The choice depends on whether you can/want to live with it for a couple years. But even if you wait, you'll need to sand the old stain off (there will be residual spots)before applying the new.

Powerwashing won't remove the stain. You need to sand it.

Thank you so much for your reply. That's pretty much the conclusion I came to also. I was just hoping there was another option that people with experience staining or sealing decks might offer.

Given that it is this late in the season and sanding the deck would be required whether I wait a few years or now, I'm leaning towards just living with my mistake for a while. Clearly I learned to test the color before it is applied to the entire deck and this will be filed with all my other "make sure you ....." that I've learned in the process of remodeling.

Thank you again for your reply.

Karen

May I ask which color you chose? (We just stained our PT pine deck with Olympic Maximum semi-transparent penetrating stain in Cedar Naturaltone.)

Also, how many coats were applied, and how was it applied? A second coat adds a nice depth of color - it looks dramatically different than just one coat. I assume two coats were applied for durability, though. Brushing on carefully can eliminate any streakiness caused by application.

We used the same stain a year ago for two other PT pine porches. The stain has held up but I find the the color has "mellowed" just a bit. It's hard to explain - it's not exactly faded, not exactly weathered... it just looks a little different, and my husband prefers it now.

If you do choose a solid, (obviously) test it first. We thought we wanted solid, but didn't like how it looked. We decided that if we were to go with a "natural" wood tone, it made sense to allow for the natural variations in the wood to show through. Personally, I don't like solid stains in a wood tone. We have several neighbors who all seem to have used the same solid stain, and it looks tacky.