Supplementing Pro-Mix

10 years ago

I have a wicking bed comprised mostly of Pro-Mix and pine bark fines. I decided to perform a soil test to see what was needed and was a bit surprised by one of the results. Here's the breakdown:

PH: 6.5
N: Depleted
P: Depleted
K: Sufficient

I expected pretty much everything to be depleted since this is a soil-less potting mix, but was surprised to see the potash at sufficient levels.

When I planted, I put a scoop of fertilizer and worm castings in the hole, so the plants are healthy and OK for now, but I expect that to be insufficient for the entire growing season.

I am growing typical garden veggies (tomatoes, cukes, etc). My questions:

1. Why is the potash at sufficient levels?
2. Considering these numbers, what would a decent (organic, preferably) fertilizer regimen look like? How much, applied when, etc?

Thank you in advance for your time.

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Comments (6)

greenman28 NorCal 7b/8a
10 years ago
I'd go with Fish Emulsion probably. 5-1-1 NPK.

Josh
Michael
Original Author
10 years ago
Thanks, but is that all I would need? Seems like that would be good for green growth but not flowering. I am OK with a synthetic at this point. Is there a general purpose granular/other product I can use to make this idiot proof? I read that the Dyna-Gro Foliage Pro is great for house plants, so I'm thinking that something similar with the micros would be helpful.
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greenman28 NorCal 7b/8a
10 years ago
You said you have the potassium covered, so why wouldn't a 5-1-1 fish emulsion work?

Josh
Michael
Original Author
10 years ago
Phosphorus is also deficient, which is only a 1 in the fish emulsion solution. This is a sterile mix, so I am also concerned about micros and even introducing beneficial bacteria.
Nil13 usda:10a sunset:21 LA,CA (Mount Wash.)
10 years ago
How did you test it? Did you send it into a lab?
Michael
Original Author
10 years ago
I used a home test kit. The K was a surprise, as I expected everything to be deficient. I'm not sure if that is typical with a peat-based mix. I would also expect magnesium and calcium and other minors to be deficient.