Best Organic Fertilizer for Houseplants

Using natural and organic fertilizers to boost plant growth is an age-old technique. You want nothing but the best for your houseplants – this means no harsh synthetic chemicals.

The best organic fertilizers have the perfect ratio of macronutrients. They are easy to absorb and improve soil structure. More importantly, they don’t contain harsh chemicals. This article looks at the best organic fertilizers for houseplants in California.

Organic Fertilizers for Houseplants

Several types of organic fertilizers can be made right in your garden.

Banana Peels

Banana peels are available and can be bought at any grocery store. Instead of discarding the banana peels, you can use them as organic fertilizers.

They contain a lot of potassium and small amounts of nitrogen and phosphorus. Other micronutrients include magnesium and calcium.

In this sense, banana peels act as slow-release natural fertilizers. There are several ways of using them.

Banana peels can be placed over the potting soil. Worried about the smell breaking loose in your room? You can contain the smell by covering the peel with some soil.

Another idea is to cut banana peels into smaller pieces or blend them with water. These pieces are mixed into the soil before potting a new plant.

Blending with water creates a rich, easily absorbable liquid fertilizer for your plant.

Best Organic Fertilizer for Houseplants
Best Organic Fertilizer for Houseplants


Eggshells are a popular choice for indoor plants. They are naturally rich in calcium and are often used to reduce soil acidity.

Eggshells contain high reservoirs of various macronutrients like phosphorus to help houseplants in California grow.

But don’t just dump eggshells onto the soil. There are a few things you should keep in mind. The first step is to remove the inner membrane of the eggshell.

Then you can wash the egg shells before allowing them to dry. Now crush the eggshells to mix them into the soil.

Another popular strategy is to soak them in water overnight. This mixture can be used as a liquid fertilizer for houseplants.

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Kelp only contains a small amount of nitrogen. But that’s not why we’re using it for your houseplants.

The real advantage of using kelp is that it improves soil development. This allows your houseplants to thrive and enhances their growth rate.

Kelp also improves the resilience of your houseplants so they can survive extreme temperatures. If your location is prone to frequent bouts of first, consider using kelp.

Kelp can be purchased from any garden center near you. You may also buy some and compost them yourself. The latter will save money.

Alfalfa Meal

Alfalfa meal is an organic fertilizer that contains a small amount of potassium and nitrogen. But its real benefit is that it improves soil health.

This, in turn, boosts your plant’s growth rate over a period of time. It works exceptionally well with flowering houseplants.

Chicken and Cow Manure

For this one, you might have to get your hands dirty. If you’ve got livestock in your backyard, you can use manure to boost plant health.

Manure from livestock such as chicken and cow is incredibly rich in nutrients. They can feed soil and plants alike.

Do not apply the manure directly to your plants. This will burn them and cause irreparable damage.

Instead, it would be best if you composted the manure properly. Alternatively, you can buy the manure in pellet form. This way, you won’t have to get your hands dirty.

Just make sure that the fertilizer comes from free-range farms. This ensures that the fertilizer has excellent organic and nutritional value for houseplants in California.


When they’re not busy making your skin crawl, worms can be found helping the ecosystem. These forbidden noodles are highly efficient at processing your leftover food into delicious liquid tea.

You can make worm farms in your own backyard – if you have enough space. Another alternative is to create an indoor compost bin.

This bin can be used to break down kitchen waste using beneficial bacteria. Either way, you will

get access to a nutritious liquid for use with houseplants.

Leftover Cooking Water

When you’re done boiling food with water, don’t discard the utensil yet. This water is teeming with nutrients that houseplants crave.

Once you’re done meal prepping, allow the water to cool down to room temperature. Now dump the water into houseplant soil for an instant boost to their health.

Coffee Grounds

Your coffee ground can be used for more than just beverages to power your mornings. You can use coffee grounds, or what’s left of them, to fertilize houseplants.

Mix a spoonful of coffee ground with the potting mix before planting. You can also mix water with coffee grounds and use the liquid to water houseplants.

There are a few things you should note. Coffee is acidic. So it will make the soil slightly more acidic.

We recommend using coffee grounds on houseplants with acidic soil. Examples include jade plants, African violets, and cacti.

Fish Tank Water

You might think that fish tank water covered in fish poo is gross for houseplants. But you would be surprised just how nutritious the water is for houseplants.

The water is rich in nitrogen, potassium, and other nutrients from fish waste. So the next time you decide to clean your aquarium, don’t discard the water.

Use it on your houseplants in California instead.

Epsom Salt

Epsom salts are rich in sulfate and magnesium. Both nutrients go a long way in keeping your houseplants heathen.

Making Epsom salt fertilizer is very easy. Dissolve a small amount (one teaspoon) of Epsom salts into 1 liter of water.

Now spray a small amount of the fertilizer on the topsoil.

Green Tea

Don’t worry; your houseplants will not deplete your supply of green tea. Use the leftover used tea bags to create a delicious houseplant meal.

The process is relatively straightforward. Empty the green tea leaves and place them over the soil – and that’s it!

You can brew the tea with water to create a liquid fertilizer for your houseplants. Note that green tea will make the soil slightly acidic.

Make sure that your house houseplants prefer acidic soil before introducing them to green tea.

Things to Consider When Choosing a Fertilizer for Houseplants

Several factors go into fertilizer selection. A key aspect of choosing fertilizers is the type of plant. This section takes a look at some of these factors.

Plant Species and the NPK Ratio

The NPK ratio is a term that you are likely familiar with. It is a short form for nitrogen (N), phosphorus (P), and potassium (K).

Nitrogen is crucial for plant health and aids in the development of chlorophyll. It is an essential component of cell walls and DNA in plants.

Plants with a nitrogen deficiency will have stunted growth and turn yellow. Phosphorus helps with blooming and root growth.

It is also helpful in improving water transport and photosynthesis. This makes it indispensable in keeping a houseplant healthy.

Potassium regulates stomata openings for gas exchange and improves water intake. It also aids in the development of fruit and flowers. More importantly, potassium allows plants to resist diseases and pets.

Plants lacking in potassium will show symptoms such as stunted growth, wilting, and yellowing leaves.

Different fertilizers contain a mix of macronutrients in different ratios. For example, a balance of 10-5-10 represents 10% nitrogen, 5% phosphorous, and 10% potassium.

A higher percentage of nutrients will make the fertilizer more potent. There’s no such thing as a ‘perfect’ NPK ratio because every houseplant species is different.

In general, greener houseplants in California required a balanced NPK ratio, slightly favoring nitrogen.

Flowering plants such as oxalis and peace lilies prefer a higher phosphorus balance. The macronutrient speeds up the yield rates of fruit and edible plants.

In general, the following NPK ratios are ideal for most houseplants in California:

  • 1-1-1
  • 2-2-2
  • 15-15-15
  • 14-14-14

The table below looks at popular organic fertilizers and their NPK ratio.

Organic FertilizerNPK RatioUses
Organic cottonseed meal6-3-2Ideal for slow-release applications and keeps the soil aerated.
Organic alfalfa2-5-2Contains naturally occurring growth hormones and boosts the growth rate of juvenile plants.
Bone meal5-5-6Ideal for fruiting and flowering. It is also used for transplanting.
Fish meal10-6-0A great source of nitrogen and other micronutrients. It is an excellent soil conditioner.
Green seed0-2-5Contains potassium, magnesium, and iron. It does not contain nitrogen. Greensand is ideal for increasing root growth and moisture retention in plants.

Always consult the care guide of your houseplant species for specific instructions on NPK ratios.

Organic Certification

How can you know that the fertilizer is ‘organic’? Anyone can slap the organic label on a product that isn’t organic.

Usage of the word organic is not regulated by houseplant fertilizers. So you are on your own and should do your due diligence when buying fertilizer.

A safe bet is buying products that contain the Organic Materials Review Institute (OMRI) seal.

OMRI is a well-respected institution that awards certification to products that comply with USDA. This does not mean that products that don’t contain the OMRI seal aren’t organic.

Fertilizer Application   

In general, you want organic fertilizers to be easy to apply. This depends on whether the fertilizer is a liquid, granular, or slow-release formula.

Granular fertilizers take much longer to break down. They are sprinkled over and 3 inches under the soil before being watered. This will release nutrients to the plant.

Be careful not to over-fertilize your houseplants with them. Granular fertilizer is often used when planting the houseplant for the first time or repotting.

They must be reapplied every four to six weeks. Always consult the manufacturer’s instructions for application guidelines.

Liquid fertilizers provide a quick nutrient boost to your plant. You might want to dilute them if your manufacturer requires you to.

It is easy to apply liquid fertilizers. Just put them in a spray bottle and spray on the plant leaves. You can also pour the fertilizer onto the soil.

Dilution is key to avoiding over-fertilization of the plants. Spraying with liquid fertilizer is easy and ideal for many houseplants.

Liquid fertilizers should be applied to houseplants once every 1 or 2 weeks.

Slow-release fertilizers, as the name suggests, act over a period of time. They provide a constant supply of nutrients to plants.

The exact method of application depends on the specific product. A popular choice for slow-release fertilizers is to use banana peels (discussed above).

A Brief Word on Mycorrhizae

Providing nutrients to your houseplants doesn’t end with fertilization. The real magic happens when billions of microorganisms process fertilizer into usable nutrients for houseplants.

Mycorrhizae is one such group of organisms. They are the root system of many fungi species that thrive in healthy soils.

Mycorrhizae form a symbiotic relationship with the plant’s root system. They facilitate water and nutrient uptake in the plant.    

Meanwhile, the plant provides nutrients and food to the Mycorrhizae through photosynthesis. In this sense, mycorrhizae can be likened to a beneficial microbiome in animal guts.

You can buy Mycorrhizae and add them to the topsoil to boost nutrient intake. They are referred to as inoculants. Most people apply inoculants at the seeding and transplanting stage.

What’s the Difference Between Organic and Chemical Fertilizers?

Plants don’t really care where the macronutrient is coming from. You can, however, provide them with higher contractions of macronutrients using chemical fertilizer.

However, organic fertilizers are cheaper and abundantly available. They can mitigate many problems associated with chemical fertilizers.

Chemical fertilizers, like junk food, make your plant feel great for a very short period. They are ideal in the short term but require several applications.

Chemical fertilizers can leave your houseplants depleted and require more.

Organic fertilizers also reduce the frequency of application to maintain soil fertility. They significantly improve soil structure, aeration, and texture.

Organic fertilizers come from various sources, including animal sources, leftovers from food, plants, and others.

Wrapping Up

So there you have it, a quick look at the best organic fertilizers for houseplants. The article also discussed a few best practices for choosing suitable organic fertilizers.

So how do you fertilize your houseplants? Share your experiences with us, and we might update this space with your advice.

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