I've done a rapid soil test and found that my soil's pH is sitting at 7.0, but it's seriously low on NPK nutrients. I'm working on planting a perennial shade garden with hostas and heucheras, and here's my plan: I'll aerate the soil down to 4 to 6 inches using a tiller, then mix in Black Kow cow manure, Hollytone, and biochar. After that, I'll add a soil acidifier on the top inch. When I'm planting, I plan to mix in worm castings and then apply Miracle-Gro Quick Start, followed by mulching with pine bark. But I'm starting to wonder if this might be too much—what do you all think?
2 Answers
Honestly, I doubt hostas will mind much about your soil prep. Since it’s a shade garden, you probably have roots from whatever's overhead. So tilling could cause more problems than it's worth. I’d suggest just planting, mulching, and seeing how they do. Heavy amendments can wait until you see signs that the plants need more help. Plus, soil acidity is tough to shift and usually not worth stressing over unless you're growing something very picky like blueberries.
Black Kow does add some organic matter, but don’t expect a ton of nutrients from it, as it’s more about processed wood and sand. If you’re looking to boost NPK levels, consider adding a balanced fertilizer like 10-10-10 for better results. Adding peat moss might also be beneficial to improve your soil.
Wow, that’s a letdown about Black Kow! I thought it was a solid choice. I trust my rapid test results for now though.

I feel like hostas are pretty resilient. We’ve lost a few plants too, so I totally get the struggle. At least there’s no giant tree sucking up nutrients in your spot!