I live in Joshua Tree. There's no flowers here yet, but the low desert is already so green you'd think you're in Ireland or New Zealand and there's also quite a lot of flowers, but it'll be much better in another month or so. Joshua Tree (the town) has no flowers yet and the peak is probably at least a month away and maybe longer for Joshua Tree National Park (higher altitude). I've never seen the area here so green in my 35 years of living here. It should be all time phenomenal for flowers over the coming weeks. I'll have to take time out from my Sierra snow shooting when it really starts to happen.
Other desert areas may already be peaking. For constantly updated wildflower photo info for California, Go Here
I need a few clones. I want to do a full on wildflower thing, but also continue my full on Sierra snow shooting and also do full on Photoshopping of my images and also maybe work on selling something now and then to keep it all going.