If left untreated, your furniture will gradually fade to a silver-grey colour. Being a natural product cracks may appear but this is a perfectly normal characteristic and will not affect the structal integrity of your furniture.
If an unweathered appearance is required, treat your furniture with a suitable good quality wood treatment such as Teak Oil, (when using Teak Oil, never apply over accumulated dirt or grime as this will discolour your furniture and may turn it black).
About once a year, or before using a wood treatment, your furniture should be cleaned. To remove everyday dirt and the silver-grey appearance, wash with warm soapy water and stiff scrubbing brush, or careful use of a jet wash. When dry your furnitue should be lightly sanded (always sand with the direction of the grain not across it).
Always follow manufacturers guidelines when using suitable wood treatments on your furniture.
Before re-applying any wood treatment, ensure that the furniture is thoroughly clean and dry and sanded where necessary.
Always lift furniture, do not drag.