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Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. Hydro

Posted by Timmay_8 6a (My Page) on
Fri, Jul 13, 12 at 21:38

I just started learning about gardening a few months ago. I started with only knowing a little about what are bad weeds, and how to cut grass. That's it! lol Well, I have read at least 400 hours of posts since then. I was trying not to ask any questions because I thought that any question or scenario has already been written about and it's just a matter of more searching. Well, school is getting overwhelming and I'm short on time with all my house projects and stuff.... so...on to my first post.

I finally got all the ingredients for the Al's/Tapla's gritty mix. I have enough 1/16-1/4 sifted pine bark (I spent way too much time sifting bags of pine mulch) and turface to make whatever I can with the 50lbs of Gran-i-grit. I have 50lbs of garden lime (looks powdered), 50lbs of gypsum, a slew of pellet fertilizers, and more. I live in St. Louis, and based on what I read (and not my actual analysis) my alkalinity is around 110-150, and my pH is around 10 to 10.2. Here's some of my sources about the water:
and a few posts I've read from other St. Louis natives.

I went to try to buy Foliage-Pro, but they stopped carrying it and I couldn't find a store (last week, but I now have since found a place) that sold it. They did have a torn bag of Scotts Peter Excel 15-5-15 Cal-Mag, that still had 99% of the product still intact discounted to $33 for the 25lb bag. The store associate said that's what he'd recommend anyways, whether it was discounted or not, because of the value and based on how I was going to use it. Because of time restraints, and getting tired of not being able to find things, I ended buying it and trusting him, without doing prior research (which is rare for me). I got home and did some research and it seems as though it would work out.. I think.

I plan on mixing the 1:1:1 with 1tbs/gallon of Gypsum. I think I should be watering my plants about everyday or two, with 1/8 strength fertilizer every time it's watered.

Is this a good plan? Should I change something? If so, what should I change, add, or omit? Please, I'm always learning and am open to suggestions. Thank you in advance.

On a related side note, I picked up a "Aquamist 1" on craigslist for $25 in good condition. I have most of the materials to get that going, and will get it up within a month. It's an aeroponics setup:

Would the 15-5-15 Cal-Mag fertilizer be suitable for the Aquamist also? I still have a LOT more researching to do before I start up this hydroponics deal.

For both the gritty mix and aeroponics, the plants I am growing are mostly herbs (10 different ones, mainly the most common herbs), a bunch leaf vegetables, a few pepper plants, lemon verbena, roma tomato plant, and a few other vegetables. Sorry about the long post. I will have plenty of indoor lighting, and in time I will put some containers outdoors too.

Follow-Up Postings:

RE: Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. H

Oh, one more thing. In the next few weeks I'll finally put together my materials to build a 150gal rain collection system and so eventually I will be using rain water (if it rains at all!) for my plants.

RE: Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. H

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Jul 13, 12 at 22:01

I read your whole post, and I think your plan is excellent. The only thing I'd change is, I'd eliminate the lime - it's covered in the 5%:2%/Ca:Mg in the 15-5-15.

Though I'm not a hydro/aeroponics maven, I don't see anything nutritionally lacking in the fertilizer, and that it derives almost all of its N from nitrate is a plus. I'm sure the tomatoes and peppers (especially) will like it.

Best luck!


RE: Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. H

The only local source for FP is Worm's Way - and you'll pay dearly for it.

The best local source for most grow media, fertilizers, and a bunch of other stuff is Hummert International up in Earth City. This includes Turface, perlite, peat, Fafard Mixes (get #51 or #52 and you wouldn't have to build your own 5-1-1 - it's more expensive though).

There are 2 good sources of pine fines locally but you have to buy in bulk: Kirkwood Material Supply and St. Louis Compost. At various times you will find one has a better price than the other - same with the delivery fees. Either will work as-is for the 5-1-1.

You can only get Axis locally at OK Hatchery or through a guy at the Botanical Gardens .. but I lost his number, sorry. OK Hatchery is always slightly expensive on most of their stuff but at least they have a wide variety. You can get Gran-i-grit there too - but I've stopped using that except for very small pots (buy the perlite + charcoal from Hummert if you want to substitute).

You will find with our water that if you use soiless mixes with high nitrate fertilizers (like the one you purchased) that you will have some serious micronutrient issues. You want no greater than a 3:1 ratio of nitrate:ammonium and probably more like 2:1 if you want the pH to stabilize in the pot around 5.5-6.5. Note what it says on the link you gave for the label: "Potential Basicity: 131 lbs calcium carbonate equivalent per ton" - all other things being equal if the nitrates are taken up by the plants with that fertilizer you will find the pH creeping up over time. We're already starting with high pH and moderately high alkalinity.

That fertilizer is also lacking S and we don't have enough in our water and we also have very low atmospheric SO2 levels which plants can use in lieu of sulfates - or I do where I am anyway.

If you want to use the Cal-Mag product then you should alternate it with an acid-reaction fertilizer that contains S. 25-5-15 would fit the bill (you can get it at Hummert) but so would a bunch of other options. Or the FP if you want to spring for it (supplement the FP with calcium sulfate if you aren't acidulating with sulfuric acid).

If urea doesn't bother you I think Hummert carries the 24-8-16 Peter's product as well - that will give you the 3-1-2 but with no calcium. You would alternate that with the Cal-Mag.

In my experience even if you do use an acid reaction fertilizer you will find that the pH and alkalinity of our water is such that you will eventually run into micro deficiencies with both mixes. Be looking for signs of Zn, Mn, and Fe deficiency and have a plan to correct them.

For aeroponics I would definitely stick with a 2 or 3 part nutrient formula system. Or make your own fertilizer concentrates from scratch (larger initial investment, huge savings over time). To do aeroponics correctly you're going to need high quality pH and EC meters, and a lot of reading or expensive trial and error...

RE: Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. H

Thanks Al. I wasn't planning on putting lime in it. I only mentioned it because I was just listing a few of the other ingredients that I have available in my house. I remember you had mentioned omitting lime to another fella or two that were also using the 15-5-15 Cal-Mag.

To redshirtcat: wow, that's a lot of information. I am in school working towards my Chemical Engineering degree, and so I get the gist of things your mentioned, but I have a lot of researching to do to fully understand things. I'm not starting the aeroponics for some time, and only until I can do it somewhat right. Thanks for the information about the pH levels, because that's what I was most worried about. As of now, I'm not fully schooled in what problems would arise with starting with a high pH, and using a fertilizer that probably won't help the cause. I'm going to tackle your input on chunk at a time later on this week. I was wondering if you give a simplified suggestion for now, so I could start growing some stuff in the gritty mix? If you were to say, "using the 15-5-15 cal-mag wouldn't be the best, but it would be somewhat doable if you buy ______ to supplement it" and fill in the blank, and how exactly am I supposed to administer the fertilizer. Right now, the only other liquid fertilizer I have is alaska fish oil, or whatever it is.

Btw, I somewhat did a little guesstimate as to how many gallons of water can be made at 1/8 concentration from the 25lb bag, and I think that it makes 16,000 gallons! sheeze. If anyone wants to buy some off of me for cheap plus shipping, let me know. :P

RE: Need suggestions with what I have. Gritty, 15-5-15 Cal-Mag. H

I forgot to mention I also picked up some "course calcium sulphate" because I had wrote it on my list to get. It's late and I haven't slept in about 42 hours, and I can't remember why bought it.

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