Hydrangea grows how? Another question

Sister was gifted with a small, potted hydrangea.  Thinking she had nothing to lose, she stuck it in a bed in front of her house and has been trying to figure out whether she should keep it, ever since.  Unknown variety but it looks like it blooms only on old wood, which is iffy in MA.  But it has had some good years.  This year the plant was bigger and beautiful but didn’t bloom.  Providing it with a winter cover of remay has been discussed, if there’s any hope that it might bloom next year.  And as we were looking for signs, we wondered what the side buds were for?  Inquiring minds.

sister's hydrangea
sister's hydrangea