When thinking about plant fertilizer it is of course important to understand what a plant needs in order to survive and thrive. Without getting overly complicated (there are many articles out there there that go in depth into the nutritional needs of various plants) there are three main elements a plant needs: nitrogen, phosphorus, and potassium (you'll often see this referred to by gardeners as: N-P-K). And did you know that you likely throw these things away in your home in abundance? Let's follow one of the three “R's” of recycling (reuse) and put those to use to make a 100% organic slow release plant fertilizer that will likely cost you NOTHING.
* used coffee grinds
* egg shells
* banana peels
* 4 containers (used containers from grocery items work great or mason jars if you prefer them): 3 to store the above items in and 1 for your final mixture that you'll feed to your plants
* Cookie sheet
* Cooling rack (optional)
* A means of dehydration (I'll discuss free options and other alternatives in this tutorial)
* A coffee grinder (either an electric coffee grinder or hand crank coffee grinder)
Now that you have everything, let's get started!
For those who are more visual I've made a quick video:
Step 1: Coffee Grinds
Coffee is full of our first nutrient: nitrogen!
One of my favorite things is when I can find multiple uses for one item. After I brew a pot of coffee in my house I spread those used coffee grinds onto an old cookie sheet and place it in the sun to dry (outside or a sunny window is fine). Used coffee grinds dry quickly in the sun. Mine are usually done within 1 day, maybe 1 1/2 if it's not so sunny.
Once dry you can either store this in a container or you can grind it further in your coffee grinder into even smaller pieces before storing. The advantage of grinding it down to as much of a power substance as possible is that you're creating maximum surface area for you plants to draw the nutrients from.
Step 2: Egg Shells
Egg shells are full of our second nutrient: phosphorus!
I place my used egg shells in a bucket (an old ice cream bucket or anything similarly sized that you have) and place that bucket in the sun to dry just like we did with the used coffee grinds. I have heard of people washing the shells to prevent any bacteria from growing, but I've found that to be unnecessary as long as you're drying them out right away in good sunlight. I suggest you do what feels right to you.
Once dry grind in your coffee grinder as fine as you can and store in a container.
A side note: the egg shells will smell a little unpleasant when you begin to grind them (nothing unbearable) whereas the coffee and banana peels smells wonderful! Just a friendly warning.
Step 3: Banana Peels
Banana peels are full of our final nutrient: potassium!
Simply place your used banana peels onto either a cookie sheet or a cooling rack and place in the sun. I prefer the cooling rack as it maximizes the air flow helping the peels to dehydrate better, but use what you have! If you don't have a cooling rack there's no need to run out and buy one just for this. These will take 1 to 3 days to dry depending on the amount of sun and wind you have.
You'll know they're dry when they're brittle and easily break apart (they'll also turn black). Break them apart and place into your coffee grinder and grind as fine as you can and store in a container.
Step 4: Optional FYI: Alternatives to Sun Dehydration
I live in the northern Mid-West. The sun isn't always efficient enough for outside or even window dehydration. You have two alternatives during these weather conditions: a commercial dehydrator or you can simply use your oven.
To use your oven it's as simple as setting your oven to 120 degrees F. Drying times vary (as much as up to several hours for the banana peels because they start out so moist) so check them often. Remember we want to dry, not cook. Feel free to try this method if sun drying is not an option.
If you have a wood stove simply placing the items within close range of your wood stove would surely do the trick as well!
Step 5: Mixing Your Three Nutrients
Different plants desire a different amount of certain nutrients. However, nearly all will be perfectly happy if you simply combine these in equal parts. (If in doubt, research first!) So grab another container, measure out an equal portion of each of the three items we made: ground coffee beans, egg shells, banana peels, and mix well!
Step 6: Feed Your Plants
This is a slow release plant fertilizer. So in other words as it sits on (or in) the soil it will slowly release into the soil and your plant will feed on these nutrients (unlike a liquid fertilizer which reaches your plant much faster). Having said that if you're re-potting a plant (such as a seedling) mixing a small amount into your potting soil (I would say no more than a couple tablespoons per 1 pound of potting mix) and then simply sprinkling the top soil once every 2 – 4 weeks with more of your mixture should be well more than enough fertilizer for most plants. Keep in mind that over fertilization is just as bad as (if not even worse than) under fertilization. Less is always more, don't over do it!
Save money, energy, and recycle! And last but not least.... happy growing!
Finally, make this a fantastic and fun learning lesson to share with your young children or classroom by visiting: The Homeschool House
Step 7: Some Final Notes About Organic Foods
It's important for me to note that the final product is only going to be as organic as the materials you've used (the coffee beans, egg shells, and banana peels). For those interested I'm including links concerning pesticides and how they're used for each of these items for you to educate yourself and choose what you feel is right for yourself, your family and in turn, your plants.