Well to be honest, these tactics can work with any sort of hedge that you want to shape up and straighten. The methods are the same no matter on the size of the hedge just the equipment has to change
Levelling off and straightening hedges is a pretty skilled job to get really right so for that reason it’s getting a 5/5 on my skill level.
The tools required do depend on the thickness of the branches you are cutting, for this box hedge I used the following tools but for thicker hedges, saws and even chainsaws maybe required
Brick string line
Solid metal or wooden poles
Very sharp heavy duty shears
A couple of points to add about the tools, it’s first of all very important to have them sharp as possible. also with the shears, they need to have heavy duty blades that are designed to cut thicker wood. I use the Bacho ones and find them excellent for this job. The string line is also important, this string line is designed to be used very taught and is perfect for the Job in hand, other string like twine, garden string may sag with the weight on. Also the colour of the string is important, with this string available in yellow or pink, it shows up very well against the hedge.
Timing is also quite important. I would only do box hedge reduction in mid-late spring up to late summer . There’s a good reason for this and that is the young growth on the box can be very easily frosted. It takes 3-4 weeks for the box to produce new growth, cutting it back from early autumn onwards will mean any new growth produced will be frosted and will allow any frost to enter the plant and cause damage during the winter.