Yes, pressure-treated wood can occasionally turn green due to certain preservatives, such as copper-based chemicals, used during the treatment process. These chemicals react with the wood, creating a greenish tint. The good news? It's temporary, and the color will fade over time. Staining or painting can also help hide any unwanted hues.

Staining pressure-treated wood is a recommended practice. While inherently resilient, it's not impervious to moisture and UV exposure. Staining treated wood is feasible and recommended for enhanced protection and longevity. Applying stain and sealant safeguards against degradation, prolonging its life span. These measures shield the wood from environmental threats while augmenting its aesthetic appeal, ensuring your investment endures the test of time.

Wood stain does go bad, but it will last in the can for between three and six years, provided you use proper storage techniques. Storing wood stain in open containers or in extremely low or high temperatures will cause your wood stain to become unusable much more quickly. Water- and latex-based wood stains typically last for just two to four years, while oil-based wood stains can last for three to six years.

Whether to brush or roll stain on wood depends on the project and your preference. Brushing is ideal for smaller, intricate areas and offers more control over the application, ensuring thorough coverage and penetration into the wood's grain. 

Conversely, rolling is efficient for more extensive, flat surfaces and can save time. However, it is not always the best fit for textured or uneven wood. Some projects may benefit from combining both methods, using a brush for detail work and a roller for broader areas. Ultimately, the choice between brushing and rolling depends on the specific requirements of your staining project.