Legal Question in Construction Law in California

Their hours would be governed by city ordinances, which will vary from city to city. Most of these are probably written to govern "construction noise" and should govern landscaping work as a type of construction, but the landscaper might argue otherwise. If anyone is working before dawn or after sunset, I'd question what they are really doing. If it is tree trimming being done by city workers, forget it, they are exempt.

It looks like you are in LA. If I recall correctly, the LA municipal oridnances have different time restrictions on noise in different areas. Your best bet is to just call the city and ask about your area.