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Indoor Plant Fertilizer: Making The Right Choices

Indoor Plant Fertlilizer

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When it comes to choosing the best indoor plant fertilizer for your plants, you need to understand the type of nutrients they require, and different indoor plants can require different levels of each major nutrient.

Sound complicated?

Well, when you first start out on your indoor plant gardening journey, it can seem a bit confusing.

But, when you do take the time to figure out what’s best for your plants, be that sunlight, potting mix, watering or in this case feeding, you’ll be rewarded with lush plants and produce.

So, learning to correctly fertilize your plants is essential- just as plants need water and sunlight to thrive, they need certain nutrients too. So, if we fail to provide them, their health will deteriorate.

To make sure your plants look their best and stay healthy from the inside out, here are the things you should know about plant nutrients and indoor plant fertilizer.

Plant Nutrients Simply Explained

There are three major plant nutrients, Nitrogen(N), Phosphorus (P) and Potassium (or potash) (K)

Different fertilizers have different ratios of these essential nutrients. The ratios are always listed in the same order, ie N-P-K.

Balanced fertilizers commonly used for a wide range of indoor plants have equal parts of all three nutrients, a popular example being 20:20:20

Nitrogen is known as the foliage maker as it promotes strong healthy leaves.

Phosphorus is referred to as the root maker, with strong, healthy roots being essential for the absorption of nutrients required for plant growth and happiness.

Potassium or potash, is the flower or fruit maker and is often added to plants a few months before they are due to bloom or bear fruit.

Plants take up fertilizer in solution through their roots, meaning if the potting mix is dry, not only will the plant dehydrate, it will not be able to absorb fertililzer through its roots.

Most indoor plants only require feeding during their growth period which is usually between spring and autumn.

It’s generally recommended that you stop feeding your plants during the non growing, colder months of winter.

A final note to remember on nutrients is that different plants require different nutrients at different dosage levels.

You can refer to the plant article of your choice at for plant specific fertilizer requirements.

Also remember that overfeeding indoor plants can be as bad, if not worse, than underfeeding them.

What are the main types of indoor plant fertilizers ?

  • Organic

Organic fertilizers are made of natural materials. The most common are manure, compost or other products from plants and animals.

They’re a popular choice thanks to their abundance in nutrients; however, the amount is always an approximate.

They work gradually and long-term. And, this type of feeding is a good option if you want to enrich your garden soil over time.

The best thing about organic fertilizer is that you can make it on your own from things in your garden.

  • Non-organic

These manmade fertilizers are based on chemicals with specific nutrients.

They’re an awesome pick if you’re looking to give your plants a quick boost.

You can find them in several forms, depending on how they affect the plants and what you want to achieve.


  • Liquid Fertilizer for Indoor Plants-if you want to supply your plants with a quick fix, this is a great option. Liquid indoor plant fertilizers dissolve in water and can be found in concentrate or dry form.

The roots and the foliage absorb them right away, which is ideal for treating plant deficiencies or some other deficiency-caused issue.

But, more care is necessary with this fertilizer; if you don’t apply the proper dosage, you can damage the plants. In fact, excessive amounts can burn the foliage, cause discoloration, and even harm the roots. It’s best to begin by diluting the liquid fertilizer concentrate to 50% of the recommended dosage.

  • Slow-release Fertilizer –this fertilizer is granular and it’s not immediately soluble in water. They release the nutrients into the soil gradually, not right away like the liquid fertilizers do.

Use a slow release fertilizer to prevent root and foliage burn and prolong the plants’ longevity. However, as they take longer to do their job, the plant may not get the needed nutrients and recover fast enough if seriously deficient. 

As with the liquid fertilizers, you need to be careful with the dosing-too much can burn the foliage!

  • Fertilizer Spikes

Fertilizer spikes (or sticks) are a popular form of slow release fertilizing.

You gently place the fertilizer spike into the plant soil about half way between the plant and the edge of the pot.

The number of spikes you’ll need per pot can be calculated by dividing the width of your pot by two, for example a six inch wide pot will require 3 spikes and an eight inch pot will require four.

  • Specialty Fertilizers

To make it easier for indoor gardeners, many manufacturers of indoor plant fertilizers produce specialty fertlizers that meet the specific needs of specific plant types such as succulent fertilizers, orchid fertlizers and so on. These speciality fertlizers can take all the stress out of deciding what nutrients are required for your plants in what ratios.

Which indoor plant fertilizer to choose for my plants?

  • Houseplants & other plants in containers

Although some indoor plants may need more fertilizer and others less, generally, sticking to a balanced houseplant fertilizer schedule is good practice (cactuses love liquid and diluted fertilizer, ferns do well with a slow-release fertilizer, lighter fertilizer, etc.)

  • Flowers

Indoor flowers will do well if you feed them according to the same regiment you use for your other houseplants.

If you have them in your outdoor garden, do it as you would feed landscape flowers (winter or early spring, before growing season, using a slow-release fertilizer).

  • Veggies

Some veggies like the cold weather ones (radishes and lettuce) and prefer a fast-release fertilizer as it’s best for cooler soil.

On the other hand, for warm weather veggies like tomatoes and corn, choose a slow-release fertilizer.

How to fertilize indoor plants the right way; do’s & don’ts


  • Fertilize the plants in direct sunlight more than those in shade
  • Choose a slow-release fertilizer when possible to prevent burning, weakened immunity, pests, and diseases
  • Do it according to the manufacturer’s instruction-otherwise, you could damage your plants
  • Feed plants that are deficient in nutrients with a fertilizer that has a more immediate effect, such as a liquid one
  • Consider fertilizer spikes; when you’re unsure when and how much to give to your plants and produce, fertilizer spikes can help; this gradual release fertilizer works underground and it’s measured in advance

It will lower the risk of overfeeding your indoor plants and shrubs or trees outdoor.


  • Overfeed your plants-this can cause foliage damage and even weaken the roots
  • Spray the plant with it- fertilizer should always go directly into the soil!
  • Water the plant after fertilizing- it’s best to do it before; this will lower the risk of burning the plants
  • Never spill it into the sewerage system-it can harm the public water supply!

How to prevent overfeeding your plants

When you’re not sure about the amount of fertilizer your plants need, under-feeding is always better than overdoing it.

Overfeeding causes problems like brown or yellow foliage and increase the risk of root damage. To prevent this, always:

  • Dilute the liquid fertilizer to half the strength on the label
  • Feed the leafy and flowering houseplants according to the time of year (growing season more, dormant season less)
  • Recognize the heavy feeders like veggies, roses, and fruits (they like to be fed once per month when actively growing with an all-purpose fertilizer)
  • Recognize the light feeders such as trees and shrubs; these perennials don’t need a lot of fertilizer; once in spring will be enough

How to detect an underfed plant

A plant that’s lacking in vital nutrients will often display some of the following tell tale symptoms;

  • Pale leaves
  • Yellow foliage
  • Poor growth
  • A lack of flowers

I do hope you’ve found this indoor plant fertilizer article helpful and that you apply these tips for a beautiful, healthy indoor garden.

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Fertilizer Spikes

Christine Mattner

What started out as purely a desire to keep my indoor plants alive has turned into a full-blown passion for sharing what I have learned over the years about selecting, growing and caring for indoor plants with those who may be new to the wonderful world of houseplants.

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