First off, you need to identify the trees. Cedar and spruce are not pine
trees. All 3 consist of many different species that have different cultural
requirements and natural habitats. You dont mention where you are from or what
zone you are in, I suggest you find out if you dont already know. As for
watering, there is no way to set a schedule for this. Since many plants are
adapted to more than one climate, watering requiements will depend on where the
plant is located. The best way to check for watering needs is to physically
check the soil with your hands for moisture. As for the fertilizer, it dosent
matter what kind you use, so long as it has nitrogen, phosphorus, and potassium
in it. It is not feasible to alter the pH of 100+ trees, many of which are of
mature size. Changing pH is a very slow process that takes years to
accomplish. I would suggest having a soil test done before you do anything.
As a last note- fertilizer is not medicine- if the trees are dying,
fertilizer isnt going to help. If your pH is as high as you say it is, the
plants wont be able to take up many of the nutrients provided in the fertilizer
anyway.

Toad