Do you mow? I can't imagine a plant like milk weed affecting a septic field but assuming they could...mine have crawled past the garden beds and into the lawn and they just get mowed over....

I called my friend who’s president of the Master Gardeners and has a house way out on a mountain with a leach field.

She said yes it will ruin it with deep tap roots and rhizome spread. It is difficult to transplant due to these issues but very early spring or autumn dormancy you can try.

If you simply want to kill off portions of it to limit its spread

1. cut at main stalk near ground and paint the new cut with Brush Killer. its a systemic and only kills what it touches . It doesn’t harm anything nearby or leach into the surrounding soil.

I use it adjacent to my best perennials all the time to kill suckers from a neighbors awful invasive Jujube tree. 😡

I had some volunteers for a couple of years and it bugged me how they went where they weren't invited. It was difficult to get rid of them. I kept pulling up the plants the moment they showed up. But it all started with just one plant. I wish you good luck.

Most people I know refuse gifts of common milkweed because of the weediness. So, sure, you can dig them up, but finding a person to give them to might be harder.

I have had the same experience as Still trailing and murraysmom. it was fine the first year. When it started popping up where i didn‘t want it i knew it had to go. In some areas i believe it has been declared an invasive and should not be sold or used. I did the same as Still trailing and cut it off at the ground and painted straight brush killer. I have also just pulled it up and sprayed the hole with brush killer. I’ll stick to other varieties of milkweed from now on.

Be careful not to inadvertently get any of the sap/milk or sp-touched material in your eye. It is very alkaline and caustic. One year I must have either gotten sap, soil in my eye or rubbed my eye. ENORMOUSLY PAINFUL and I couldn’t get to the ER fast enough. (They were great.)

Common milkweed, like many natives, have evolved to grow in competition with other aggressive plants. They should never be planted in garden beds, but do great in meadow like plantings with other equally aggressive neighbors.

But as gardengal has explained, they cannot be considered invasive.

Thanks for the correction. gardengal

" is native to North America so by definition cannot be considered invasive. "

It is found in other parts of the world where it is invasive, but not here in NAmerica.

What is considered ”good” milkweed for a small suburban yard. I am cutting my flower beds way back and extending the grass, which is the only plant my husband likes. I can no longer keep up with the beds, but would consider milkweed if there is a well behaved variety.

Both the common milkweed and swamp milkweed are multiplying at a fast pace back in the meadow; I didn't expect things to progress this rapidly, but it's welcome. I planted some of the orange butterfly weed back there and it does well but I haven't seen any new self-sown ones crop up anywhere yet.

Swamp milkweed grows terribly in my beds, go figure. It seems to peter out over time, and one year I saw the weevils. But left alone to its own devices with zero supplemental watering, intense blazing all-day sun and intense competition? It thrives. LOL!

Common milkweed pops up by the house where I don't want it. I usually just pull it out, or DH mows over it if it's in the grass. Someone on the board in the past said if you keep pulling it out the "mother" will get the hint and quit sending up runners in that location. I can't say as though I've found that to be true, but I keep pulling anyway. One year I dug some out and transplanted to the meadow, that seemed to be successful but IDK which is which back there (what I transplanted vs what nature planted).

If you're worried about the milkweed encroaching on the septic field, can you put down some of the bamboo barrier stuff to keep it within bounds? Maybe a large ring around the milkweed "bed", down about 12-18". You can get this type of barrier on A*n.

The orange Butterfly weed is very well behaved and gets a lot of monarch caterpillars on it.

"Prolifically bothersome" plant ;) Is that a better designation? I am beginning to think about callirhoe involucrata in that way. I do love me some winecup, but not when it's my entire yard. I also love milkweed. Even though, mine always get aphids. Oy!

"I do love me some winecup..."

Me, too! Although, oddly this year the lone winecups clump I have is a lot smaller than years past. Not sure why. I've never moved it, it was quite full and rambly last year. {shrug}

If one has a small patch in a perennial bed couldnt you just deadhead it before the seed fluff flies?

"If one has a small patch in a perennial bed couldnt you just deadhead it before the seed fluff flies?"

You could, but common milkweed is still going to colonize -- it's rhizomatous.