I know I’m not the first person to make this mistake, and I won’t be the last, but perhaps you can learn from my own ignorance.
About 4 years ago, these tall plants started popping up in just one part of one of my rose beds. For a year, I ripped it out whenever I came across it. Then I found out it was wild milkweed. I knew just enough to cause myself years of trouble. “Milkweed,” I thought. “Hey, that’s the plant that monarch caterpillars eat as their sole food source.” I had the brilliant idea that I’d let that milkweed grow and do the monarchs a favor.
All went well for 2 years. I did have a lot of monarchs in my yard. One year at the end of the growing season, we brought in a monarch egg on a leaf and watched the entire cycle of egg to butterfly. That was really cool. The kids and I enjoyed that a lot. That seemed to validate my reason for allowing the milkweed to grow. And one year I found a hummingbird enjoying the nectar from the flowers. The flowers are funky in design and the smell quite nice. Finally, bees of all kinds love these plants to the point of delerium. More seemingly good reasons to allow it to grow, right?



Here’s a good reason for not letting it grow: it spreads by rhizomes and is, apparently, unstoppable once it gets established. I will be removing this plant from my gardens for the rest of my life, I think.
There are many kinds of milkweeds. Some, like the “butterfly milkweed” are “good” kinds. That is, they will not overtake the entire garden in two years. They are asclepias and monarch caterpillars will happily eat them. Then there are the “wild” or species milkweeds. These are now, in my book, “bad” milkweeds. In my garden it is asclepias syriaca which is so well established. I have been ruthlessly pulling out each new shoot as it erupts in my garden this year. It doesn’t seem to be killing them off. I make sure I get out and pull those (even if I don’t do anything else) every other day or so. I think this time it was 4 days since I’d pulled some. I don’t want to let them get large enough that they leaf out and begin making food; I want them using up their reserves in their rhizomes so that eventually there will be no reserves and, happily, no more milkweeds sprouting in my gardens.
After those two blissfully ignorant years of enjoying the wild milkweed in my garden, came year 3. This was the year when I realized I was about to lose my garden to the milkweed. The plants grow quite tall, about 6 feet in height. They towered above my rose plants, surrounding, dwarfing, and crowding them. About 1/2 way through the season, I went through and whacked all the milkweed down, thinking I’d keep it from going to seed and from getting so big. Ha! They didn’t even falter. I got busy and by the end of the season, once again that particular bed in the garden was lost to the milkweed. (That milkweed also went to seed, unfortunately).
So, this year I determined that if I didn’t do anything else, I would keep ripping out those spears of milkweed as they pop up. And I have, not that the milkweed have noticed. I suppose it will be interesting in an academic way to see how many years I’ll be pulling those damn things out of the garden beds. And all because I wanted to be nice to the monarchs. Now I’m growing some asclepias cultivar from seed. Someday my monarch friends will once again have buffet in my garden, but it will be something more manageable that won’t dwarf my roses or take over the beds.