5 Best Indoor Plant Fertilizers

Naturally, plants make their food through photosynthesis, but it doesn’t hurt to give them a little fertilizer and enhance that process. Fertilizer acts like a multivitamin for plants supplementing what they get from the sun and the soil for optimal growth.

Now, there are various fertilizers, each suited for a specific type of plant or condition. That said, what works for outdoor plants may not be ideal for indoor plants and vice versa. The nutrients needed for both types vary, and so do the fertilizers [1].

If you are looking for the best indoor plant fertilizers, this article reviews some of the best on the market. You also get to understand how to choose a favorable one by considering a few essential factors.

Top Indoor Plant Fertilizers

Best Overall Fertilizer

1. Miracle-Gro Indoor Plant Food Spikes

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

Miracle-Gro is known as one of the best brands when it comes to indoor plant fertilizers. This particular one is formulated for all indoor plants and comes in the form of spikes for easy use. It is, therefore, an excellent starter fertilizer if you are new to the world of fertilizers.

Key Features:
  • Easy to use
  • Lats up to 2 months
  • Safe on all indoor plants
  • Packed with micronutrients

Finding a fertilizer that is easy to use and one that is beneficial to your indoor plants can be quite a challenge. Luckily Miracle-Gro has formulated one of the best fertilizers to meet the nutrient needs of most indoor plants supporting growth and development.

The fertilizer is super easy to use and only requires you to make a hole in moist soil using the spike. Then push the spike down halfway between the plant stem and the pot rim. You can make several holes depending on the size of your plant.

Press down the spikes until covered by soil to ensure the fertilizer reaches down the pot. For best results, replace spikes every thirty days, especially in the spring and summer. During the fall and winter, replace the spikes every 60 days and water the plants as required.

Pros

  • Suitable for most indoor plants
  • Easy to spike and use
  • A little goes a long way
  • Provides the right balance of nutrients

Cons

  • It can be challenging to monitor the doses risking overdosing, especially with smaller plants.

Best Organic Fertilizer

2. Earthpods Premium Concentrated Indoor Plant Food

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)

In a world where we have organic and non-organic versions of everything, finding organic options has proven a challenge, especially with plant fertilizers. T

The good thing is that brands such as EarthPods have organic formulas to provide the proper nutrients in an eco-friendly formulation. Here is one of their amazing fertilizers you can try for your indoor plants.

Key Features:
  • Concentrated premium all-purpose formula
  • Pre-measured plant fertilizer
  • Easy to apply
  • Slow-release fertilizer
  • Eco Friendly
  • Compact design

The formula this fertilizer comes with makes it one of the best for struggling indoor plants. It is formulated to support root growth, promote strong stem development, and enhance leaf growth contributing to the overall health of your indoor plants.

It is easy to use and eliminates all the mess associated with most other plant fertilizers. On this note, the fertilizer does not have a funky pungent smell, therefore friendly to use indoors. And, it is pre-measured, so you do not have to worry about scooping to measure.

You only need to push one EarthPod down to the root system, ensuring it gets to the center of the plant. Then with regular watering, the fertilizer will slowly release the nutrients, boosting the soil’s quality and ultimately the health of your plants.

Pros

  • Friendly to the environment
  • Easy to apply and sustain
  • Rich formula for all indoor plants
  • Messy-free, no-smell formula
  • Compact for easy storage

Cons

  • You may need a lot of pods to provide enough fertilizer for larger pots which can be expensive in the long run.

Best Liquid Fertilizer

3. Miracle-Gro Indoor Plant Liquid Plant Food

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

Another option from Miracle-Gro, this liquid fertilizer is an easy pick for occasional use. The liquid fertilizer comes in handy to mix in with the soil or water to provide the nutrients for your plants.

Key Features:
  • For all indoor plants
  • Instant nourishment
  • One-a-week formula
  • Handy application bottle

Most growers agree that liquid fertilizers are some of the best on the market. This has to do with how easy they are to use compared to the fantastic benefits they bring to the plants. And the flexibility of not having to apply them continuously.

That said, this liquid gold from Miracle-Gro is an ideal choice for nourishing your indoor plants and boosting their growth and development. A little goes a long way since you only need to apply the fertilizer once a week, therefore an economical option.

If you use it directly to the soil, apply one pump for small pots and two pumps for larger pots. Water the plants as required to drive the fertilizer down to the roots. If you choose to mix in water, use four pumps in a regular watering can and water as usual.

Pros

  • High-quality rich formula
  • Easy to use
  • Economical fertilizer
  • Works well for edible plants

Cons

  • The pump on the bottle can be a little flimsy.

Best Water-Soluble Fertilizer

4. Miracle-Gro Water Soluble Plant Food

Miracle-Gro has built a name thanks to their unique formulas, and this particular one is no exemption. This is one of the best water-soluble fertilizers on the market, owing to the fantastic feedback that other growers have left about it.

Key Features:
  • For use every 1-2 weeks
  • Easy to use
  • For all indoor and outdoor plants
  • Simple to dissolve

The trick with this fertilizer is to ensure you use it as directed to get the most benefits out of it. The good thing is that it is easy to use, so you do not have to worry about getting the right amounts for specific plants.

You can use this fertilizer with the Miracle-Gro feeder, which is convenient and practical for beginners. You just need to fill the jar with one of the water-soluble plant foods. Then attach the garden hose and turn on the water. Lastly, choose a favorable sprayer and soak the base of the plant.

Another way to use it is by mixing the fertilizer in your watering can. Mix one tablespoon of the plant food for every gallon of water. Fill the watering can with clean water and dissolve the fertilizer. Water your plants, as usual, soaking the base of the plant.

Pros

  • Provides excellent results with consistent use
  • Works well with most indoor and outdoor plants
  • Dissolves quickly
  • Easy to apply

Cons

  • Pricey

Best Smart-Release Fertilizer

5. Osmocote Smart Release Plant Food

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

When looking for fertilizer, one of the things you should look for is the number of nutrients. While those with the most nutrients do not necessarily indicate their value, having a few more in the formula could benefit your plants.

This smart-release Osmocote fertilizer is a great buy, a top-rated product by thousands of growers.

Key Features:
  • 11 essential nutrients
  • For all plant varieties
  • Works with potted plants
  • No-burn formula
  • It lasts up to 6 months

The smart release aspect makes this fertilizer an interesting one to try. The fertilizer consists of a nutrient granule coated with semi-permeable resin. The coating allows water to penetrate the granule and dissolves the nutrients inside.

After dissolving, the nutrients are released as the temperature changes. Generally, more nutrients are released during warmer periods when the plants are actively growing. After release, the empty capsule remains and does not need to be removed.

This system is ideal if you are looking for a fertilizer you do not want to apply regularly. It can last up to 6 months without the need for replacing; therefore convenient and economical too.

Pros

  • Works well with flowering plants
  • Easy to apply
  • A little goes a long way
  • High-quality nutrients

Cons

  • The capsules come in plastic material.

Factors to Consider When Looking For an Indoor Plant Fertilizer

As a beginner in indoor gardening, finding the right fertilizer for your plants can be challenging. This guide below can come in handy to help you figure out what your plants need and the most appropriate option to support their growth and overall health.

Type of Fertilizer

Fertilizers come in different types, with each suiting a specific set of conditions.

Liquid Fertilizers

Liquid fertilizers are the most common type used by many gardeners, thanks to their easy application. All you need to do is dissolve in water and water the plant as required.

The advantage of using liquid fertilizers is that they reduce the risk of over-fertilizing since you control how much product you use. That means you can limit or increase the amount of fertilizer depending on the plant.

Granular Fertilizers

This type of fertilizer is mixed in potting soil and is commonly used for outdoor plants. Some of these are suitable for indoor plants, too, as long as you understand the kind of nutrients your plants need.

They seem to work well; however, you do not have much control over the product since you can never know how much fertilizer to add [2]. But, these fertilizers are cheaper and pretty easy to use.

Slow-Release Fertilizers

This type works well for both indoor and outdoor plants and has minimum risk of fertilizer burns. The nutrients are packed in a shell that releases them slowly with temperature changes. Some last as short as three months, while others can last as long as six months.

They are easy to use, and you get control over the product; however, they can be expensive and may dent your pockets if you need them in bulk. All the same, they are worth the investment with the fantastic benefits they bring.

NPK Ratio

Another essential factor to consider is the NPK ratio, which is the ratio of the three major nutrients that plants need. These are nitrogen, phosphorus, and potassium. These three are equally crucial to house plants as they are to outdoor plants [3].

Nitrogen

Nitrogen is responsible for leaf growth and development in addition to promoting color for indoor plants. A limited supply of nitrogen results in pale, floppy plants accompanied by slow growth.

On the other hand, too much nitrogen is not ideal for fruit-bearing and flowering plants as it will impact growth negatively. This will result in a lower yield of flowers and fruits. Therefore, nitrogen should be balanced to benefit the plant.

A significant role of nitrogen is promoting chlorophyll production, which is essential for processing food via photosynthesis. Generally, it is responsible for the overall growth structure of your plants [4].

Phosphorous

Phosphorous is essential for the development of fruit, flower, seeds, and roots; therefore an important nutrient for the overall health of your plants. It enhance flower and seed production, directly impacting the yield.

It also helps plants absorb other essential nutrients contributing to a strong root system. If the supply of phosphorous is limited, plants develop slowly and show little or no signs of blooming.

Potassium

Pottasium is essential for root and stem development helping your plants build a strong structure from the beginning. It supports photosynthesis and activates enzymes contributing to the overall health of your plants.

A deficiency in potassium manifests as lower yellowing leaves that later wilt and fall. This slows down the overall growth of the plant and, if not fixed, results in the death of the plant. Therefore, ensure the fertilizer you choose phosphorous as a major nutrient.

The Bottom Line

Fertilizers are useful in replenishing lost nutrients, making sure your plants have a steady supply of food to support growth and development. If you are looking for ideal fertilizers for your indoor plants, these above are great options to support the health of your plants.

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