DIY plant fertilizers like homemade compost, vermicompost, and bokashi all make excellent options for keeping your indoor plants healthy, happy, and thriving. Plus, they reduce household waste, save money, and put all those nutrient-dense household scraps that usually end up in the trash to good use.
Here, I’ll explain everything you need to know about indoor plant fertilizers and break down the different ways you can make your very own homemade fertilizer.
why should you make your own plant fertilizer?
There are many benefits to making your very own plant fertilizer. First, homemade plant fertilizers are very inexpensive to make. Indoor gardeners can simply use food scraps and garden waste to make high-quality fertilizers that your indoor plants will absolutely love.
For this reason, homemade plant fertilizers are great for reducing household waste. Instead of throwing away nutrient-dense components from your home, with a little know-how, you can start making great fertilizer absolutely packed full of essential trace elements and minerals in no time at all.
Another tremendous bonus of DIY plant fertilizers is that they’ll contain a diverse collection of microbes thanks to the relatively high content of organic matter. Beneficial bacteria and mycorrhizal fungi all play a role in making DIY plant fertilizers. The organic matter that is used in this process creates conditions that these mutualistic microbes thoroughly enjoy. As a thank you, they’ll continue to live on in the soil once you’ve applied your homemade fertilizer, benefiting the health of your indoor plants. Use this potent fertilizer to rescue yellowing plants and boost their overall wellbeing. You’ll definitely love the results!
what do you need to make a DIY plant fertilizer for indoor plants?
There are several methods that you can use to make DIY fertilizers from the garden waste, fruit, and vegetable scraps that you’d otherwise throw into the trash. I’ll briefly list the different techniques and the equipment you’ll need below, and you can pick your poison.
With a compost bin, you can quickly and easily start your own compost pile. Compost is great for decreasing methane production, a by-product of landfill, and instead terrific at producing humus – a great addition to potting soil.
Bokashi is a Japanese term that translates to “fermented organic matter” and is typically referred to as a bokashi bin. Bokashi bins are composting bins that make use of anaerobic bacteria which break down food scraps and other organic waste.
The process only takes a week or two before the bokashi will start producing bokashi juice, a homemade liquid fertilizer tea that can be used on indoor plants. The remaining organic matter can then be added to a compost pile or thrown into the trash.
A worm farm is a composting system used to cultivate earthworms to produce vermicompost, a nutrient-rich organic fertilizer. In this system the worms eat organic waste, which is broken down by bacteria in their gut to create a nutrient-rich, low odor compost.
Worms also produce a liquid called worm juice. Worm juice can be used just like bokashi juice, as a liquid fertilizer.
Using a large container or large glass jar, indoor gardeners can make their own compost tea. Compost tea is a natural fertilizer made using compost, water and a natural culture of microbes – similar to how bokashi is made. The microbes used for this fertilizer are bacteria, protozoa, and fungi, which can be bought or made at home.
Compost tea is created by combining water with compost, but the mixture also needs to include an inoculant and a source of aeration. Compost tea provides the same benefits as compost but with additional microbial components to help improve soil quality.
Aquarium water can be used as a plant fertilizer, as it contains nitrates and phosphates, two of the most important nutrients for plant growth. The chemicals in the tank, usually from fish waste and leftover food, can act as an organic fertilizer that helps plant growth.
Waste materials from the plant roots – mainly nitrogen and phosphorus -are taken up by the fish, which convert it to ammonia and nitrite. These waste products are then converted to nitrate by bacteria living in the tank, which is available to plants.
Aquarium water is also good for plants because it removes toxins like chlorine and ammonia.
DIY plant fertilizer recipes
No matter if you have a large indoor collection or wish to fertilize your whole garden, the king of all homemade fertilizers has to be the good old trusty compost bin. No matter what it is, it can most likely go into a compost bin. Anything from grass clippings to fresh manure, to eggshells, coffee grounds, fireplace ash, or any other organic matter will do just fine in a compost bin.
What you’ll need
- Compost bin
- compost starter (unnecessary but it will speed things up)
- If it isn’t a tumbler bin, something to turn the compost with (a shovel or pitchfork will do the job)
- Start your composting process on the bare ground. To encourage worms, other garden invertebrates, and soil borne microorganisms to take advantage of your new compost, it’s best to start it on bare earth. That way, they can wiggle and squirm their way up into all the juicy food scraps you have waiting for them.
- Next, place a layer of brown (carbon). Start your compost by making the first layer a base of straw, cardboard, leaf matter, or twigs and sticks.
- Alternate the layering. On top of your brown, add a green layer (nitrogen) of organic matter like food scraps, fresh garden prunings, or grass clippings. Then alternate back to brown, then green, then brown, and so on. By doing this, you’ll ensure you are getting an equal amount of both carbon and nitrogen in your compost. Too much either way and the compost won’t be as effective.
- Keep compost moist. Compost requires the addition of water. Not too much, just enough to keep things ticking along and decomposing nicely. You can either water it yourself or allow nature to do the hard work by opening the compost bin’s lid when it’s raining.
- Keep compost covered. When the compost is not in use or you’re not adding water, be sure to keep it covered. This will both prevent it from becoming too wet from heavy rain but also ensure that adequate amounts of warmth are trapped within the center of the compost. Compost requires heat to decompose at a fast rate. So the hotter it becomes, the quicker you’ll be able to apply it to your plants.
- Turn your compost. If you aren’t using a tumbling composting bin, you’ll have to turn it every 2-4 weeks. A shovel or pitchfork will do the trick. Simply pull the compost bin off the compost pile, move it to another location nearby, and shovel the pile back into the bin. If you don’t turn your compost, it will become anaerobic (meaning, not aerated or under conditions with little to no oxygen and airflow). Sure, compost will still decompose under anaerobic conditions, but it will be much, much faster if it gets the odd turn.
- Go forth and fertilize. Depending on the size of your compost bin, what went into it, and how often you turn it, a compost can take anywhere between a few months to up to a year or so before it’s ready. Using compost too early, something referred to as “green compost”, could harm your plants. So be sure to allow the compost to break down. Compost is ready when it acts like soil. It should be a rich brown color, smell like earth, and crumble in your hand.
Our experience: Having a compost bin was great for reusing food scraps. Rich earthy soil definitely came out the other end, but it took a very long time to get started. This is a long process so likely isn’t good for anyone who is transient or renting a small space.
homemade fertilizer without ammonia – bokashi
Bokashi is a great way to make your very own fertilizer without ammonia. Ammonia within the soil captures and binds airborne nitrogen, making it available to plants. As important as ammonia is in fertilizer, some indoor gardeners wish to avoid the synthetic ammonia that is added to chemical fertilizers and, instead, recruit the help of microorganisms to produce it naturally.
What you’ll need
- Bokashi bin
- Liquid bokashi spray or compost starter
- Fruit and vegetable scraps
- Purchase a bokashi bin with a bokashi starter. Unlike benchtop compost bins, bokashi bins have been designed purposefully for brewing bokashi. Bokashi bins have a specialized grate nestled within them that gives room for decomposing banana peels and other kitchen scraps to release their juicy goodness. These bins also have a tap located that is used to drain this bokashi juice.
- Use the liquid spray or compost starter. A bokashi kit will also come with either a liquid spray or compost starter. Both contain microbes that help the decomposition process and get your scraps to release their trace minerals and essential nutrients quickly. Either spray or sprinkle the liquid or starter on regularly. You can apply these inoculants every two-three days or once a week, depending on how often you are adding food scraps.
- Allow your bokashi bin to do its thing. Once your bin is full, allow it to sit for a round two weeks. This will give the microorganisms enough time to do their work.
- Start using your new homemade fertilizer. Once the bokashi has sat for two weeks, you can drain the juice using the tap and empty the food scraps into a compost bin or straight into a hole in your outdoor garden. If you’re applying straight to the soil, bokashi juice should be diluted to a ratio of around 100:1. Although if you’re applying it as a foliar spray, a 500:1 ratio is used.
Our experience: We were So excited to try the Bokashi, which was first recommended to us by our neighbors. When used correctly, the potent juice can be used as fertilizer on your plants. The part that I didn’t anticipate was all of the compost leftover afterward from inside the bin. We ended up tossing it into our compost bin anyway since it was still too green to use directly on plants. I suggest getting a decomposing station to let the compost continue to break down into soil over time until it resembles, well, soil. Either that, or make compost tea with it, as described later on in this post.
Worm farms are a kind of mixture between a composting set up and a bokashi bin. Worm poo is referred to as vermicompost and the leachate that runs to the bottom of a worm farm, referred to as worm juice or worm pee, is used just like bokashi juice.
What you’ll need
- Compost worms
- A worm farm
- Damp cardboard, newspaper, or coconut coir
- A piece of hessian sack or a whole newspaper
- Fruit and vegetable scraps
- Buy yourself a worm farm kit. Your best bet when starting a worm farm is to buy a specialized worm farm kit. A worm farm kit will come with a specialized worm farm container or bin that has interchangeable layers and a tap at the bottom. The kit will also come with composting worms. These little guys are smaller than their vegetable garden brothers and sisters. They are also a bright pinky-red color rather than the brownish red that your regular vegetable garden worms are.
- Set up your worm farm. Add a layer of worm bedding. First up, take the base of the worm farm and place the first story on top. Now, grab your worm bedding, a bunch of damp cardboard, newspaper, or coconut coir, and layer it across the bottom of the first story.
- Add some food scraps. Next, add a small number of kitchen scraps. Don’t completely fill the entire story up, just one corner. Maybe 1/4 or 1/5 of the space that is available. This will give your compost worms a chance to move about and not be completely covered by scraps, something that they aren’t particularly fond of to begin with.
- Add your compost worms. Gently pour your worms into the worm farm, being careful not to damage their sensitive little bodies. You can place them away from the food scraps. They’ll smell them out when they’re hungry and move their way over to it when they’re ready.
- Apply your worm blanket. Worms like to be tucked in. Most worm farm kits will come with a piece of hessian sack. If not, no biggy. You can always use another layer of newspaper.
- Take the remaining worm farm storys and place them on top. Depending if your worm farm has additional storys, take them and place them on top of the bottom story where your worms are housed.
- Take advantage of the labor of your squirmy friends. Your worms will soon begin to munch away at the food scraps you feed them and quickly create a soil-like material that they’ll enjoy living in. Keep adding scraps and building out the first layer. Once it’s relatively full, start adding food scraps to the upper layers. They’ll make their way up there when they are ready and begin feeding. In only a couple of weeks, you’ll have worm juice that’s ready to use. And in only a short period after that, you’ll have fresh vermicompost that you can start adding to your potting soils.
Our experience: This is by far our favorite way to fertilize plants. The worms turn food scraps into what is basically fresh soil within a matter of weeks. Plus, it’s kind of like having pets. They grow on you and you start getting excited about feeding them little treats.
easy homemade fertilizer – compost tea
A compost tea is an organic liquid fertilizer that is created by adding compost to cold water, letting it steep for a few days, and then filtering out the solids. The liquid creates a nutrient rich solution that can be sprayed on areas of plant life or poured around root zones.
What you’ll need
- 5-gallon bucket or similar large container (if you’d like to make a small batch, a large glass jar will do the trick)
- Non-chlorinated water (rainwater works best)
- 1-2 cups of bacterial inoculant (a handful of compost or vermicompost will do the job)
- A handful of garden soil (optional, but garden soil will add beneficial soil borne microbes)
- An aquarium aerator
- Seaweed fertilizer or extract (available from any good gardening center)
- Collect your brewing ingredients. Compost teas are typically created with kitchen scraps like banana peels, garden soil, finished compost, shredded paper, animal manure, and tea bags. So start collecting, as you’re going to need them to make your brew. A bacterial inoculant like garden soil, compost, or vermicompost will be the catalyst your compost tea needs to start its fermentation process.
- Fill your container with cold water. Once you’ve got all your brewing ingredients ready to go, it’s time to fill your container with cold water. If the weather has been dry where you’re living or you’d prefer not to collect rainwater, simply let a bucket of tap water to sit for a few days. This will allow many of the toxins like chlorine to release. Chlorine kills beneficial microorganisms that your compost tea will need to brew properly.
- Place your brewing ingredients in the water. Either place the brewing ingredients straight into the water or place them in some sort of satchel, like a large cloth bag. If you opt to put the scraps straight into the water, you’ll just need to strain it before using it on your plants.
- Set up your aquarium pump. The final step, place your aquarium pump into the container and kick off the brewing process. The air pump will aerate the water and keep your little microbe friends fed with oxygen.
- Sit back and wait. Now, all there is left to do is to wait 24 hours for tea to do its thing. The finished product should look like a rich, foamy brew. The foam indicates that all the nutrients and beneficial microbes are ready to do their magic for your indoor plants.
This one is pretty self explanatory. If you have a freshwater fish tank set up, when you change the water be sure to use it on your houseplants. Aquarium water makes excellent fertilizer and plants love the nutrients that are contained within it. So much so, they’ll thank you with robust growth and beautiful green leaves.
How often should you use homemade fertilizer?
It can be super easy to over fertilize indoor plants, particularly with homemade plant fertilizers that are extremely variable in the amount of nutrients they contain.
Timing (how often)
Depending on what it is you are using, it is important to get the timing of your fertilizer applications right.
- Compost. Compost can be used as both a fertilizer and a component of potting soil. It’s best to use small amounts as it can be quite strong. Ideally, compost should only be used only a couple of times a year.
- Bokashi. Bokashi juice is quite subtle when diluted correctly, so it can be used rather frequently. In fact, everytime you brew a new batch of bokashi juice you should be fairly safe applying it to the houseplants that you think could use a feed – so every 2-3 weeks.
- Worm juice and vermicompost. Diluted worm juice is very similar to bokashi juice, it can be applied fairly regularly as long as the mix isn’t too potent. Vermicompost isn’t as potent as compost but still should be used sparingly as some plants will absolutely love the added nutrients but some may find it too strong.
- Compost tea. Compost tea can be used rather similarly to worm juice. Every 2-4 weeks it can be applied, particularly during the growing season.
How much fertilizer
Be sure to dilute your worm juice, bokashi juice, and compost tea down to an appropriate ratio.
- For worm juice, that’s a 1:1 water to worm juice ratio.
- For Bokashi, that’s a 200:1 water to bokashi juice ratio.
- For compost tea, that’s a 10:1 water to compost tea ratio.
One way to ensure you aren’t over-fertilizing or even under-fertilizing is to use a soil test kit. A soil test kit will give you insight into whether or not the soil mix you are using for your indoor plants holds adequate amounts of essential nutrients.
Things to watch out for
If you’re overfertilizing, your indoor plants are sure to let you know. Some signs of overfertilization include:
- Yellowing and wilting of a plant’s lower leaves.
- Browning of a plant’s leaf margins and tips.
- Dropping leaves or defoliation.
- Deformities like leaves curling or growing in strange, irregular shapes.
- Death of seedlings.
The bottom line
Your indoor plants will absolutely adore homemade plant fertilizers if they are made correctly. When plants are properly fertilized, it increases their resistance to diseases, helps them grow faster, flower more vigorously and look healthier.
And really, that’s all we really want for our plant babies, isn’t it?
more about fertilizing
- 10 best plant food options for indoor plants (for every kind of plant)
- homemade phosphorus fertilizer: the easiest all natural diy fertilizer in your kitchen
- zz plant fertilizer
- your guide for how often to fertilize indoor plants
- fertilizer burn: what you need to know
- how to test soil ph with a ph meter
- make a DIY indoor worm composting bin in 4 steps