Most Experts oversimplify the stain process.
The Western Red Cedar Association shows a chart in their finishing guide telling you to expect 10 years of durability on properly applied paint—what they don’t mention is that should be expected on a wall of a house. Vertical walls are a little different than a pergola or deck.
I rarely see mention of kiln drying, or back priming, or end cut sealing or pre-finishing.
When wood absorbs water it swells. Swelling causes cracks to appear in the stain or paint and leads to premature failure. The majority of moisture is absorbed from the end grains. Applying stain or paint on a deck after construction is a “maintenance nightmare in the making”.
NEVER use Paint on a Deck or Pergola.
ALWAYS pre-finish the materials all 6 sides with a high quality exterior stain before assembling.
ALWAYS seal the end grains during construction.
Our Guide to Exterior stain walks you through the process of applying stain to decks and pergolas for years of durability. There are many pitfalls, like trying to finish wet wood, mill glaze and applying stain in direct sun which could make your stain fail within weeks. See our Guide to Exterior Stain document below for comprehensive answers.
Our Guide to Exterior Stain Application, http://www.gardenstructure.com/exterior_stain_wood.html
WRCLA Finishing Guide for Cedar