Posted: 02/06/2017 at 09:25
I cut my sage hard back in the spring and that keeps it in a nice mound shape ... but cutting it back every spring means that you don't get the flowers as it flowers on the previous year's growth.
To get flowers every year and still keep it trimmed I've found that cutting it back in mid summer after the first flush of flowers works, so that it gets a chance to make some more growth which will flower the following year.
However, doing that means that you do spoil its appearance for a few weeks in the middle of the summer.
I wouldn't call it invasive, but like ordinary culinary sage it will root where branches touch the ground ... keep an eye on that and it's not a problem. However, I let it make a few extra plants each year and then cut them off and pot them up, so I've got a continual supply of replacements.