Your hedge trimmer is an important tool if your lawn includes bushes, shrubs, and other landscaping features to tame and maintain. How to Tell When You Need to Sharpen Your Hedge TrimmerMost manufacturers say you should sharpen a hedge trimmer after every 50 hours of use. Step 1: Clean Your Hedge TrimmerBefore you actually get in there and sharpen your hedge trimmer, you should make sure that it's free of any debris or grime. Rotary tool: As with an angle grinder, a rotary tool will save you time as you sharpen tooth after tooth. Step 5: Work Your Way Down The BladeSharpening a hedge trimmer is a repetitive process.