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sewingalot 08-13-2012 05:41 PM

How to make DIY root fertilizer tablets with clay
I found some great articles along the search for diy fertilizers such as this one and that one. But didn't find one entirely to suit my needs. One main thing I kept hearing is you can't add phosphates with iron. They will precipitate, etc. Some of the well known brands such as Flourish Tabs don't have Nitrates and Phosphates added. So I was spending roughly $49 - $1.00 a tablet and they are incomplete as far as nutrients.

Looking around, I found Osmocote and Jobe sticks are great alternatives. They both work great, but aren't customizable. What they give you in the fertilizer is what you get. So if I wanted less phosphates and more potassium, I'm out of luck. So I decided to try the clay route which is a bonus of extra minerals such as a boat load of iron.

Now this gets messy, like incredibly messy if you are doing it right. But it is fun as well if you pretend you are a kid making mud pies.

I sat down and started thinking about what I wanted to include and came up with a list of ingredients based on the two linked articles, guessing, preference and adjusted as I went along on observing the growth. Now mind you, you'll want to experiment around, find out your own blend. Don't be afraid to add or subtract.

This is my personal recipe:

1 cup micros
I start out with a hunk of clay about the size of a 3" square block and add as needed. (Amaco brand is the one I use. Whatever brand, it must be natural clay, not polymeyer)
4 tablespoons KN03
3 tablespoons MgsO4
3 teaspoons K2SO4
2 tablespoons of KH2PO4
1 tablespoon CASO4
Water to help mix

Rolling pin or pasta making machine (or patience if you do this by hand)
Wax paper or other surface to roll out and store the tablets as they dry
Butter knife

Supplies gathered:

Cutting up to manageable chunks:

Rolling out sheets of clay:

Adding in fertilizers (I do this for each fertilizer, I don't combine them in the end just because it's much easier for me to work with):

You start to fold it up to blend it in a piece of clay:

Some will fall out:

This is where it gets a little messy. You dip your fingers or pour a little bit of water on some clay and start working it into the piece, adding more clay as necessary until it is all blended and the clay isn't so wet it is sticking to your fingers. You want it pliable again. It will be crunchy textured if you do it in this manner:

If you did it right, you'll end up with this:

Roll out into long tubes, to what ever diameter you want them. I think if you make them much larger than 1/2 you'll not like them as they aren't very handy or easy to push into the substrate. I like to make them around the same size as an ordinary commercial root tab, maybe twice that size if I'm lazy.

Cut at intervals that you desire, I was about 1/4" but I wasn't scientific, just eyeballed it.

You can roll them into balls and I used to do so. Then I found out this is a lot of work and leaving them flat makes them easier to put into the substrate (especially with tweezers). They don't have to be pretty, but functional.

Sit them aside and let dry (away from kids, pets and adults that may want to eat them.) They will turn a lighter color as they dry. I like to flip them over the next day. Takes anywhere from 1 day to a week to fully dry. If you live in a dry climate, they will dry faster. Here, it takes around 3 days. You want to have them throughly dry before putting them in baggies as clay will mold if moist. In fact you can see this in stored clay often times, it's harmless unless you are allergic, though. Stores indefinitely in a cool dry place.

Depending on the size of the cuts, I'll get around 300 - 400 pieces with one batch. You will have more or less depending on how much you make, how big you make them. And the amount of fertilizers in each will vary slightly depending on the same factors and how well you mixed them. They'll last you for a super long time, you can give away some to friends or fellow hobbyist, sell some, etc. And it cost next to nothing for each tablet.

Tips I found along the way:

1. If you have hangnails, a paper cut on your hand or any other open aware, be forewarned. The nitrates (and some of the other chemicals) will burn like crazy. I panicked the first time thought I was getting a chemical burn. Turns out I had a paper cut, lol. Best to wait, tough it out or wear gloves. I don't like the use gloves as it doesn't let you feel the clay texture.

2. You can emulsify the clay in a bit of water and then add in the fertilizers. You'll have to add in clay as well until it is no longer liquid and you can once again mold it. This is a little more tricky as you start out with cake batter consistency and have to get back to a clay that is able to be molded into tablets.

3. Another method I've done is roll out the clay, let it harden, smash it up, add the ferts and slowly add in water until it is back to pliable clay texture.

4. It makes a mess. Have a towel handy, and you will want to be near a faucet (or a bowl of water) to rinse you hands off as you go. Also, clay can stain, so don't wear your Sunday best or use a good towel.

mistergreen 08-13-2012 05:55 PM

You can use a wine bottle if you don't want to mess up for rolling pin. Or put wax paper between the clay & rolling pin.

I wonder what happens if you really fire in a kiln. It definitely won't break apart in water but it might seal the ferts too much or will it be like osmocote.

somewhatshocked 08-13-2012 06:07 PM

This is a great post and should be saved by folks for future reference.

I've found that firing them just causes them to hold together far too long when submerged. A year later, I've found them when cleaning out tanks where they're still nearly hard as a rock.

I tend to do this when I don't have any gelcaps for use and I think it works waaaay better. It's always way more fun making little balls, as well.

I've found that it's a good idea to keep a few wet paper towels handy when making things. Usually use them to temporarily store chunks of clay while working with other chunks. That way it's moist when you go to shape things.

Always best to spread out some newspaper or an old sheet in the floor, plop down all your stuff and start a DVR marathon or watch a movie. It's surprising how many little fert balls you can make in a couple hours.

WallaceGrover 08-13-2012 07:17 PM

Oooh, this looks like fun.

I have a big 5 pound brick of amaco clay left over from using it to fortify my dirt substrate. I was told you specifically need the clay to be the red variety, because it has a lot of beneficial traces like iron.

I'm adding this to my bookmarks, and definitely making some soon! Do you have any idea as to how it compares to to other popular root tablets?

sewingalot 08-13-2012 10:55 PM

Good tips, Mistergreen. I thought the husband was going to scream when he saw me using the marble rolling pin. I bought a cheap pasta maker after that. When I tried similar with firing them, they became more brittle as well. I suspect it's an unnecessary step. Somewhat - I never got into the gel caps. Too much fine motor skills required.

Wallace, it's fun in a going back to childhood sort of way. After the first hour, you start wondering why you started. By the end, you swear you'll never do this again. And luckily, you made so many that by the time you need them again you forgot all about the labor involved. ;)

Oh, and there are reasons you may want to choose the gray over the red. For instance, if you use white sand or other substrate, when you go to uproot if the plant has grown into the clay (which it will) you it will be noticeable. If you use the gray, it's not so much.

I think it works much better. Some of the most popular ones don't even have all the macros needed for growth and they are customizable whereas the commercial ones are not. However, the work involved makes the pre-made ones more appealing. It's a trade off.

WallaceGrover 08-14-2012 08:28 PM

I started on my (small) batch today, and so far it's looking good. I did the liquid emulsion strategy with amaco Mexican clay. My clay had been sitting for a while so it was REALLY dry, I pretty much had to do it this way, presoaking until I could make a smooth mixture with a bamboo skewer.

Here with 3 tablespoons of equal parts KNO3, MGSO4, K2SO4, and CSM+B. (Phosphate soon to come) Even with all the ferts it turned out really smooth, like buttercream frosting, the trick is going to be getting it to where it's workable.

So glad you posted this!

somewhatshocked 08-14-2012 08:58 PM

A bonus to clay ball ferts: they sink quickly and you don't have to worry about them floating up like you do with gelcaps.

sewingalot 08-14-2012 09:31 PM

You can add more clay to the mixture , ferts or even dirt to thicken it. Or you can pour it into a cake dish as is and let the moisture dry out. You risk it being more brittle or a little mold this way. The mold is harmless though. Before it fully dries, you should score it to make pieces. Best to add more clay if possible. This method is a little more trial and error. Adding clay will make the amount of fertilizer less potent though so keep that in mind.

mistergreen 08-14-2012 10:03 PM

You can get fish molds and stamp on the clay to make them look like goldfish crackers :)

or better yet swedish fish!

ua hua 08-14-2012 10:25 PM

Very informative thread. I have been wanting to make some clay root tabs but don't think I need a huge amount of the clay that they sell. I might have to just buy some to try out though.

WallaceGrover 08-14-2012 10:58 PM


Originally Posted by sewingalot (Post 1978683)
You can add more clay to the mixture , ferts or even dirt to thicken it. Or you can pour it into a cake dish as is and let the moisture dry out. You risk it being more brittle or a little mold this way. The mold is harmless though. Before it fully dries, you should score it to make pieces. Best to add more clay if possible. This method is a little more trial and error. Adding clay will make the amount of fertilizer less potent though so keep that in mind.

I think I'll use a jelly roll pan with wax paper, and with any luck maybe I can catch it when it's in a pliable state :bounce:...

DogFish 08-15-2012 12:01 AM

So being someone that has stuffed a few Gel Caps himself, my 1st thought looking at this is how do you have any control on dosage?

sewingalot 08-15-2012 11:53 AM

LOL, MG. I could totally see myself thinking they were goldfish crackers and eating some before thinking it through.

Uahua, I am going to buy some clay this weekend, if you want to try it out, let me know and I will gladly send you a smaller portion. They do sell it in smaller sizes, but it's more expensive per pound.

Wallace, keep us updated!

DF - this is quite simple. It's a recipe, ultimately. Think of a cake: you put in flour, eggs, sugar, milk, flavoring, etc. Each part of the recipe has a set amount of calories and if you total up your calories and divide it by the number of slices, you'll know how much a piece will be within a small percentage of error. Same thing applies to this method. If you know the starting out numbers, you can do the same thing. In fact, you could make it really technical and weigh each piece as you make them so that you have the same amount in each tablet. However, you can be a less stringent, weigh the entire end product and one tablet. Then just do a little math to find the range. Completely unnecessary in my opinion unless you want to market these with a set amount of chemicals. They work and quite well for the hobbyist. You get the benefit of the added clay and you don't have to spend a lot of money on them. It's all a matter of preference.

Make the gel caps, make the clay, make frozen dirt balls or buy the commercial fertilizers. Makes no difference to me. I'm just putting this up here as I've had many pms over the past year or so asking me how I make them. I figured others including those that aren't currently registered (just lurkers) will also be able to see the process if I created a thread.

Bottom line is I've had more success with this than any other method of fertilization, but this is solely based on my personal experience/needs. Most of my tanks are only fertilized through the substrate, with the exception of the one filled with java ferns. They are getting supplemental water ferts on an occasional basis.

DogFish 08-15-2012 01:21 PM

No offense but unless you put the whole "Cake" into 1 tank, you have no idea what the chemical content dose of each "pc of Cake " is, when you are just sprinkling dry frets on clay.

Even something as controlled as a aspirin tablet can not be broken in 1/2 and insure each pc. is 50% dosage.

I'm not posting to be difficult, just trying to understand how how this method can work with 'Burning' some plants along the way?

somewhatshocked 08-15-2012 02:49 PM

They're root tabs. You're not gunning for a specific dosage, really. You're just trying to get enough ferts to the roots of heavy root feeders.

So I don't think you have to worry so much about dosage.

If you want to get into the nitty gritty, it's easy to monitor your plants over the course of a month or two to see what they need more of. Then add more of that to your next clay batch.

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