?
I’m not sure about the powdery mildew. It sounds like you’re doing the right thing treating with water and milk. Make sure you don’t water the plants in the afternoon/evening as well, so they don’t have wet leaves overnight.
@Dale Foster: Glad to help! It is possible to get all male flowers – I don’t know what factors determine which type of flowers will get produced, but there are lots of suggestions in the comments above. I’ve generally found that I get lots of males early on, and then the females start appearing a bit later (along with more males). Yes, you do get males and females on the same plant – there’s no “male plant” and “female plant”. If all else fails, you can stuff the male flowers with ricotta, batter and fry them.
@Dale Foster: With the strawberries, it sounds like maybe they aren’t getting pollinated if the tiny fruit are just drying up and dying.
Hello Darren,
I am sad. the female flower didnt develop into a fruit, just like the others it wrinkled and died.
today 2 male flowers opened, but no female. i have a question, why is it that not all of my flowers open? i mean in a dozen of female and male flowers, so far only 1 female opened ( but died) and only 2 males opened. i guess i failed because they dont open at the same time so no chance of pollinating them succesfully. pls help
@Lawrence: Sorry, I’ve got no idea why that might be happening. It could be to do with water (too much or too little), nutrients, sunlight, pests, disease – so many factors can affect why a plant will not set fruit or even open its flowers. Look after it well and make sure your plant is healthy, and hopefully in time you’ll get some fruit from it.
Thanx for the very informative article! I’m growing courgettes for t first time and I have had lots of flowers. The trouble is the flowers look fine in the morning but by the afternoon they have closed up and began to shrivel. How long are the flowers supposed to last?
@Gareth: That’s fine. Mine tend to open in the morning and then close and shrivel towards the afternoon. As long as they get pollinated in the morning, they’ll be fine.
If you don’t mind a Yank chipping in I find that failure of honey bee pollination on zuchini usually occurs during cooler weather. Try to cultivate mason bees in your garden. They fly in cool cloudy weather when honey bees stay home.
@Billy: That’s interesting. I’m not sure if cool weather is much of a problem in most areas of Australia, at least in the height of the season, but it certainly could explain why the early flowers might not set when the weather hasn’t warmed up yet. I don’t believe we have mason bees here, either (somebody correct me if I’m wrong!). Your info is good for the US/Canada and British readers, though!
According to what I can find on the web they are quite numerous in Australia. You have at least six species that I can find but they are shy little fellows and not easily recognized if you are not familiar with them. They are about half the size of a commercial honey bee and usually rather dull in color. They are easily mistaken for a large fly. Commercial honey bees don’t like to fly on cloudy days because they navigate back to the hive by the sun but mason bees are solitary so they have no hive. No doubt you already have at least some of them in your garden already once you learn to recognize them. By putting up bee blocks for them to nest in you can encourage more to move in. They are unsung heroes doing a lot of good without our knowing it.
@Billy: Thanks for the additional info. I’ve not seen nor heard of mason bees around here, but I’ll ask some people who know about these things. Likely I’ve just not recognised them!
Hi Darren, I am writing you now from Windosor Canada.I sown 6 seeds of Zuccni aprox 5 weeks back.All of them have come up very nicely as a healthy plants.since last 10 days these plants have started flowering. unfortunatly all flowers are male. Every day 5 to 6 new male flower blooms up and dies by evening. so far no female flower has appeared. Bees are moving around the male flowers.
As per you when we can expect to have couple of female flowers and fruits. All plants are very healthy and has big leaves.
These plants are only 5 weeks old. What will be the over all life of these plants? the winter will set in another 8 weeks. I hope I will be able to get couple of Zuccni’s by then.
Regards,
Raj
@Raj: Sounds great! Be patient, and I’m sure you’ll get female flowers shortly. If you get frosts, your plants will die in the first one I think. We don’t get frosts here, and I’ve had zucchini plants live for more than 6 months.
Thanks Darren, Female flowers have appeared. Raj
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