When To Stain:
There are many different opinions on this subject some say wait a year other say like wait 3 weeks. There is no rule to this. If you live in a dry climate then you do not have to wait long. If it hasn’t rained after you built your deck then stain it.
Most quality deck stains have been ormulated for application soon after a deck is built. Dryness is important, especially when preparing to stain your wooden, outdoor haven. To test lumber for dryness is try putting the edge of the wood into a black garbage bag and leave it in the sun for an hour or two. Then open the bag if there is any condensation on the wood, it’s not dry enough. Another way of telling if you wood is ready for staining is to put a drop of water on a deck and it soaks up quickly into the wood then you are okay to start staining. Or you can use a moisture meter. A wood moisture meter that will tell you how much moisture is in the wood. 19% or less of moisture content is okay for staining.
Cleaning dirt, grime and graying that the sun’s UV rays have caused will help stain adhere to wood fibers and, depending on the wood and stain you choose, allow the grain to shine through. This may require some pressure washing, or even some scrubbing, before staining.
A stain that penetrates wood rather than coating it will protect against flaking and better waterproof. This may mean using an oil-based stain, rather than latex.
Once it starts flaking, you’re in trouble, as that comes from moisture — you have to keep it sealed, if there is any condensation on the wood, it’s not dry enough — it’s got to be clean and dry to stain it.
If you already stained your deck a year or two ago, but it needs a refresher coat, stick to the same type as you first treated it with.
Applying two different stains is a problem, for example, an oil and a latex product.
Making sure mill glaze is cleaned off before staining is important, too, because it prevents the wood from absorbing anything.
You can find more information here at http://decks.hemmingsjones.com