In LA you might get a small second crop in fall via pruning. But even in my greenhouse with 300 day season I haven't figured out how to do that. Maybe if I delayed pruning from June after harvest until maybe August I could push more off season fruit.

The only advantage of a single trunk would be for appearence sake not yield or ease of renewal pruning. Both easier with multiple trunks.

Great, thanks, makes sense about the multiple trunks.

Regarding the second crop, why would pruning later work? And are you talking about basic pruning, like just the tips, rather than a full winter prune?

Where I've forced some early second crop it's been by pruning back to buds that would have been fully fruit buds if allowed to mature. But by pruning before fully developed they were part vegetative and part fruit, a strange concept. You'll recognize these shoots as long clusters of huge berries with no leaves. Perhaps there are other possibilities but that's what I've seen.

You can't force a second crop via pruning unless you wait until fruit buds have at least partially formed. I usually do a full renewal pruning in June right after harvest. This doesn't force fruiting because flower buds haven't had time to form.

So this won't be a full winter pruning more like just the tips. But it's not on the tips where the vigorous fruiting shoots occur. I'd recommend trying different techniques. The right technique probably varies with variety. I've heard Sharpeblue can bear off season in your climate.

There are growers, I think, south of LA that do this commercially. Perhaps you could find info on their cultural techniques and varieties.

Interesting, thanks. I did a search for "evergreen" blueberry production and it seems mexico, FL and Hawaii have some growers doing exactly what you're saying. Sharpblue and Biloxi are the most popular varieties. It seems the second crop ripens in january, though sharpblue seems to flower pretty much year around. I'm still not quite sure how they prune, worth more research. Here's a study about Hawaii:

http://naldc.nal.usda.gov/download/55115/PDF

And here's Mexico: http://www.hydroponics.com.au/issue-105-greenhouse-berry-fruit-in-mexico/