Ask-a-Dave's-Gardener: Hydrangea dying where baptisia touched it, 0 by mrzeigler

mrzeigler wrote:
I have a vase filled with cut baptisia. Some of the baptisia extended above a small potted hydrangea that was given as a gift and has yet to be planted outdoors.

The baptisia flowers are mostly spent. It has dropped flower petals all over the table and the hydrangea. What’s odd is that portions of the hydrangea flowers have turned brown and died back. It seems this is consistent with where the baptisia may have touched it, but — since it was my wife to noticed this and she separated them — I can’t say for certain.

Is it possible that the damage is related to the baptisia? If so, what would have triggered this?

More info: the hydrangea was wilted and very dry three days ago. We watered it and it sprang back. Although all of the flowers were wilted then, not all have turned brown since — those that likely had the most contact with the baptisia seem to be the most affected.