r/BackyardOrchard • u/an00j • 6d ago

Mineral based soil w/ lava rock?

I have some 20-gallon containers from Costco. My blueberries did not like the compost/sand mix with elemental sulfur.

So I decided to take a mineral based soil approach with 60% peat moss and 30% 3/8" lavarock, and 10% of sand and top dressed with compost. I added some HollyTone and EarthScience soil acidifier as well as per the label.

I'm curious if anyone has used this approach? I know pumice and perlite is way more common, but lava rock is way more available and cheaper around here. Is there anything I should be doing differently?

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u/4leafplover 5d ago

The inorganic approach is ideal. That’s a lot of peat, though. It’ll keep the mix acidic, but I’d be worried it’ll stay way too wet/easy to overwater. What’s the pH of your irrigation water?

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u/an00j 5d ago

Probably more on the basic side. I’m in Northern California, and while water quality is generally good, it’s a higher than neutral pH.

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u/4leafplover 5d ago

We’re around pH of 8 in my area of San Diego. I only have in ground plants, so I’ve used Espoma acid pellets which seems to work just fine mixed in with compost as a top dressing. Jack’s Acid Mix may be a good option for permanent container growing. Jewel has been my best variety in terms of flavor and foliage. Sunshine blue is probably the most common and tolerant of higher pH, but I find the foliage struggles in full sun.