A section of our privet hedge - probably a few decades old - has died. I can't tell if it just the one plant or if it is going to spread. The hedge is 9 foot tall and so I'm at a bit of a loss as to how deal with it. Do I cut out the dead plants and replant there and just deal with an ugly dip smack on the corner for the next 10 years? Can I cut back the rest of the hedge to split the difference? Any advice?
Dig out as many of the roots of the dead plant(s) as you can. Dig in lots of compost. Replant with new plant(s). Cut the rest of the hedge hard back on the top and one side, cutting the other side the following year.