Last year I started a whole bunch of perennials from seed for a butterfly/hummingbird garden. Agastache foeniculum ("Blue Spike" anise hyssop) was one of them. The plants grew well and bloomed that first year. I wasn't that crazy about the light lavender color so I've been wondering if I want to keep them.
WELL, let me tell you something- I made the mistake of letting these things go to seed and now they're popping up all over the place! They are, by far, the worst offender in my garden. Now I wonder if I'll ever get them all out!
In all of my research I don't remember seeing any mention of how invasive the seedlings can be. There's even an article about them in the June 2003 issue of "Garden Gate" magazine and it doesn't mention their prolific self-seeding. It says to propagate them by division!
I have half a mind to rip out the original plants (which are 4 feet tall this year!) just because I'm afraid I'll miss dead-heading one of the flower stalks before it spreads its seeds to my neighbor's garden.
Well, I just wanted to get that out of my system.
Doug in NJ.