Did you check the stem of plant?
I lost two zukes by Squash Vine Borer.
I did have same problem as you are having.
If it is SVB you see frass and a whole in the stem near the base. Check it out!

I read somewhere that they only open in the AM. Maybe you're missing it?

When are you looking? Summer squash flowers open in the morning. If you're looking in the afternoon you won't see them open. Do you have bees present? I see bees in the afternoon even when the squash blossoms aren't open.

Randy

Thanks everyone. I'm looking first thing in the morning. The male flowers are open, the females are shut tight (and still have that "greenish" tint about them that makes them look like they're not ready to open yet). I've checked for squash borers or anything else -- the plants seem fine.

I have tons of bees in the vicinity, so even if I'm missing them, the bees probably aren't -- the females just aren't opening to get pollinated!

I've been wondering if it is either too hot (every day temps are in the 90s) or they are not getting the right amount of water (although I'm not sure if this is symptomatic of too much or too little).

Please help -- I'd really like to get some zucchini this year!

I peel them open and hand pollinate them anyway if they look mature, and that seems to work. Pluck one of the male flowers, take the polliny stamen, and peel open the female flowers and rub his parts around in there.

Hi,

I also open up the flowers myself...do exactly what greenmulberry says and you too will be overrun by zukes....

And for those who saw my post earlier with the same question about pollination---yes, my children are now sick of zucchini! :o)

Pam

I had to participate in squash hanky panky recently with a spaghetti squash vine recently. I opened the female flower, stuck the male parts inside (thought of a couple dirty jokes about squash) and then let nature take over form there.
I now have one little spaghetti squash growing in the vine :)

Try that with your females not opening!

I am having the same problem, and I have checked while it is still dark out (5 am), first light, mid morning, afternoon, and dusk. Too early, cause flowers are not open, then later shriveled zucchini. I have NEVER had this problem before and it is really irritating me. I will try forcing the flower open and hand pollinating as suggested, but I know this does not always solve the problem. I will report back if it does or does not work.

My female zucchini flowers won't open either. I have checked at all times of day. The zucchini behind the flowers get around 4 inches long but the flowers never open and the zucchini eventually just shrivel up. I hand pollinated a couple of the flowers but the zucchini still shriveled up.

It has been really hot here. Any ideas?

I have the opposite going on. My first two female flowers have opened, while the males are still tiny. On the upside, I think someone nearby in the neighborhood has some zuke plants because those two females seem to have been pollinated.
But what usually happens(for me anyway)is the plant puts out a flush of one sex of flower or the other early on, then the other has to catch up, then finally, there will be both male and female flowers at the same time so pollination can take place(either by hand, or by insect). I usually plant only one, so I have to be patient and wait for both flowers to be present.

I am glad I found this thread. I'm not really sure how I missed it.
I am having the same issue with my squash and zucchini plants. I have gotten one squash so far. There have been several other female flowers that have done as others said and never opened and just shriveled up and died.
I will have to try and pollinate the females by opening up the flowers myself.

I had this problem in my first garden year, see my earlier post. I finally read that this is a common symptom for a plant that is stressed. That first year, my zuch was crowded, shaded, water stressed by drought, and I had tried to train it into a tomato cage to keep it from taking over the space in the square foot garden. I wonder why it was stressed? LOL Now I plant my zuch's in a more sunny location with at least 4 square feet allocated to it and steady drip system irrigation. Haven't had the problem since. So figure out what is stessing your zuchini plant, and you might solve the vestal virgin zuchini problem in your garden.

Now that I think on it, that cage kind of worked like a chastity belt, no wonder there was no zuch sex going on!

Best of luck!
Susan

Hmmm, evidently all I needed to do was post a message about my female zucchini flowers. When I checked them this morning 2 were open. I hand pollinated them just to make sure but I did see a bee out there later on today.

ZUCCHINI MANIA!!!!!!

I checked my base stem very closely and saw a little damage and I saw a tiny bit of damage on a few of the undeveloped tiny "would be" squash. I put some insecticide powder on the lower stem, down at the base area. I also cut back on the watering (in a hay bale). Not sure which one worked (probably the insecticide) but I now have squash again!!!

Naomi i really cant understand myself iam so stressed my zuchinni develops little zuchs and will not open they shrivel up and turn brown i disposed of them and am hoping to find some of my female flowers to open in the morning i give them kelp fertilizer and tum calcium tablets at the base of the plant and water them at least twice a weak they are at least 28 inces apart please can somebody give me any answers

My experience has been that most of us "over care" for our plants. My natural instinct is to give them more water when something isn't quite right but most of the time that isn't the answer. When in doubt, I cut back on the water. Mulching and very little supplemental watering (once plants are established) seem to do the trick at my house anyway.

My squash plants are getting male blooms and they do open. One at a time though. The females blooms aren't getting big enough to open. What can I do?

Each year, if I recall correctly, many of us are frustrated by the coyness of our female Cucurbitaceae.

From what I have gathered, it can be a reaction to stress. Whether climate conditions, water issues, nutrition issues or insect stress (check at the very bottom of your stems (the couple of inches just above the ground). Many time stem borers have attacked your plant and you don't even know it. That is one of the things that happened to mine this year

I am having the exact same problem and was hoping someone would have a solution. The female flowers are so small that they can't open and the fruit turns yellow during this phase. I only get one or two zucchinis per year. So frustrating.

I have the same problem with my zucchinis -- the female flowers come on first with tiny zucchinis attached, but they never open and there are no male flowers. The plants are healthy (planted from seed from a local reputable seed company) and have no powdery mildew or insect damage that I can see. My question: Should I pinch off at least a few of the too many female flowers to lessen that stress on the plant to see if it might help more male flowers catch up? Also, I read somewhere that pinching out some of the outside stems that have no flowers, to sort of force new growth of stems that supposedly will tend to have the opposite gender of flowers. Any truth to this?

open them by hand and use a makeup brush to pollinate

My zucchini are 4 inches with flower closed at all times. Healthy plants other than 95 degree weather. When I force open one to pollinate the inside is still green instead of yellow. The self pollination did not work. I guess the heat is too much stress. If it's not one thing...it's another. Can't get fruit from what is supposed to be the simplest plant to grow

I think it is understood that if pollen isn't viable, possibly because of heat or nutrient stress, the flower won't even bother to open. Also, be careful. The female flowers open for only ONE DAY. The male flowers can stay open for several days.