Best Aquarium Plant Fertilizer

Live aquatic plants are a fantastic addition to any aquarium. Not only will they look beautiful as they move naturally against the current generated by your filter, but they’ll oxygenate the water in your aquarium too. 

This means healthier fish, better-quality water, and less time cleaning in between water changes. Aquatic plants also offer your fish and other aquarium residents a naturalistic, safe space to hide in when they sense a threat. 

However, one thing that many fish owners tend to forget is that aquatic plants need food to survive and maintain their role in your aquarium’s ecosystem. But just how do you go about feeding an aquatic plant?

Best Aquarium Plant Fertilizer

The answer lies with aquarium plant fertilizer. Loaded with all of the minerals and nutrients your aquatic plants would ordinarily feed on in their natural habitat, aquarium plant fertilizer will help ensure they are strong, healthy, and disease resistant. 

Finding the perfect fertilizer for your aquatic plants can be difficult though, and you certainly can’t use a basic fertilizer you’d normally apply to your garden or house plants. But don’t worry - we’re here to help! 

Below, you’ll find our list of the best aquatic plant fertilizers available. Each of these is ideal for feeding your aquatic plants and maintaining the health of your aquarium. We’ve also put together a useful buying guide that will help guide you towards the perfect aquarium plant fertilizer for your individual needs. 

In a hurry? Let’s begin by taking a look at our top pick. 

OUR TOP PICK

Packed full of phytohormones, minerals, and nutrients, Flourish Freshwater Plant Supplement from Seachem is perfect for giving your aquarium plants everything they need to grow strong and healthy. 

It does this by stimulating root growth beneath the surface of your aquarium’s substrate. This then leads to a significant improvement in leaf and stem health. By feeding your plants directly from the root, it also helps to ensure that they remain disease resistant and increases the plant’s ability to absorb minerals.

The completely non-toxic formula makes it safe to use in all aquariums and it won’t cause any harm to fish, plants, or any other living organisms in your tank. This freshwater plant supplement will also last you a long time too as you only need to use 5ml (one capful) per 80L of water. This gives you extra value for your money.

Pros

  • Contains all the phytohormones, minerals, and nutrients aquatic plants need to grow strong and healthy
  • Feeds plants directly at the root which stimulates root growth and improves leaf and stem health
  • Helps to enhance mineral absorption and disease resistance 
  • The non-toxic formula is safe to use with all aquatic plants and fish
  • Lasts a long time, with only one capful being needed per 80L of water

Cons

  • Can take between 10 - 14 days for the benefits to start visibly showing

EDITORS CHOICE

If you’ve started noticing the leaves on your aquatic plants turning yellow, this Leaf Zone Aquarium Plant Treatment from API could be the solution to your problem. Containing chelated iron, potassium, and a wealth of other minerals essential to plant health, it works hard to ensure your plants can photosynthesis and grow healthily.

These minerals also work together to maintain the correct level of cell pressure in the plant’s leaves. This allows them to generate lush, new growth and ensures that the leaves are vibrant all year round. 

This plant treatment is absorbed directly through the leaves of your plants too, which makes applying it much easier as you can simply pour it into your aquarium’s existing water. You’ll get a lot of use from one bottle too, as you only need to use 5ml for every 10 gallons of water. There are even measurement marks inside the bottle cap to help make dosage even easier.

Pros

  • Contains a wealth of minerals essential for plant health including chelated iron and potassium
  • Helps to prevent leaf yellowing and encourages strong photosynthesis 
  • Also helps to maintain the correct cell pressure level so healthy, new growth and form
  • Easy to apply and is absorbed directly through the plant’s leaves 
  • Only 5ml of treatment is needed for every 10 gallons of water, and there are measuring marks on the cap to help with correct dosage

Cons

  • You need to get the dosage correct, otherwise, algae growth could be stimulated 

BEST VALUE

One of the things that make these NilocG Aquatic Thrive Caps stand out from the crowd is that, unlike most aquarium plant fertilizer, they aren’t in liquid form. This means that there isn’t so much worry over getting the dosage correct and application is easier than ever.

Simply place one tablet per plant directly into your aquarium’s substrate at the bottom of each plant and it will act as a slow-release fertilizer. Once in position, it will provide a steady supply of nutrients and minerals that help your plants grow strong. This includes nitrogen and phosphate which are essential for plant health. 

They also include iron-rich clay and mineralized topsoil, which allows them to replicate the minerals aquatic plants would naturally feed on. They only need to be replaced every 3-4 months too, so they’re ideal if you’re after an aquarium plant fertilizer that’s fairly low maintenance. 

Pros

  • Fertilizer tablets that are easy to use and don’t require any dosage calculations
  • Designed to be placed directly at the base of each plant where they will act as a slow-release fertilizer
  • Packed with minerals including nitrogen, phosphate, iron-rich clay, and mineralized topsoil
  • Encourage healthy aquarium plant growth and strengthens disease resistance
  • Each tablet lasts for 3-4 months before it needs replacing

Cons

  • Need to be planted firmly into your aquarium’s substrate, otherwise, they could float to the surface

RUNNER UP

One of the nutrients you’ll find in this Aquarium Plant Food from Aqueon is kelp extract. This is fantastic for encouraging healthy root development which, in turn, ensures that the rest of the plant is strong. 

It’s also full of macronutrients and micronutrients that freshwater aquarium plants need to fight off any potential diseases and continue growing as healthily as possible. These include calcium, magnesium, and iron. 

This aquarium plant food is super easy to use and can simply be poured directly into your aquarium. Once in the water, it will find its way to the roots of your plants and get straight to work. It will last a long time too, with only 2ml of fertilizer needed for every 2.5 gallons of water. There are even measuring marks inside the bottle cap to help make sure you’re administering the correct dose. 

Pros

  • Contains kelp extract to encourage root development and promote strong plant growth
  • Also contains calcium, iron, and other macronutrients and micronutrients to keep your aquatic plants strong and healthy
  • Super easy to use and can be poured directly into your aquarium’s water
  • Lasts a long time, with only 2ml of fertilizer needed per 2.5 gallons of water
  • Includes measuring marks on the bottle cap for easy dosage calculation

Cons

  • The green/brown color of this fertilizer can add a temporary murkiness to the water. This clears within a couple of hours though.

RUNNER UP

If your aquarium contains quite a lot of fish but not very many live plants, this Premium Nutrition Fertilizer from Tropica could be the ideal choice. This is because it doesn’t contain any nitrogen or phosphorus, which occurs naturally in fish waste, so won’t it overload your plants and cause leaf-burns. 

Amongst the nutrients that it does contain, however, you’ll find manganese, iron, and other minerals that are vital for root development and healthy plant growth. These micronutrients also help to restore vibrancy to any discolored leaves and help to ensure they are lush and green at all times. 

This aquarium plant fertilizer couldn’t be easier to use either. There isn’t any need to measure out doses. Instead, simply use the included bottle-pump to administer the correct amount for your tank. Each pump dispenses 2ml of fertilizer each time, and the reference table on the back of the bottle tells you how many pumps are needed for your tank’s size. 

Pros

  • Doesn’t contain any phosphorus or nitrogen so is ideal for aquariums with a large number of fish but very few live plants
  • Contains manganese, iron, and other minerals that encourage strong growth and root development
  • Helps to restore vibrancy to discolored leaves and prevents further yellowing
  • Super easy to use with a bottle pump design and quick-reference dosage table
  • The concentrated formula won’t cause any murkiness in the water

Cons

  • Not designed for use with a larger collection of aquatic plants 

Best Aquarium Plant Fertilizer Buying Guide

Just like your fish need food, any live plants you’ve placed in your aquarium also need feeding from time to time. The best way to do this is by using an aquarium plant fertilizer. 

However, this isn’t as simple as purchasing the first one you find. It’s important to make sure that your chosen fertilizer is suitable for your aquatic plants, and that it won’t cause any harm to your fish, shrimp, or any of the other residents living in your aquarium. 

Below, we’ve highlighted some points to consider when you begin shopping for an aquarium plant fertilizer. These will help guide you towards the best choice for your needs and make sure you get the perfect fertilizer the first time around. 

Non-Toxic

Since you’ll be adding it to water that contains fish and other living creatures, the first, and potentially most important thing to look for is whether the plant fertilizer you’re choosing is non-toxic. 

It’s highly unlikely that you’ll come across a plant fertilizer that will cause any harm to the animals in your aquarium, but it’s definitely worth researching. In most cases, the toxicity will be stated on the bottle. If in doubt, however, get in touch with the brand’s sales team who will be able to give you more information. 

Minerals & Nutrients

There are certain minerals and nutrients that aquatic plants feed on in their natural habitat. These include magnesium, iron, and nitrogen, all of which play a certain role in maintaining plant health. So, with this in mind, it’s a good idea to look at what minerals and nutrients your chosen fertilizer contains. 

To help make this a little easier, we’ve listed some of the essential nutrients your aquarium plants need below. You’ll also find a brief description of what it is these minerals and nutrients do.

  • Nitrogen: Helps aquatic plants photosynthesis. This allows them to produce their own food and, in turn, oxygenates the water more efficiently.
  • Phosphorus: Helps to maintain steady plant growth. This doesn’t only mean your aquatic plants are kept healthy, but also restricts the rate at which algae grows. 
  • Potassium: Controls plant stomata (the cells that control water intake). Fertilizer that contains potassium allows the plant to use water more efficiently and strengthens disease resistance. 
  • Magnesium: Aids in the efficiency of photosynthesis. It also helps the plant produce more chlorophyll and this is what allows the leaves to maintain their vibrant, green color. 
  • Iron: In their natural habitat, aquatic plants draw on iron as a source of energy whilst they photosynthesis. Without any iron, photosynthesis is weaker and the plant becomes more likely to suffer from disease, stunted growth, and leaf discoloration.

These are just a few of the essential minerals to look out for when you’re shopping for an aquarium plant fertilizer. Some contain other nutrients in the mix, such as kelp extract, to help develop a healthy root system.

It’s worth noting, however, that both nitrogen and phosphorus occur naturally in fish waste. Too much of these two minerals can cause leaf-burning and discoloration so, if you’ve got a tank that has a lot of fish and a lot of live plants, look for a fertilizer that doesn’t contain any nitrogen or phosphorus. 

Application

You’ve got a couple of choices when it comes to the type of fertilizer you can use with aquatic plants, and the one you pick will have its own application method. 

The most commonly available fertilizer comes in liquid form. This is super easy to apply to your plants and, in most cases, can simply be added to the water where it will find its way to the roots and leaves. 

The second choice you have is fertilizer tablets. These are designed to be planted into your aquarium’s substrate alongside each plant and act as a slow-release fertilizer. Tablets are slightly more inconvenient to apply than a liquid fertilizer, but they last a long time and won’t need to be replaced for months at a time. 

Dosage

Depending on the type of fertilizer you’ve opted for, you’ll next need to figure out how much you need to use each time you apply it. Tablet fertilizer is a little easier to work out as in most cases you only need to place one tablet beside each individual plant. 

Things can start getting a little more complicated when it comes to liquid fertilizer. Luckily, there are certain guides in place to help you work the dosage out. 

Many liquid fertilizers come with bottle caps that are etched with measurement markings. This, when used alongside the fertilizer’s dosage reference table, allows you to easily work out how much fertilizer you need in comparison to the size of your aquarium.

Some brands have made life even easier, and come with bottle pumps that dispense a set amount of fertilizer each time. This means there’s no messing around with pouring fertilizer into caps. Instead, you simply pump the fertilizer directly into your aquarium the correct number of times. 

Looking at the dosage levels before purchasing will also give you a better indication of how long a single bottle of aquarium plant fertilizer will last. This gives you the opportunity to find a bottle that will last you a long time and gives you extra value for money. 

Frequently Asked Questions

What fertilizer is best for aquarium plants?

There are a few essential nutrients and minerals that all aquarium plants need to grow healthily. Any aquatic plant fertilizer that contains nitrogen, phosphorus, and potassium would be an ideal choice. You should also look for a fertilizer that contains iron and magnesium to give your aquatic plants their best chance of survival.