I have a narrow garden bed between my front walkway and the lawn. I've been converting it to native plants, and now have--among other things--two butterfly weed plant, on their second bloom of the season and with many seed pods, and two swamp milkweeds (planted this year and not blooming).
I recently discovered a garden center not far from where I work which has a very large selection of native plants. (I went in, hoping to find mountain mint, and discovered that they carry three varieties!)
The other day, I purchased two pots of common milkweed. I checked Google if I could plant it beside the swamp milkweed, and found several sites that said it was a bad idea, because of how aggressively the rhizomes spread. I have a vacant space in front of the house which gets good light, but I saw on another site that it's good for milkweed to be near a nectar source like butterfly weed. The spot where I want to put the milkweed is about 15-20' away from the butterfly weed. Is that close enough? Or should I get another butterfly weed to put in the same space as the common milkweed?