Begin by cleaning down the bluestone pavers. Sweep the loose leaves and debris away, then hose off any mud or decomposed parts. You will then need to put on some waterproof gloves, safety glasses, waterproof boots and protective clothing (such as overalls) to prevent your skin from coming into contact with the chemicals you will be working with.
Next, fill a bucket with 10 parts warm water and 1 part household bleach. Make sure that you mix this solution together thoroughly. If there are any plants nearby to the stained areas of bluestone, cover them with a plastic drop cloth to protect them from damage caused by the solution.
Simply pour the bleach solution onto the affected areas and let it sit on the bluestone surface for about 5 minutes. Then, take a medium bristled brush and scrub at the stone until the stains have been removed or faded. To finish, hose off the bluestone with clean water.
To prevent further stains from forming on your bluestone, you should consider coating it with an appropriate sealer. This will form a protective barrier between your stone and any stains that could potentially seep into it.