Will Miracid actually lower soil pH for blueberries
So, first post, I'll give the backstory. On a whim this spring I planted 11 blueberries, 5 Polaris, 5 Chippewa, 1 pink lemonade (yes I know it is going to die, but the 5yo wouldn't be talked out of it.) This was spur of the moment as Lowes got in some beautiful plants from a PNW nursery, in addition to their sad looking usual self sourced crap. We had an area beside the house which needs some attractive ground cover after I cut down 3 large spruce so I figured why not double duty?
Now of course they got these in the last week of April, so I spent a month rolling them in and out daily, hardening them. They were in bark chips, I kept them nicely hydrated and applied Miracid (well actually the new MG Azalea...) weekly to them at that time. Planted them Memorial Day weekend. Dug goodly sized holes and I used essentially a "container mix" consisting of 1/2 peat, 1/4 very small spruce chips, 1/8 topsoil, 1/8 composted layer of spruce needles that was covering the area where I planted. Mixed in 1/8 cup of Lowes Sta-Green Azalea... food per hole.
Planted these along the SW corner of my house which does get sun from 10a-11p in the summer. Soil here 4" of very sandy soil then countless feet of glacial rock, hence my "container mix" into the holes.
So they have done nicely (the "pink lemonade" the best cruelly) enough, but I have this inability to get the soil pH down. I first tested after about a month, got 6.8 on 2 different meters, confirmed by analysis by extension office. Since then I've been mulching in coffee grounds 2/week and putting on the MG Azalea 1/week at the 1 big scoop per 1.5 gallon ratio. After nearly 2 months of that I've merely gotten the soil to 6.6. Should I expect better, I expected better from the start!! What should I do now, I've been tempted before winter here to mulch in another 1/8-1/4 cup of the Sta-Green per plant. I've bought some Epson Salts but haven't tried that route, looked for sulfur but can't find it.
The 5yo did con me into letting a couple berries go this season, left 4 each on the best of both plants, the Polaris are about ripe today, the Chippewa couple weeks behind, hopefully they will have enough season in the future.
Oh, last thought, I water these with my well water, which has a fair amount of iron, and is pretty hard, pH meter stuck in the water shows 7.3 FWIW.
Thoughts, opinions. TIA.