Blueberries - ph down?
I am planting seven 1-gal blueberries into larger pots (either individual 5-gal pots or planting 2 blueberries per 22" pot), using the 5-1-1 mix with gypsum and epsom salts added, and Miracid for ongoing fertilizer. I have not yet set up my rain barrel, but I hope to use it to water with rain water this summer. Until then, I'll be using tap water, which is measuring at over 8 pH in my four-year-old pond water test kit.
Before I read about simply using white vinegar to lower the pH of my tap water, I went out and bought a bottle of General Hydroponics pH Down, which is Phosphoric acid. I added 1T to a gallon and it lowered my water to about 6 pH on my old pond test kit. I added three more teaspoons, one at a time (for a total of 2 tablespoons/gal), and it finally went to about a 5, which is the lowest this kit tests. I'm having a surprisingly hard time finding another water test kit that's inexpensive and measures down to 4 pH. But I'll keep looking. I suspect that I didn't need to add that much to get the pH down.
Meantime, is it OK to use this Phosphoric acid for my blueberries, or should I stick to vinegar?
Right now my blueberries are in my garage in their 1-gal pots. They arrived a couple weeks ago and have small buds on them, but nothing has leafed out yet. My temps are still around 35-40 highs and 25's for lows for the forseeable future (at least 10 days). I'm not sure if it will harm them to be in the dark garage since they have buds on them, or if it would be more harm to put them out in the freezing nights with those buds on them. Suggestions?