Best Indoor Plant Fertilizer 2021: Reviews, Buying Guide, and FAQs

by Izaz Ahmad

Is there a "best fertilizer for indoor plant"? Can I Use any type of fertilizer when starting an indoor garden? There is so much to think about where indoor fertilizers are concerned.

Depending on who you ask, you might frequently hear experts and causals alike refer to fertilizers as plant food. And while there is just a bit of truth in it, this notion isn't entirely correct. The fact is, the only process plants get their food is via photosynthesis. Of course, you are probably already familiar with the term and the process involved during photosynthesis.

So when plants already have a guaranteed source of food for healthy growth, why then is the need for Fertilizers?

Top Indoor Plant Fertilizer 2021 by Editors

This is an interesting question but also quite technical to answer. Asides from the nutrients plants get from photosynthesis, they also need some crucial nutrients (both macro and micronutrients) that are important in the synthesis of critical enzymes as well as important defense mechanisms.

A good way to explain this is by looking at photosynthesis and fertilizers like the way humans get food and nutritional supplements. In other words, you can see photosynthesis and other natural processes plants use in getting their food as the normal main course including appetizers and veggies. Then fertilizers are simply the nutritional supplements plants take, that though not ultimately important, are still very important.

That said, fertilizers are much more than nutritional supplements plants as aforementioned. This is because the Sun, which is the major and optimal part of every plant's food-making process, is not always up. Plants need to survive all day long, especially when they are not in their native or natural environment.

Indoor Plant Fertilizers are just a type of fertilizers which as the name implies are best for indoor farming.

Unfortunately, there are different indoor plant fertilizers to pick from over the counter in a local store or an online store.

To help you make great buying decisions and find the best fertilizer for your indoor farming, we have reviewed the top 10 best indoor fertilizers in 2021.

Top 10 Best Fertilizers for Indoor Plants

Top 10 Best Fertilizers for Indoor Plants
Top 10 Best Fertilizers for Indoor Plants

1. Miracle-Gro Indoor Plant Food Spikes - Link

Miracle-Gro Indoor Plant Food Spikes, Includes 24 Spikes - Continuous Feeding for all Flowering and Foliage Houseplants - NPK 6-12-6
Miracle-Gro Indoor Plant Food Spikes, Includes 24 Spikes - Continuous Feeding for all Flowering and Foliage Houseplants - NPK 6-12-6

Spikes are essentially a type of houseplant fertilizer that is more suited for long-term plants. They are mostly used on potted plants.

The Miracle-Gro Plant food spike is Miracle-Gro's attempt at creating an effective fertilizer that can feed all foliage and flowering indoor plants. It contains the basic nutrients plants needs - NPK - in the 6 - 12 - 6 ratio.

Although it is suitable for all indoor flowering and foliage plants, The miracle-gro spikes work best on Ferns, croton, spider plants, among others.

The product is easy to use. The spikes come in different packs and sizes. The basic pack, which contains 24 spikes can continuously feed your potted plants for 2 months. That said, the brand has packs that contain as many as 576 spikes on the market for sale.

For those that are not too familiar with fertilizers in spike form, each product/pack comes with a label that contains full instructions on how to safely use the spikes so they can provide plants with the necessary micronutrients they need.

TIP: To achieve the best possible results with this product, you should replace the spikes buried in their respective holes every 25-30 days during Spring and Summer. However, in Winter, since the plants are not overly active, you can leave the spikes in their holes for about 60 days before removing them.

NOTE: Spikes works like every other plant fertilizer despite their unique form and shape. You must regularly water the plants to ensure proper growth of the plants.

Highlighted Features

  • Suitable for most Foliage houseplants including Ferns, crotons, etc.
  • The basic pack, containing 24 spikes, would last about 2 months.
  • Safe to use.
  • Stimulates vibrant growth of houseplants.


  • They are quite expensive when you calculate just how many spikes you need to use by following the instructions on the label.
  • The spikes sometimes overfeed certain plants such as flowering lilies. Hence, you might need to research and be sure the spikes won't negatively affect your plants!

2. Osmocote Smart-Release Plant food for indoor and outdoor use - Link

Osmocote Smart-Release Plant Food Plus Outdoor & Indoor, 8 lbs
Osmocote Smart-Release Plant Food Plus Outdoor & Indoor, 8 lbs

The Osmocote brand is another popular brand well recognized when it comes to fertilizers for both outdoor and indoor use.

The Osmocote Smart-Release plant food is definitely high up on the list of effective granule fertilizers on the market. It contains 11 important nutrients (both macro and micro) that indoors flowering plants and foliage need to grow properly. As if that is not enough, it is also ideal for outdoor plants or herbs.

What we particularly love about the Osmocote Smart Release Plant food is that just one 8lbs box can last for about 6 months. So not only can you expect a massive improvement in your plant's growth, but but you also don't have to worry about replacing the fertilizer anytime soon.

You'll also be glad to know that this fertilizer does not burn plants when applied. That said, you can confidently apply the fertilizer to your houseplants!

Highlighted Features

  • Produced by one of the most popular fertilizer brands on the market today, it contains 11 important nutrients critical to plant growth.
  • There are no cases of the fertilizer burning plant leaves or stems.
  • Suitable for all variety of indoor plants and can be used all season
  • It easily dissolves in water which allows for easy release of nutrients.


  • While the fertilizer does work, it leaves behind small plastic shells after the granules dissolve and the nutrient is released. This is bad because, in the long run, it adds more plastic to the environment at large! The last thing we need is more plastics!

NOTE: This wasn't the case with this product before as the granules would previously completely dissolve without any trace. It is a recent change by the manufacturers which they would hopefully reverse.

3. Miracle-Gro Water Soluble (10lbs) All Purpose Plant Food - Link

Miracle-Gro Water Soluble All Purpose Plant Food, 10 lbs.
Miracle-Gro Water Soluble All Purpose Plant Food, 10 lbs.

This is another entry from the Miracle-Gro brand which just goes to show how authentic and effective fertilizers from this brand is.

Unlike the Miracle-Gro Spikes that we talked about earlier, this product is in form of granules. In other words, it is a granular fertilizer that you can apply to your plant dirt and leave to dissolve.

It is suitable for both indoor and outdoor plants, although in this case, you are only reading this because of its effects on indoor plants.

The Miracle-Gro water-soluble fertilizer comes in different sizes. To use, all you have to do is dissolve the granules in a watering can. After which, you can then water your potted plants.

NOTE: Provided you follow the printed instructions on the box correctly, you can rest assured knowing it won't burn your flowers, vegetables, shrubs, etc.

Highlighted Features

  • Makes flowers, shrubs, and vegetables more beautiful, bigger, and bountiful.
  • The effect of this fertilizer on unfed plants is noticed within 24 hours.
  • Contains NPK formula in the ratio 24 - 8 - 16.
  • Lasts all season provided you follow the instructions. It even works on city dirt i.e. dirt that contains other components such as shards of glass, paper, nylon, etc. You can expect this product to work the same way it would work in rich loam dirt.


  • Expensive for the size you get.

4. VitaSea All-Purpose Indoor Plant Fertilizer by Beanstalk - Link

Organic Indoor Plant Food - VitaSea All Purpose Indoor Plant for Indoor Plants (6 oz) by Beanstalk, Easy-to-Use Shaker, House-Plant Fertilizer Indoor Potted Plants, Natural Succulent Plant Food
Organic Indoor Plant Food - VitaSea All Purpose Indoor Plant for Indoor Plants (6 oz) by Beanstalk, Easy-to-Use Shaker, House-Plant Fertilizer Indoor Potted Plants, Natural Succulent Plant Food

The VitaSea All-purpose fertilizer is one of the best purely organic fertilizers on the market. It comes with a ton of macronutrients. The fertilizer is extremely easy to use.

One thing we particularly love about this fertilizer is that it is pet and child-friendly thanks to the constituent component of the fertilizer. This means it is not only an effective fertilizer made from purely organic ingredients, but it is also safe to use even if you have kids or pets running around in the house.

The brand claims the fertilizer is capable of promoting plant growth faster than other houseplant fertilizers in its price range. It does this by promoting strong root growth of plants which in turn speeds up the nutrient intake of the plant.

In case you are wondering, you will be glad to know that the fertilizer is suitable for a variety of indoor plants. It would work on any type of succulent plant and even plants such as monstera. For this reason, it is referred to as an all-purpose fertilizer.

Highlighted Features

  • Made from purely organic components, it is one of the best alternatives to synthetic fertilizers
  • Enriches soil and greatly promotes root growths of plants
  • Works on almost every type of houseplant you have
  • Kids and pets friendly
  • Easy to use with explicit instructions on the bottle.
  • There is no need to mix this fertilizer with water before using it. Simply sprinkle directly out of the box.


  • Although the fertilizer itself is safe to use when you have pets and kids around the house, many users complain about their pets getting attracted to the plant dirt on applying the fertilizer to the plant. This can be a bit problematic as the pet might show too much interest in the plant, thus end up damaging the plant in the process.

5. Jobe's Organics Fertilizer Spikes (All Purpose) - Link

Jobe's Organics All Purpose Fertilizer Spikes, 4-4-4 Organic Time Release Fertilizer for All Plants, 50 Spikes per Package
Jobe's Organics All Purpose Fertilizer Spikes, 4-4-4 Organic Time Release Fertilizer for All Plants, 50 Spikes per Package

Jobe's is another well-respected brand when it comes to fertilizers. It is a company based in the United States and reputed for producing quality fertilizers.

Right off the bat, you should note that the Jobe's Organics Fertilizer Spikes are formulated entirely from an organic mixture of potash sulfate, feather and bone meal. This makes it 100% organic and perfectly safe for your plants.

The spikes directly provided your plant roots with the necessary nourishment to grow bigger and greener. It works all season long and the brand even claims it has no surface runoffs!

Asides from the organic mixture contained in the spikes, each spike also contains biozome. Biozome is essentially a proprietary blend of critical microorganisms that, in the long term, improves soil quality.

Highlighted Features

  • Easy to use since all you have to do is insert the spikes into the soil by pushing it in.
  • Contains critical nutrients in the formula ratio 4 - 4 - 4; you don't have to worry about odor.
  • Slow-release fertilizer for long term


  • Although they are pet safe, your dog might find them interesting and might even try to chew them. This is something you might want to consider if you own a pet, especially a dog.
  • If not properly stored, the spikes quickly start to mold within 5 days of opening the box.

6. EarthPods Premium Concentrated Indoor Plant Food Spikes

EarthPods Premium Concentrated Indoor Plant Food Spikes (100 Count) – Easy to Use – Organic Time Release Fertilizer – All Purpose – Great for Houseplants (NO Smell, Ecofriendly, Made in USA)
EarthPods Premium Concentrated Indoor Plant Food Spikes (100 Count) – Easy to Use – Organic Time Release Fertilizer – All Purpose – Great for Houseplants (NO Smell, Ecofriendly, Made in USA)

The EarthPods premium concentrated spikes are some of the best eco-friendly indoor plant fertilizers on the market.

As the name implies, the product is in form of capsules, and a bottle contains 100 of them. The capsules are incredibly easy to use and there are no accompanying smells unlike most indoor plant spike fertilizers out there.

Thanks to its concentrated organic content, the Earthpods capsules have the necessary components to make your loamy soil rich again. Thus stimulating robust root growth which in turn leads to strong stem development and vibrant leaf color.

They are some of the best long-term fertilizers on this list since the capsules slowly release enough nutrients into the soil so that the roots can easily reach them. Each capsule contains organic essential nutrients, trace minerals, humates, etc.

NOTE: For directions on how to use it, you can check the body of the accompanying paper container. However, for the most part, you will need to push in one capsule every 14 to 21 days. The capsules completely dissolve so you don't have to worry about any plastic coating or shell being left behind.

Highlighted Features

  • Ecofriendly fertilizer for enhanced plant growth
  • Easy to use
  • Slowly release nutrients to plant roots so you don't have to regularly reapply the capsules
  • Vegan, Child, and Pet friendly


  • The Earthpods spikes is a great fertilizer for your plants since each capsule degrades slowly so that there is always nutrients available for your plant roots at all time. However, if you have a lot of plants or want to use this fertilizer for trees, this can be very costly.

NOTE: Trees require at least 4-7 capsules every 2 weeks for more effective results.

7. Miracle-Gro Indoor Plant Food (Liquid) - Link

Miracle-Gro Indoor Plant Food (Liquid), 8 oz., Instantly Feeds All Indoor Houseplants Including Edibles, 2-Pack
Miracle-Gro Indoor Plant Food (Liquid), 8 oz., Instantly Feeds All Indoor Houseplants Including Edibles, 2-Pack

This liquid fertilizer is just too easy to use. It is suitable for all indoor plants including edible plants.

The Miracle-Gro indoor Plant food (Liquid) is available for sale in three different sizes: 1 pack, 2 pack, and a plant care bundle.

You only need to apply this fertilizer once every week. You can mix the liquid with water to wet your plant with or apply the liquid directly to the soil surface without mixing.

TIP: It is highly recommended you mix this fertilizer with water instead of applying it directly to the soil. Also, regardless of the procedure, you follow when applying this fertilizer, you must water your plants heavily that is, more than you would typically water them.

Highlighted Features

  • Ready for use immediately!
  • Suitable for all houseplants including edible ones
  • Multiple ways of applying the fertilizer to your plants
  • Comes with pumps so you don't need to find any alternative dispersion method


  • You need to water your plants heavily after applying the fertilizer for optimal results
  • The plastic pumps it comes with are pretty cheap and can quickly spoil.
  • NOTE: Although the brand advertises 2 packs in one of the size options, you will only get one bottle on delivery.

8. J.R Peters 52024 Jack's Classic No.1.5 20-20-20 Fertilizer - Link

J R Peters 52024 Jacks Classic No.1.5 20-20-20 All Purpose Fertilizer
J R Peters 52024 Jacks Classic No.1.5 20-20-20 All Purpose Fertilizer

The J.R Peters 52024 Jack's Classic fertilizer is one of the best, well-balanced, all-purpose fertilizers you can buy today. It contains all three essential macronutrients in equal proportions (20 - 20 - 20). The evenly balanced formula means it greatly enhances roots, stem, and leaves development without any downsides.

With this fertilizer, you do not have to worry about overfertilizing your plants provided you follow the provided instructions on how to use this product. All you need is to mix a pinch of Jack's Classic fertilizer with a gallon of water and you are good to go.

NOTE: The instructions on the product's label might differ from what we wrote above but better safe than sorry! You can always research more about the effect of this fertilizer on the particular plants you want to apply it to.

Highlighted Features

  • Comes with detailed instructions on how to use it. The brand even includes a measuring spoon so you can make precise and accurate measurements.
  • Ideal for vegetables, trees, flowering plants, etc.
  • Comes with an evenly balanced macronutrient formula for optimal root, stem, and leaf growth.


  • It is not appropriate for use in Winter. In case you need to apply fertilizers to your plant during this season, you might want to check out other fertilizers.
  • It is not an organic fertilizer but it does promote the growth of blooming plants.

9. Espoma Organic Liquid Indoor Plant Food - Link

Espoma Indoor! Liquid Plant Food, Natural & Organic Houseplant Food, 8 fl oz, Pack of 1
Espoma Indoor! Liquid Plant Food, Natural & Organic Houseplant Food, 8 fl oz, Pack of 1

Espoma is another brand that excels at making fertilizers that you can confidently use, knowing they won't harm your plants. Of all the different Espoma fertilizers on the market, the recipe of this particular product made it impossible to ignore, hence, why we have it on our list.

As the name implies, it is best for anyone looking to start organic gardening.

NOTE: It is only suitable for indoor plants as the product name rightly points out.

It is easy to use; all you have to do is mix the product with water. There are no smells and you don't need any elaborate measuring techniques when diluting with water. About two to three drops of the liquid are enough for a gallon of water.

NOTE: Shake well before each use.

The biggest turnoff we noticed with this product is that the bottle is quite small for the price. The lingering smell after each use is also quite overpowering especially since it takes a few days to go away and you need to apply the fertilizer every 2 to 4 weeks.

Highlighted Features

  • Suitable for all houseplants such as cactus, vines, etc.
  • Easy to use
  • A remarkable difference can be observed within hours of applying this fertilizer.
  • Can revitalize plants struggling with proper light exposure.
  • The stopper automatically measures each dosage so all you have to do is shake the bottle and open it.


  • An incredibly bad smell lingers after a few days of use but the beneficial effects of these fertilizers are too great to overlook.

NOTE: Overall, avoid getting the fertilizer on your hands because of this lingering smell.

10. Jobe's Organics 09524 All Purpose Granular Fertilizer - Link

Jobe's Organics 09524 Purpose Granular Fertilizer, 16 lb
Jobe's Organics 09524 Purpose Granular Fertilizer, 16 lb

Yet another organic fertilizer from the Jobe's Brand. This time, we are considering this highly efficient granular fertilizer.

What we love most about this granular fertilizer is that it comes in different formulas. There is an All-purpose formula, a formula unique only for flowers and roses, a formula for annual and perennial plants, a formula for tomato and vegetable crops, etc. This gives you a wide range of options to choose from to ensure you get the best possible results when you use the fertilizer on your plant. For instance, it would only be right if you get a formula suitable for herbs if you are trying to use the product on your potted herbs. Using a formula uniquely designed for flowers and roses would more than likely harm plant growth. Of course, to be on the safer side, you can always buy the all-purpose formula so you don't have to worry about anything.

The product comes in three sizes; 1.5 lbs., 4 lbs., and 16 lbs. The fertilizer is certified by the USDA as ideal for organic gardening.

The product also contains Jobe's proprietary Biozome and Biozomethe. The biozome helps improves soil quality and condition in the long term while the boizomethe provides essential microorganisms to the soil that stimulates quick response of the plants to the nutrients being released to the roots from the granules.

Highlighted Features

  • Contains only organic ingredients which makes it safe for the environment
  • Contains a perfect blend of microorganisms which helps improve soil condition in the long term as well as nutrient absorption of the roots
  • Stimulates enhanced root growth which in turn improves plant growth and health
  • The granules are pets and kids friendly.


  • Comes with a bit of fishy smell
  • The fertilizer can sometimes attract bugs depending on the type of plant you use it with.

Best Indoor Plant Fertilizer Buying Guide

With all that has been discussed about the best fertilizers on the market right now, we also have some critical things you need to consider before buying just any Fertilizer. That way, your indoor plants get the best nutrients important for their growth and you also get the best value for your money.

1. Types of Indoor Plant Fertilizers

This is the main thing you need to consider before buying fertilizer. There are different types of indoor fertilizers. But how do you identify their uses and importance? Well, we got you covered!

  • Liquid Fertilizers

This type of fertilizer is only used whenever you want to irrigate the soil. Regardless of the formula in the fertilizer, Liquid fertilizers are only used once or twice each month.

They are only great for use during the dry season when there is less moisture in the atmosphere because of the hot weather.

  • Granular Fertilizer

As the name implies, they are in form of granules and are very efficient for young plants. However, because they are granules, they are not automatically absorbed into the soil after applying them. So, finding the right balance is very important.

It is highly recommended that you discard any instructions on the box of your fertilizer as the instructions might sometimes not be suitable for the plant you are trying to grow.

  • Slow-Release Fertilizers

This type of fertilizer comes in many varieties. They function in a unique way that makes them a long-term nutrient source for your plants and the soil.

Slow Release Fertilizers are often in pellets and spikes form. Some seeds are treated with essential chemicals that make them sprout quickly and grow efficiently with even nutrient distribution.

Although it is a long-term nutrient source for plants, this is also its biggest drawback. One can't tell how fast the nutrients will be dispersed into the soil or absorbed by the plant roots. T

2. Type of plant you want to cultivate

As simple as this sounds, it still bears considering. Different types of plants require different nutrients from the soil. As if that is not enough, they also have different life spans which essentially means they require different amounts of nutrients in the long run.

3. Price

This is only right to consider since without having the exact amount an item costs, you just won't be able to buy it. Fertilizer costs money to buy and comes at different prices. There are different reasons for this. For one, each fertilizer has a different formula - that is, they contain all the essential elements they supply to the soil and plants in different percentages. In addition, different brands of fertilizers also influences the price of a specific fertilizer.


How frequent should I use my indoor fertilizer?

This is very tricky to answer since there are different types of fertilizers, each with its unique formula and nutrient constituent. As a result, how often you apply any fertilizer depends on the type or brand of fertilizer you are using.

However, there is a consensus when it comes to applying fertilizers. Generally, fertilizers are often applied once every 2 to 3 weeks. Some powerful fertilizers are also applied once every 3 to 4 months.

NOTE: While doing some guesswork while applying a specific type of fertilizer is understandable, you don't necessarily have to guess! Most of the popular indoor fertilizers come with instructions that informs users on how to use the fertilizer.

When is the optimal time to use indoor fertilizers in the spring?

Contrary to what one might think, there are optimal times to apply fertilizers. There is also the right amount of fertilizer to apply depending on the plant. You don't want to overfeed your plant with fertilizer.

Spring is quite tricky to plant in. The right time to apply fertilizer on your indoor plants is usually about 8 weeks before spring or summer starts - that is after the first freeze.

That said, it is understandable if you are still confused. To help, we have compiled a few general tips you should know when applying fertilizers in general:

  • Most indoor plants are semi-dormant during winter. A fair few are even completely dormant as soon winter starts. The implication of this is that they do not require much nutrients when in this state. Using fertilizers on such plants during the winter often leads to retarded growth which could render them susceptible to insect infestation.
  • For indoor plants that shows significant growth during winter, it is okay to fertilize them. However, it is best to only use half or a quarter of the amount you would use if you were fertilizing the plant in summer.
  • For plants that flowers or bloom in the winter, you can apply fertilizer the normal way you would apply fertilizer during summer or spring.
  • If a plant is not growing as you want or expect, it is not reason enough to apply more fertilizer. Overfertilizing a plant does more harm than good because it corrupts the soil surface. In case you do notice stunted growth in a plant, ensuring the plant receive more light and water would better serve you than applying more fertilizer.
  • In situations where the plant you want to fertilize is purchased from a greenhouse, you should find out the last time the plant was fertilized. This can help prevent overfertilization.

How to Fertilize Indoor Plants?

How you apply fertilizer greatly depends on the form the fertilizer you want to apply is in. That is, how you would apply liquid fertilizer is different from how you will apply granular fertilizer.

Most of the best liquid fertilizers on the market come with instructions on how to use them. Although, to be quite honest, they generally come with the same, almost generic, instructions - which is always to add a tablespoonful of the liquid directly to the soil surface or into water that you will then apply using a spray bottle.

Granular Fertilizers on the other hand are applied onto soil surface. After which you have to water the plant to increase the rate at which the granular fertilizer releases nutrients into the soil.

NOTE: This is just a summary of how indoor fertilizers are applied. The best way to apply fertilizer is to follow any instructions the manufacturer of the fertilizer adds to their product or to follow other user's review of the fertilizer.

How will I know if my Plants needs fertilizing?

There are different ways you can identify when you need to fertilize your plants.

The most obvious way is by checking the growth of the plant. If the growth is stunted, then there is a big chance it lacks one of the essential elements needed to grow properly. In this case, you need to apply fertilizer.

NOTE: There is an exception you should take note. If the plant stills shows stunted or poor growth after the application of fertilizer, the answer is not to apply more. Instead, you should try to expose the plant to more sunlight or water.

Other signs you can use to identify when your plants needs fertilizer includes:

  • Leaf margins and tips showing yellow-ish or brown coloration;
  • Wilting of leaves or stems;
  • Unusual leaf drops; etc.

Are there natural ways to fertilize indoor plants?

Of course, there are. The easiest way to do this is making use of organic fertilizers. This type of fertilizer is made using organic materials. Asides from that, there are also certain ways you can add nutrients to the soil your indoor plant is growing in. For instance, you can add banana peels, coffee grounds, and gelatin power to the soil. Corn gluten meal also works provided it is fresh.


Indoor fertilizers are as important as sunlight and water which plants depend on. Finding one that is good, easy to use and compatible with the plant you are cultivating is not an easy task. This is made even more difficult because of the different reputations some of the brands producing these fertilizers have.

So how do you make a good decision overall? Well, we certainly hope our buying guide has done justice to that question.

However, for a brief overview of the buying guide, all you have to worry about is the plants you want to work with. Each plants requires different elements and nutrients from the soil in varying degrees and percentage. Hence, spend quality time to research about the plant before buying a fertilizer

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