I bought two large perennial mums for my screened in porch several weeks ago.

A lot of the buds turned brown and sort of dried up. The leaves themselves are fine- a few brown leaves at the base that I picked off and a few dead stems. I deadheaded it well today.

I bought the mums in a tight bud state hoping they would last a long time.

They were in bright shade.

I just bought another one and hope to have it last longer.

Did I overwater (probably not) underwater or is it a disease?

How can I make my new one bloom well?