Arum Lillys

Gee, I don't know but I would guess three years.
Remember, that they need to go dormant in late summer.

They grow like weeds in the Pacific Northwest and if anything I end up dumping most of the seedlings.Before I hear an orchestra of protests. I am paid to manage this garden. I do not have the luxury of molly-coddling or sympathy in the triage situation I am in.

I am paid to maintain and control. Arum, and so many other plants in this garden are killing the Trillium and other wildflowers I so more cherish.

So would the former owner.

Tough love, does apply to the garden.

YUP - my computer is dying! Too many glitches to count.
Argh.

You have done what you need to do so far.
Wait for nature to produce what you want.
You may have smaller flowers or different colours.
Wait and see.