Stop buying bottled nutes, mix your own for pennies

Been mixing my own base nutrients from raw salts for about three years now and the savings are genuinely absurd. A 25 lb bag of calcium nitrate runs me around $25 and covers multiple full runs. Compare that to a liter of a name-brand cal-mag supplement at $20-30 that'll last you maybe one cycle if you're running heavy feeders. My basic veg formula per gallon of RO water: 0.8g calcium nitrate, 0.4g magnesium sulfate (Epsom), 0.5g monopotassium phosphate, 0.3g potassium nitrate. That hits roughly 150 ppm calcium, 40 ppm magnesium, and a decent N-P-K spread for early growth. Flip ratios in flower by dropping the calcium nitrate a bit and bumping the MKP and potassium sulfate. The startup cost is the only real hurdle. You're buying maybe 6-8 raw salts up front, total probably $80-120 for quantities that will last a long time. After that your per-gallon cost drops to literal cents. I ran the math on my last grow, full veg and flower nutrients for 8 plants came out to under $4 total. One thing worth knowing: you need a decent scale that reads to 0.01g and you need to mix salts into water separately before combining, some combinations precipitate out if you dump them together dry. Calcium nitrate and sulfates especially, always dilute one first. pH and EC meter are non-negotiable too, but you probably already have those.

3 comments

3 Comments

Experienced8d ago

The savings math is real, no argument there. But i've tried the raw salts route and here's where i landed personally: for veg it's great, dialing in calcium and mag is straightforward. Flower is where i got frustrated. Chasing specific terpene expression, i kept second-guessing whether my phosphorus timing was contributing to flavor outcomes the way i wanted or if something was slightly off in my ratios. Hard to isolate variables when you're also tweaking the recipe. Eventually went back to a simpler bottled approach for flower just so i could control fewer things and focus on the stuff that i think actually moves the needle on terps, like temperature swings late in flower, humidity management, and especially the cure. The raw salts saved me money but cost me mental bandwidth i'd rather spend elsewhere. Not saying that's the right call for everyone. If you're running a tight budget or scaling up plant count, the economics alone make this worth learning. Just didn't work for my style of growing.

Experienced8d ago

the mixing-separately tip is the most important thing in this whole post and people still skip it. lost a full res to a calcium sulfate lockout before i figured that out. one thing i'd add from running autos specifically, they move through stages fast enough that you don't always get a clean "veg formula then flip formula" window. i've started mixing a middle ratio that works for the overlap and just keeping it consistent rather than chasing a hard transition. less fiddling, fewer mistakes. the math is genuinely hard to argue with though. my last bag of calcium nitrate has been sitting in a bin for almost a year and i'm maybe halfway through it.

Experienced8d ago

The overlap ratio idea is interesting but i wonder if you're leaving some yield on the table by not pushing harder on P and K once stretch kicks in. I ran a similar "just keep it consistent" approach for a while and my buds were decent but not as dense as when i started actually leaning into a proper late-stage formula. Curious what your middle ratio actually looks like numbers-wise.