The first ingredient in the Kellogg mix is peat. You just made your own mix. If your soil pH isn't acidic I would add sulfur to the bed because it will slowly break down and help counter the rise of pH. Best thing you could do for them would be using only rainwater for irrigation.

http://smallfruits.wsu.edu/blueberry/

http://whatcom.wsu.edu/ag/documents/smallfruit/em8857-e.pdf

Looks like you are really going to have to watch and likely lower PH. 50:50 Peat/Pine bark and native soil is usually fine with a top mulch of more pine bark.

FWIW, blueberries grow perfectly well in the Seattle area in ordinary garden soil - it is sufficiently acidic in this area. It is my firm belief that the need for excessively acidic soil pH is grossly overstated for blueberries as Puget Sound area soils are only slightly to moderately acidic (6-3-5.5) and there are many, many commercial blueberry farms in this area that grow tons of blueberries in unamended soil, as well as countless home gardeners who just dig a hole and plant :-) Blueberries are very productive in this area without the need for a lot of foo-foo soil fussing!!

If you need to amend or acidify imported soil for a raised bed, you can just incorporate a quantity of peat moss to the mix (as recommended by Fall Creek, the largest wholesale grower of blueberries) or the Kellogg products are available at a pretty wide range of independent garden centers. I use their Master Nursery label acid planting mix for all my containerized trees and broadleaved evergreen shrubs and hydrangeas and it is available at my local retail nursery. I used to be able to get their Gardner & Bloome label acid mix when I lived in Seattle at both Swanson's and Sky's.