Unlike hedge shears, hedge trimmers are primarily electric and often have double-sided reciprocating blades. Since the blades on these types of trimmers are made of a higher quality, hardened steel, they should not require sharpening throughout their lifetime. If your hedge trimmer blades catch on a hard surface such as a stone, glass or wire fence, however, it may put a nick in the blade. In this circumstance, hedge trimmer manufacturers recommend sharpening the blade if the nick appears to affect how the blades function.
Wipe off all dirt and debris from the hedge trimmer blades.
Inspect the blades for damage, especially nicks.
Remove the battery from the hedge trimmer before sharpening its blades.
File any nicks with a fine-toothed file or sharpening stone. Move the file from side to side or back and forth along the nick until it's removed. Move the sharpening stone in a circular motion over the nick until it's removed.
Clean the blades, after sharpening, with a soft cloth dampened in a solution of water and a few drops of a mild liquid soap.
Apply a light film of machine oil after cleaning to prevent the blades from rusting.
Lubricate the blades before each use and after refuelling to maintain them properly. Remove dirt and debris from the blades after each use. Adjust the blades before using so they move freely. The trimmer's manufacturer should provides guidelines on the appropriate gap measurements necessary for proper operation.