5 Zero Waste & Free Plant Fertilizers
Why Does Fertilizer Matter?
When you buy a plant from a store or just repot it, you’re using soil that’s been packed with nutrients that your plant needs to grow. Yes plants pull energy from the sun and water from us, but they need other things in order to grow. That’s like us trying to live exclusively on bread and water. Sure we’d live for a while, but we’d get pretty frail and malnourished along the way. That’s why we have to keep adding nutrients into the soil to literally keep feeding them.
Different species pull different things from the dirt, but the primary nutrients are nitrogen, calcium, phosphorus, potassium, magnesium, and sulfur. The main three are known as NPK: nitrogen, phosphorus, and potassium. The term you hear often in farming is “nitrogen depleted soil,” which means that whatever crop was growing there was sucking out nitrogen faster than it could be replenished. On larger scales, rotational grazing, rotational crops, and fertilizers are the typical solution to this problem. Some species help bring more nitrogen back into the land, like clover, while animals bring the option of bring the NPK back to the land through their manure.
I don’t know about you, but my potted indoor plants don’t have the surface area to sustain an entire sheep for rotational grazing. Instead, I supplement my green children with fertilizers. Until recently, I used to use the generic Home Depot chemical indoor plant fertilizer. To be fair, it worked great. But one day I ran out and didn’t want to go to the store, so I started doing some research on some DIY fertilizers.
Keep in mind: we’ve managed to get some affiliate links for some of these products, so we get a small kickback for the purchases made on those sites denoted by an ‘*’.
Why These Methods Avoid Composting
I know composting is the ultimate natural fertilizer, but the reality is that many apartment-dwellers don’t really have that option. Countertop composters exist, but they can range anywhere from $50-$200+ and I just don’t have the extra resources to dedicate to something I might find myself forgetting about during my day-to-day life. Besides the barrier to entry, a lot of countertop composters are too small to really take advantage of the food scraps we produce and are in the habit of smelling not the best in a rather small space.
If you’re looking to compost and you don’t have a garden, try signing up for city composting programs that work similarly to a routine garbage-day pickup! It’s a great way to make sure your scraps aren’t just finding their way to the dump and are being reutilized in a productive and eco-friendly way!
That being said, non-compost fertilizers are easy to make on a whim and easy to store in the fridge. Most of these methods we’re going to talk about in this blog post are water-based methods, meaning it uses water to extract the nutrients from the various food waste elements in order to easily add them to your normal watering routine.
Things You Probably Have
1. Egg Shells
Helps with: Acidity moderation, strengthening cell walls, promoting healthy growth
Contains: Calcium carbonate, potassium, phosphorus, and magnesium
Egg shells contain a lot of great things for your green children, the most prominent being Calcium in the form of calcium carbonate. The only problem is that calcium carbonate isn’t water soluble, meaning it won’t just leech into the water all by itself. You have to kickstart the reaction either through high heat or through a chemical reaction. We’ve included both methods for whatever you have on hand in your kitchen! This is all about using up all those food scraps based on what you have laying around.
How To:
Rinse your eggshells with cold water.
Crush your eggshells into small shards using a mortar and pestle, or in a plastic bag using a rolling pin.
In a heatproof jar, add your eggshells and fill to the top with boiling water. Allow to sit overnight or up to a week, and then use alongside your usual watering routine after straining.
OR
3. Just submerge your eggshells in brown rice vinegar or apple cider vinegar until it bubbles stop forming. This means that your eggshells have been saturated with the vinegar. Strain out your eggshells and add to a jar. Fill jar with water and allow to sit 2 or 3 days, up to a week.
4. Use alongside your usual watering routine after straining!
2. Used Coffee Grounds
Helps with: Pets digging in dirt, beneficial microorganisms, water retention, pale leaves, slow growth
Contains: nitrogen, calcium, potassium, iron, phosphorus, and magnesium
In an outdoor garden they can also be used to attract worms and repel pests, but for indoor container gardens they’re just generally used for a nutrient injection. Be mindful of where you’re using this, though, as it can really boost the acidity levels of your dirt. Plants like pothos, rosemary, and orchids are very sensitive to pH changes in their soil and do particularly badly with acidic soil.
How To:
Mix dried grounds in with soil while repotting
OR
Sprinkle coffee grounds onto the top of your soil or in the water tray
OR
Just use a bit of the leftover coffee in your pot that you’re going to pour down the sink anyway on your acid-loving plants
3. Old Banana Peels
Helps with: Brown scorched leaves, curling leaf tips, slow growth, and yellowing between plant veins
Contains: Potassium, calcium, magnesium, sulphur, phosphorus
How To:
Cut up banana peels and add to heat proof wide-mouth jar with a lid.
Soak in water for 2-3 days to extract nutrients OR Add banana peels to a small saucepan of boiling water for 30-45 minutes
Strain and discard used peels and store
Use as part of watering routine until your banana water has been used up
4. Onion Scraps
Helps With: Disease resistance, slow growth, stem strength, contains natural rooting hormones
Contains: Calcium, magnesium, sulfur, phosphorus, and potassium.
How To:
Take 2 large handfuls of onion skins and offcuts, then add to around 4 cups of water to extract nutrients
Wait 24 hours, then strain and use alongside your regular watering schedule
5. Rice Water
Helps With: Pests (if fermented), increasing soil acidity
Contains: Nitrogen, phosphorus, potassium, calcium, iron
The process of washing rice is to remove the starch from the outside of the grains. This starch keeps the rice from getting fluffy and makes it stick together. Most of the time we just dump this excess down the sink, but it’s actually a great way to get some great nutrients into your soil. Be aware that like coffee, the heavy amount of nitrates (nitrogen) in rice water can decrease the pH of your soil, making it more acidic. Some plants respond very badly to these types of changes, so be mindful of what you’re feeding when it comes to this method.
How To:
Save the starchy water from washing your rice
Use alongside your regular watering schedule, only for plants that like acidity
Easy Storage
Once you have your miscellaneous jars of natural fertilizer, make sure you’re labelling and dating them! You don’t want to mix up something like that in the back of your fridge, only to find it again months later. Never a good time, and I’ve done it more times than I can remember. My life changed when I finally bit the bullet and just got a cute label maker. Way easier, and actually very cute to look at. I also recommend using wide-mouth mason jars, as these tend to be heat proof and have excellent mouth seals. They also stack and store pretty easily in the fridge, which is always a plus for me.
Another reason to label your different fertilizers is to make sure you’re not mixing them up. As mentioned in the Coffee section, some plants are very, very sensitive to pH and nutrient changes to their soil and mixing up your fertilizer could potentially hurt or hinder your more delicate houseplants.
We also recommend using your fertilizers in moderation to avoid drowning your plants in nutrients, which can also hinder their growth. Consider just adding a splash of whatever fertilizer you choose to your weekly watering routine.
Be aware, while we do like these products, we have affiliate links set up for most of them. That means we get a little kickback if you decide to get any of these products through our website.
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I don’t know about you, but my potted indoor plants don’t have the surface area to sustain an entire sheep for rotational grazing. Instead, I supplement my green children with fertilizers. Until recently, I used the generic Home Depot indoor plant fertilizer. To be fair, it worked great. But one day I ran out and didn’t want to go to the store, so I started doing some research on some DIY fertilizers and here are my favourites!