Ironweed prefers consistent moisture, so you may need to water it more often. This is a tough and hardy plant, so wherever you decide to put the plant you dug up should be OK, and you may also see a new plant emerge from the roots that you left in the ground in the original location. I have Western ironweed that comes up in several locations in my cottage garden, how it got there in the first place, I'm not sure. But no matter how much I dig, chop or trim it, it keeps coming back. It does look pretty though, so I don't hate it too much. Cheryl

I've had good luck germinating V. baldwini and V. novaborasensis here in Z4. They come up nicely and have great blooms. I can send you some seeds this fall if you like.

Ironweed is very slow to start growing in the spring. Once it gets above the soil, it shoots right up. I would try some seeds or other plants to see how they do. Maybe your one plant is stunted for some reason. Was it getting crowded out by other plants?