When it comes to trimming back those tall hedges probable the best and safest option would be to use a cordless pole hedge trimmer. Apart from being able to get up to the top of the growth the fact there is no electric cord makes it that much safer. Options are available with different lengths of blades to suit the individual’s needs.
The top part will swivel to 90 degrees which is great for cutting the top of the hedge, 45 and 33 degrees settings can be for creating other angles. The batteries used most often today are Lithium-Ion and come in varying power ratings. Obviously those with larger areas to be maintained might be better of choosing models with the larger voltage batteries.
Some models come complete with batteries and charger, some with battery only and indeed I have included one on my list here that comes complete with another version for general work.
Check out my selection below.
40V Cordless Tall Hedge and Shrub Trimmer
Cordless 20-Volt Lithium-Ion Pole Hedge and Shrub Trimmer
Cordless 3 Position Pivoting Head Pole Hedge Trimmer