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
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.