Fermented Fertilizer

I’m going to take a break from flogging about the balcony garden this week to discuss a technique I use to execute Gil’s recipes in my small scale environment. You don’t always need to ferment on a large scale, with tons of plant material. If you have a small outdoor space like me, that’s not feasible. But the great thing is, even with limited space you can still use these recipes to make your own fertilizers! It’s the idea of “micro-fermentation”.

I have two balconies in my little urban apartment. One holds my urban garden while the other is an eclectic mix of plants, animals, experiments and other weird stuff I’ll talk more about later. In this space, I have limited plants to choose from. I won’t end up with a kilogram of plant material to work with, more like a couple grams.

But even in my small farmyard, I’ve noticed some fast-growing weeds, and even cultivated them a little to make my “micro-extract”. These fast-growing vines will be perfect for my growth promoter extract:

Fermented Fertilizer - Part 1

Start with fast growing plants

You want to select the fastest growing part of the above-ground plant – the tips. So now I select the growing tips:

Fermented Fertilizer - Part 2

Select the growing tips of the plants

Once I’ve cut a bunch of tips, I’ll have a lot from each plant. Still nothing compared to what you would find on a “real” farm.

Fermented Fertilizer - Part 3

Collection of growing tips cut from my fast growing weeds

Now to put them in a little container. TIP: You can find little plastic containers pre-labelled at just about any pharmacy anywhere – specimen jars! They make perfect mini-fermenters!

Fermented Fertilizer - Part 4

Plant material to be fermented

Now that I have all the plant material in the container, I pulverize it a bit to break down some of the tougher material . This step isn’t necessary but I think it helps with extraction.

Fermented Fertilizer - Part 5

Mash the growing tips to help with extraction of nutrients

Add 1/3 part sugar, in this case molasses, the favorite sugar source of natural farmers here in the Philippines. I didn’t measure this out, just eyeballed it. I’m a farmer! If it’ll get the job done, it’ll work.

Fermented Fertilizer - Part 6

Add roughly 1/3 part sugar – no need to be exact

Now add the secret sauce. You don’t have to do this but it greatly speeds up/enhances fermentation if you do. Add a couple drops of lactobacilli serum. Don’t need much at all especially in a container this size.

Fermented Fertilizer - Part 7

Add lactobacillus to speed up fermentation

Finally, fill with water. Fill to near the top, screw the cap on but don’t seal it as some gas will form during fermentation. Then date and name it accordingly on the handy little label that came on the container.

Fermented Fertilizer - Part 8

Fill with water – this comes to about 3 parts water in this container

This will be good for a few feedings later on when I need to fertilize and want to add some growth promoting hormones, enzymes, etc.

You can tighten the lid when you see bubbling stop after several weeks. You will also notice the smell as it finishes fermenting. It should smell a bit like vinegar. That is the acid that is a byproduct of fermentation. Here’s what it looks like after 3 weeks:

Fermented Fertilizer - Part 9

After several weeks, the bubbles are gone and the plant material is noticeably degraded

This was stored in a dark place and just left alone with the lid cracked for 3 weeks. I checked it periodically, you will see the bubbles on the sides each time you check, signs that it is indeed fermenting. I would usually tighten the cap and give it a shake but this isn’t necessary really. After 3 weeks (actually a lot sooner this time, but leaving it longer doesn’t matter), you’ll stop seeing bubbles on the sides, and the smell will be like alcohol/vinegar/sour – the fermented smell.

There you have it, your own little mini-extract! The whole process takes 5 minutes and I end up with a great product. I’ll mix this with my homemade fish fertilizer, and use that on the garden when I want to feed in the future. The fish fertilizer provides the Nitrogen while this extract provides the growth promotants. Great combination.

Those familiar with the Grow recipe will notice that I added water, where the recipe doesn’t call for adding water. That’s how I adapted the recipe for this small scale use. It will be a little more diluted than if I hadn’t added water, but there wasn’t enough plant material to do it that way. As long as you stick to the principles of the recipes, you can adapt them depending on your situation, like substituting pumpkin for papaya in the bloom recipe, or snails for fish in the fish fertilizer recipe.

What have you been fermenting? How has it worked out for you? Share with the group in the comments section!

  • Tony McDonald

    Here in Thailand we get lots of golden apple snails, big ones. I will try using them in the fish fertiliser if I can get hold of some. The locals usually have on the fire and eaten whilst working in the fields. Their shells go in to CalPhos.

    • Patrick

      Yeah exactly.. use the meat for the fish fertilizer recipe and the shells for calphos. That should work out well.

  • Karen

    Hi patrick,

    How often do you spray the ferments on to the plants and are they all foliar? I have not come across intructions on frequency of application.


    • Patrick

      Hey Karen,

      Great question. There is no rule on this. I would say as much as needed. I won’t need it for many weeks as my soil has plenty of nutrients in it for right now. In a month or two I will start spraying twice per month. If it feels like the plants need more, I’ll spray every week. You could spray every day though and it shouldn’t be a problem, that’s just too much work!

      You can use as a foliar spray or soil drench. Just make sure you dilute as directed in either case.


  • Mike Landry

    hey Patrick,
    thanks for all the great info. I have been a busy bee making almost everything

    • Patrick

      That is awesome! Me too 🙂

  • Ralph

    Hi Patrick and fellow gardeners. Am taking first my steps in organic gardening. Have been making compost tea, made lacto serum this week and will start using it. I want to make this growth promoter and wondered if I can put weed tips in blender and after the fertilizer is made, how do I store it and how long will it last?

    • Patrick

      Weed tips will work well. Grass clippings work well also. You can store it for a long time in sealed container. After fermentation it is very stable, can be stored in sealed container for a year, longer.. If you’re opening it a lot and introducing air, it will start to go bad after awhile – store in fridge to combat that, or use it quickly once opened.

  • Kara

    How about the fermentation of golden apple snail extract? How can i do it?

    • Patrick

      Hey Kara,

      Follow the recipe for fermented fish fertilizer. I’d separate the meat from the shells, use the meat in the fish fertilizer recipe and use the shells in the calphos recipe.


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