Do they open for multiple mornings?

How long do we have to pollinate before the female flowers wither and die?

Mine stay for about a few days then die.

What time do the flowers open in the morning?

They aren't on a clock. There are variables like variety, air temps and light exposure. But basically it is very early in the AM, shortly after sunrise. They remain open and receptive to pollination for approx. 4-5 hours (again depending on temps, humidity, etc.) and then begin to close. Once closed they may remain on the vine for a couple of days but they don't open again.

Dave

Why not open the unopened male flower and pollinate? You're not going to lose anything.

I've been told that pollen isn't ready until the flower is ready to open. Why would a flower open if it didn't have useful pollen? So prying open a male flower that hasn't opened yet might not do the trick. If you succeed, please let us know.

I tend to think it (pollen maturation) as a probability thing. Maybe the majority of pollen is not mature yet before flower opens, but not 100% in my mind. Even 1% matured pollen should be more than enough. So I would try it. Nothing to lose.

But personally, I won't bother doing hand pollination. Last year my zucchini had female flowers well before any male flowers and they were still pollinated, by bees that I think carried pollens from neighboring plots.

my male flowers have been there for very long but still haven't opened.

Mine stay for about 3 days.

MY PLANTS DIED. PERHAPS TOO OLD. IT'S BEEN A FEW MONTHS.

There are several diseases that can cause these plants to die early. I would also research for SVB and bacterial wilt.

I have cukes in the greenhouse; I hand-pollinate the easy-to-reach flowers, and ANTS pollinate a lot in the hard-to-get to areas.

Yes, I see that too. Ants are really helpful in doing pollination. Which is why plants under row covers can manage to get pollinated.