The weeds did not grow anywhere near as much in my two weeks' absence as I had feared. It took only an hour or so for me to remove all the foxtails (none of which had developed seedheads yet). I also removed a few broad-leafed plants that I'm fairly certain were thistles of some sort, rather than anything I planted. I then spread some more mulch (coarser mulch than in the past, because I took zdamiana's recommendation) and transplanted my potted rosemary, oregano, lavender, and delphinium seedlings into the ground. Well, at least the ones I brought with me - there are still a couple of pots at home on my balcony with tinier seeds that there didn't seem to be much point in trying to transplant just yet.
The neighbors are at this very moment flooding half the yard again, which might even be what killed the blue flax - it's used to a little more water than it would get from rainfall around here, but it's not used to nearly the amount of the neighbors' flooding. I'm still very pleased that I had the foresight to plant water-loving plants in the most flood-prone portions of the yard, though; if not for that, I'd have lost even more plants. The currant and grapevine I planted are thriving in the puddles.
In the drier portion of the yard, the monkeyflower and California fuchsia are struggling, but after I piled rocks around the fuchsia two weekends ago to try to keep the weeds away from it, the fuchsia has grown a new flower and is looking healthier than it had been. I think it will make a full recovery. I'm not sure what's going on with the monkeyflower, because it isn't being attacked by any weeds. It has a lot of brown patches, while other parts of it are still green. I'm not sure whether it wants more shade, or whether it just got accidentally splashed with herbicide on the brown patches. It hasn't gotten any worse than it was three weeks ago, though, so I don't think it's going to die.
The coffeeberry is looking exactly the same as it did when I planted it in early August, and the Douglas iris is looking almost exactly the same as it did when I planted it last spring. The Douglas iris isn't very well adapted to growing in the Central Valley, so I'm pleasantly surprised that it's still alive at all. I think I should try transplanting it to a wetter and/or shadier area though; then it might actually grow bigger and flower.
Best of all, my redbud tree has three trunks and is now slightly above knee height. It's getting big enough that I think it will give us a gorgeous purple flower show next spring.