Believe it or not, pencil shavings sprinkled around the area will allow them to thrive after a week or so. I tried this with some of mine and though it took a few weeks I had an amazing turn out.

Weird. I wonder why they help. But, I will try it. Thanks!

Butterfly Bush seedlings may be susceptable to fungal disease in their early stages. My thought is the pencil shavings control the moisture content at the top of the soil, where the fungal disease begins it's first stage. I had 6" seedlings that I planted in my first garden. We had a very wet season and they rotted away. The following year I got gallon sized plants that I got to grow.

You are one zone up from me.
Last fall I read that Butterfly plant seeds don't like being pampered.
So when the plants produced seeds I just tossed them on the ground (where I wanted them) like they would do naturally. I have so many young plants now that I thinned many, many.
Saw a monarch on the parent today.
Bottomline, try to toss seeds on the outside soil in the fall.

I'll try that way too. I don't know what I do to the "easy" plants, but it seems like the easier people claim a plant is to care for, the more likely I will have trouble with it.