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
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