John, I hand-pollinate a single variety right now (although mine is very early and finished blooming long ago). But when I had a second bush that was blooming I did the same with it, never worrying about crossing pollen.

I just make it part of my morning rounds and brush lightly over any open blossoms as long as blooming goes on. This works for me but not every cultivar may be as self-fertile, I guess.

I would think that heat and dryness are enemies, but I have no evidence to back that up. Since I have the opposite conditions here, it's just my guess.

The pollen is viable on a daily basis, rather than an hourly basis. If when molesting the flower stamens you get residual pollen on your fingers, that is a good time. Just-opened flowers show yellow pollen, but it will not release. Older flowers, say several days, the stamens fall off when touched, not good. Position yourself where some blooms are backlit by the sun and jostle them--you should be able to see some pollen fly.

Heat (>90 ?)and moisture (mist, rain) will reduce success. You might want to contact the California Rare Fruit Growers to see if anyone is having success in the LA area; it could be that feijoa shrubs in that locale are mostly for landscaping, rather than edible, purposes. A few miles inland in SoCal will make a huge difference for this plant.

I thought California feijoas bloomed in May; perhaps your mild climate would give enough time for fruit to form from an August bloom. Up here in Portland, bloom must happen by 1 July for Nov/Dec ripening before hard freeze.

larry gene, are the feijoa blossoms really old after two days? That might explain some of my lack of success, but with the Nazemeth I caught the blossoms when they were fresh, bright yellow pollen, and still didn't have any luck. It's true that I didn't see much pollen, on my finger or on the paint brush I used, but there was some. Maybe the hot weather (95F days, lots of them this summer) did something to the pollen so by the time I got to it in the late afternoon it wasn't working.

I know one person in the WLA CRFG group, he has many young feijoas (brought a bunch of varieties back from N. Zealand), but he's in Santa Monica and there's probably a 20F+ difference in the summer weather. I'll have to check in with the LA CRFG group, they meet in the San Fernando Valley where the summer weather is a lot closer to mine.

Steve, my equivalent of your morning rounds occurs late afternoon and at night. I wonder if hand pollination could be done after dark, would the pollen be just as viable as in the early morning.

From what I have seen as I brush the blossoms and observe the bloom sequence (still can't quite believe you have trees blooming now!) there is a wide range of blossom states at any given time. Sometimes when I brush I see nothing at all, other times I catch a glimpse of pollen wafting around.

Clearly, you have to do what you can when you can. Seems to me you might catch some blooms with pollen in a mobile state and others that are receptive in the early evening. A blistering day, however, might render the pollen useless.

...several, not two...

I would say the pollen is viable from day two to day 4 or 5 after full opening of a blossom. I just use my fingers and they are covered with pollen, very obvious. So I try to work over the blooms every 2 or 3 days. Typical daytime temps are 65-80 in June here.

After day 4 or 5 the pollen turns brown and the stamens loosen and rain down off the bush.

Since there is a 2 or 3 day window of transferrable pollen per flower, I doubt that time-of-day is important.

Definitely checkout that mini-climate versus feijoa fruiting for your locale. Remember that this plant is originally from the uplands of Paraguay / southern Brazil, and New Zealand is not known for hot weather.

This year the bloom was early (mid-June) and done by 4 July, now I have many fruits that are noticeably enlarging, and of course a percentage that remain tiny and will do nothing.
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Even tomato blooms will be adversely affected by 90+ degree weather, commercial growers likely use special varieties or know other tricks.