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Plants growing in hydroponic systems do not get enough nutrients only from the water. For this reason, it’s necessary to apply fertilizer to your hydroponic system. 

What is the best fertilizer for hydroponics? To make the right choice, you must first understand which primary and secondary nutrients your hydroponic plant will need. Generally speaking, between 1-1-1 and 15-15-20 is an ideal NPK for hydroponic fertilizer. But, some plants require a higher or lower NPK, so be sure to do your homework!

Read on below to learn all about fertilizers for hydroponics to help you choose the right one for your plants!

How to Choose the Right Fertilizer for Hydroponics

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Photo by Anna Tarazevich on

Typically the use of the right fertilizer will help your plants grow strong and healthy, in hydroponics, it is absolutely necessary because plants rely on liquid nutrients rather than leaching them from the soil.

Before you jump to any conclusions about fertilizers for hydroponics, or which is the right one for you, ask yourself the following five questions:

1. Which Nutrients Must Fertilizer for Hydroponics include?

The fertilizer for your hydroponic systems must include primary and secondary nutrients. The primary nutrients include potassium, nitrogen, and phosphorus (NPK).

There is a wide variety of secondary nutrients, the main ones being calcium, magnesium, and iron, among others.

2. Which Level of N-P-K is Better for Hydroponics?

The best hydroponic NPK ranges from 1-1-1 to 15-15-20.

Nitrogen is a primary nutrient that speeds up the growth of plants. The numbers of NPK ratio that appear on the fertilizer indicates the percentage of each nutrient that the solution contains.

In the early stages of growth, plants need more nitrogen for foliage production. When plants start to produce flowers or fruits, a higher concentration of phosphorus is recommended. 

3. Organic vs Syntetic Fetilizer 

Organic fertilizers are in general a better option. However, this kind often has small particles that can clog the tubes of your hydroponic system.

Synthetic fertilizers have the same amount of nutrients as organic ones. The difference between them is that with synthetic fertilizers, the nutrients are pre-broken down, which makes their release faster than with organics.

4. How do you Use Fertilizers in Hydroponic Systems?

Every time you change the water of your hydroponic system, you can add a water-soluble fertilizer.

You’ll have to do it if half of the water of the system has evaporated or every four to six weeks.

5.  How Much Fertilizer Do I Need to Add?

Getting the wrong amount of fertilizer will impact the result. Depending on the size of your reservoir it’ll be the amount of fertilizer you need to add, per 16 gallons of water, the right amount will be between 1 to 2 cups of pre-mixed liquid nutrient solution.

Best Fertilizer/Liquid Nutrients for Hydroponics

There is no one-size-fits-all solution for hydroponics. That said, the following three liquid nutrients/fertilizers typically do the trick for most hydroponic crops.

Again, double-check the proper NPK for the specific types of hydroponic plants you want to grow first before choosing/buying one.

General Hydroponics FloraGro

The first item on our list is the General Hydroponics FloraGro liquid nutrients. This fertilizer product has a 2-1-6 NPK, which is great for all-purpose hydroponic crop growing. For certain crops, you may need to add pH adjusters to get the NPK just right but FloraGro will help get you there and keep your system stable.

Best for: structural repair and foliar growth of hydroponic plants, in general.

AeroGarden Liquid Nutrients

The second brand name hydroponic fertilizer product on our list is AeroGarden Liquid Nutrients. A 4-3-6 NPK, these liquid nutrients pack a little more punch than the General Hydroponics FloraGro (which may or may not be necessary for your hydroponic plants). For crops that are greedy for micro nutrients, AeroGarden liquid nutrients are recommended.

Best for: crops that have a high-demand for micronutrients in addition to basic NPK needs.

Fox Farm Hydroponics Formula

Last but far from least is the legendary Fox Farm Hydroponics Formula. These three products have various NPK levels that are just right for all the different types of crops you may want to grow including flowers, veggies, fruits, herbs, and houseplants.

Best for: the widest range of hydroponic gardening crops.

Related Questions

Can I use Regular Fertilizers in Hydroponic Systems?

It is possible to use regular fertilizer in hydroponic systems. You’ll have to check that the amount of Nitrogen it contains is Nitrate. Most soil fertilizers have Nitrogen as Urea which is not recommendable for hydroponic systems. You’ll also need to make sure it’s fully water-soluble. 

For How Long Do I Need to Use Fertilizer?

Keep in mind that the plants in your hydroponic system will not get enough nutrients from the water. For that reason, once you’ve decided on a nutritional plan, you’ll have to keep it consistent. Your budget is an important factor in deciding the kind of fertilizer you’ll use. 

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