It's a clump former, but seed blows around no matter where you plant it. I like the white flowers, but cut them all off completely as soon as the first ones start to fade. It's hard to pull out of even loose soil, so it's best to prevent spread.

I planted it and I regretted it.

The flowers don't matter to me so I am going to cut them off before they fade. Are the roots invasive?

No, it just forms a big, bulbing clump.

Never heard that it was invasive - it might be a Southern CA thing and not happen in zone 9. Mine never popped up anywhere but where they were planted when I lived in zone 9 (dry inland bay area, not moist coastal).

Thank you all very much.