why does my butterfly bush have leaves with what looks like mold on them?
Butterfly bushes can be prone to powdery mildew. This article should help
https://www.gardeningknowhow.com/plant-problems/disease/powdery-mildew-homemade-and-organic-remedies.htm
Does the bush need support such as stakes? Mine is starting to spread and seems a little flimsy. Thanks.
Certainly you can stake the plant if it needs support. This plant does tend to get leggy and need pruning.
These links will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-care.htm
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-pruning-how-to-prune-a-butterfly-bush.htm
When is the best time to prune back butterfly bushes and can butterfly weed be potted and if so can they stay in a garden shed over winter? Margaret
Butterfly Weed does not do well in containers do the long tap root.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/overwinter-a-butterfly-bush.htm
https://www.gardeningknowhow.com/ornamental/flowers/milkweed/growing-butterfly-weed.htm
When do you prune a butterfly bush?
These articles will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-pruning-how-to-prune-a-butterfly-bush.htm
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/overwinter-a-butterfly-bush.htm
I am removing a flower garden and putting in grass but leaving the Butterfly shrub. When I lifted the mulch and weed barrier there are roots exposed and running quite a distance. Will it hurt the bush if I cut or damage the roots?
There is a very good chance that pruning the roots could damage or kill the plant.
I would recommend covering the exposed roots with 3 to 4 inches of soil and compost.
How do I take a cutting from a budlia tires
This article will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/propagating-butterfly-bush.htm
Should the butterfly plant be cut back in the fall
There is butterfly weed and butterfly bush. I'll assume you are talking about the butterfly bush, Buddleia. It will die back in winter in northern climes. Cut it back to 6 inches when it is dormant, in early winter to early spring wherever you live since it blooms on new wood,