It’s up to you. As a naturally durable and sustainable material, bamboo ages well but is also replaceable without as much impact on the environment. Obviously, you don’t want to keep buying new sets of chimes, but there will always be some wear with bamboo. If you don’t like that look or don’t want to keep replacing them, you can apply wood oil or varnish once a year. For general maintenance, wipe the tubes down with a wet cloth every few months; any object that is hanging and outside will pick up stains and debris.