Yep. Even with a heavy layer of straw mulch and regular watering our broccoli is starting to bolt. I have never yet grown a nice full head on these, but I keep trying.
The lettuce that came up is so-so, but I think that's only because I give it late day shade. We go straight from winter temps to midsummer temps -overnight and back again, repeat, repeat...how any of us (plants included) can stand it, I just don't know.
If you'd like some of the radish seeds I'm growing, just shoot me a mail. I'm pretty sure I haven't given away all I collected yet.