I can verify the ipheion as being amazingly rampant. I confine it to a pot and still need to throw out handfuls every year. I also have a named cultivar (Wisley Blue ?) and it has not gotten out of hand (also in a pot).

Thanksn Iris gal!
it seems like I should avoid ipheion... but that other named cultivars might be ok?

Any more experiences with either?

neither of them is listed on the CA invastive plant list
http://www.cal-ipc.org/ip/management/plant_profiles/index.php

Hyacinthoides hispanica is one of the worst weeds in my garden. I was just digging and pulling more of it today. Yes, it is pretty until it spreads all over and smothers more desirable plants with it's thick foliage.

We didn't plant it. The bulbs were dormant under the sod when we removed the sod and created beds it sprang up in all of them.

I was stupid enough to plant the lily of the valley and muscari that are also extremely invasive here.

If your lawn grass is fairly fine and gets reasonable sun another possible could be Sparaxis for patches of colour, though not blue.

If your summer isn't too brutal then Anemone blanda and Chionodoxa can give that spring splash of blue.

Later on, provided you don't mind deadheading, dwarf Agapanthus can give a good run of blue, too.

I would definitely avoid planting bluebells of any persuasion, Ipheion, and Muscari, if I couldn't get back each year and keep their Garden Thug tendencies under control. Pots and annual thinning seem to work best.