Hydroponic Nutrients Guide

If you’ve come from my post on Hydroponics for Beginners, welcome!

If you haven’t, welcome anyways!

This post is designed to give you an overview of hydroponic nutrients – what they’re made of, what they do, and the different types.

What are Hydroponic Nutrients?

Because we are growing plants without soil, we miss out on a good deal of nutrients that soil contains. When mixed with water, hydroponic nutrients are designed to replace all of the macro and micro nutrients found within soil. So, exactly what makes up a bottle of nutrients?

The first thing you’ll notice when you browse through bottles of nutrients are three numbers printed on the front of every bottle. This is known as the N-P-K ratio, or Nitrogen/Phosphorus/Potassium ratio.

The NPK ratio tells you exactly how much of each macro nutrient the bottle contains. If a bottle says 9-9-9, this means that the solution contains 9% Nitrogen, 9% Phosphorus, and 9% Potassium. You might have noticed that this adds up to 27% – what’s in the other 73%? Typically, water, micro nutrients and other chelating agents make up the rest of the solution.

The NPK ratio will differ depending on what phase of growth the plant is in – but we’ll get to that later. First, let’s talk about what these different macro nutrients do for a plant’s growth.

Macro Nutrients

Nitrogen, Phosphorus, Potassium. These three nutrients are absorbed in the largest quantities by plants and are known as macro nutrients. They serve absolutely vital roles in a plant’s development. Here’s what each of them do:

Nitrogen – Necessary for the formation of amino acids, co-enzymes, and chlorophyll.

Phosphorus – Sugar, phosphate and energy production. Helps to produce flowers and fruits, as well as stimulates root growth.

Potassium – High levels of this element are required for protein synthesis. Helps to manufacture sugars and starches, as well as contributes to root growth and plant hardiness.

Without these macro nutrients, a plant could not survive. Plants need different amounts of these macros in different stages of their lives. An excess or deficiency of any of these nutrients can be devastating to a plant’s development.

Micro Nutrients

Plants need more than the three macro nutrients to thrive. The following nine elements are known asmicro nutrients, and are required in smaller quantities for a healthy plant.

Boron – Combined with Calcium, helps to form cell walls.

Calcium – Combined with Boron, helps to form cell walls.

Copper – Activates enzymes and is required for respiration and photosynthesis.

Iron – Used to form chlorophyll and in respiration of sugars for energy.

Magnesium – Catalyzes the growth process and makes oxygen during photosynthesis.

Sulfur – Synthesizes protein, helps with fruiting, seeding and water uptake. Also acts as an organic fungicide.

Zinc – Helps to form chlorophyll, along with assisting respiration and nitrogen metabolism.

Types of Hydroponic Nutrients

Nutrients typically come in two different varieties – powdered and liquid. The powdered variety is generally harder to work with. It won’t dissolve fully into water and oftentimes doesn’t have added pH buffers. Liquid varieties are much more popular and easy to use. They come highly concentrated, so it’s important not to spill any on your body or your plants. Other than that, they’re fairly easy to use. All you need to do is mix them thoroughly into water at the desired concentration, and you’re set. Most of them come with pH buffers, which means that you don’t have to balance the pH of your water yourself – the nutrients do it for you.

Hydroponic Nutrients

General Hydroponic 3 Part

The picture to the right is an example of a very basic liquid nutrient package. The General Hydroponics Flora Series of nutrients is the most-used hydroponic nutrient package in the entire world. It contains FloraGro, FloraMicro, and FloraBloom nutrients. As your plants grow through their lifecycle, you need to provide them with different ratios of nutrients. This is where the GH Flora Series really shines, as it makes it very easy for you to customize your nutrient mix. I believe it sells for around 20 bucks as well, which makes it a super cheap way to get into growing plants hydroponically.

If you want to go with the GH Flora Series, I’d suggest picking up their pH buffer and testing kit. It will help you adjust the pH of your nutrient solution so that it’s absolutely perfect for your plants.

Get Started!

Hopefully this article has shined some light on the potentially confusing world of nutrients for hydroponic systems. While there are hundreds of different brands and varieties out there, it’s best to keep it simple as a beginner. For this reason, I recommend starting out with:

This is all you’re going to need to feed your plants a balanced mix of nutrients that will help them grow as optimally as possible!

Ready for more? Check out the next article in my Hydroponics From Scratch series – pH and Nutrient Availability!


Kevin is the creator of Epic Gardening, a community dedicated to teaching urban gardening, hydroponics, and aquaponics. He enjoys skateboarding, piano, guitar, business, and experimenting with all kinds of gardening techniques!

  • James Hicks

    How often do you need to change the water & add nutrients to the system? I’m a great gardener in soil & trying to learn more about hydro dardening so any tips that you could give me would be helpful. Thank You for your time.
    James Hicks

    • Hi there James – I usually will refill the system every week, but I am a fan of making it as easy as it can be, so I tend to just fill it back up to the normal level instead of changing the entire system out. If you’re noticing a serious pH imbalance or too high/low parts per million of your nutrient solution, you might need to do a full swap just to get everything back to normal levels.

      Just adding what is needed is a great way to conserve water instead of dumping out 10 gallons a week 🙂

      • Samizdat

        Yah I have a 55 gallon Rex and due to it large volume it easy to keep under control. I rarely switch out the whole thing, especially since I use RO water so it is timely and frankly wasteful. Just topping off the water and adding in some extra nutrients works great for me, about once a week I add some
        Nutes and a few gallons of water. Hasn’t done me wrong yet.

        If I had a smaller reservoir, I would change it out weekly since its harder to manage the appropriate levels when you only have 5 or 10 gallons of water to deal with. Adult tomatoes drink lots of water so it can be tough!

        • I really like the never drain strategy, wastes much less water and generally is more efficient. Only thing you have to deal with is exactly what you said – managing the water/nutrient ratio. I’ve only got 15-20gal reservoirs max, so this happens a lot to me. Water gets sucked up more than nutrients, PPM goes up and burn occurs so I’ve got to stay pretty vigilant when it comes to keeping my res in good shape.

  • Anthony

    Assuming we can’t get a hydroponics specific solution, will regular liquid solutions do?

    If so, what NPK contents are we looking for? The ones in the General Hydroponics look lower than any I’ve seen.

    • Hey Anthony,

      Regular liquid solutions are just fine and I actually use the General Hydroponics three part nutrient for most of my grows. Their line is a great – and cheap – way to get started growing. Their NPK values are low, but only because all three solutions (FloraGro, FloraMicro, FloraBloom) are used in unison to create the perfect nutrient blend for each phase of growing.

      Thanks for reading, and let me know if you have any other questions!

      • Anthony

        The blog is great, and has helped me a lot. Thanks a lot! I’ve started my own. When I get it going, I’ll share!

        • Thanks! Let me know when you do, I’d love to take a look. Also, let me know if there’s anything you’d like to see on the blog, I’m in the process of moving houses right now but once I’m settled in there’s going to be a lot more hydroponic tutorials, posts, etc!

          • Anthony

            Me to! I just moved in at the beginning of the month. I’m trying to get this project going while unpacking and writing my MSc thesis.

          • Anthony

            Hey Kevin. Here is my blog: http://howieslife.wordpress.com/.
            I’ve outlined a plan in today’s post. Hopefully you can share some insight into some of my problems.

  • Samizdat

    I personally use X Nutrients, which comes in a similar 3 stage setup of grow/bloom/micro-nutrients. Works great for me but is a bit pricey. I don’t recall the size of the container but I think it’s about $20 a gallon for each. That will last almost a whole grow cycle but the bloom one goes the quickest, since it’s mainly bloom nutrients that are needed once the tomatoes etc start flowering.

    • I’ll have to check out X Nutrients. GH is a great starter for total beginners, but I agree that you’re going to want to experiment with different combinations, micronutrient solutions, etc once you’ve got a bit more experience, which it sounds like you have!

  • abdu razack

    Thank u m. Kevin. for giving information about the hydropionic cultivation and pls let me know the best guide to do for tomato describe nutrition ratio and prevention of deseases

    • Kevin

      Thanks Abdu – I haven’t grown hydroponic tomatoes (yet), so sorry I can’t help!

  • Beverly

    Dear Kevin,
    I’ll be teaching children Hydrophonics this summer and organic gardening. How safe and how organic are those general hydroponics nutrients you’ve recommended above? Plus would you be interested in coming to Barbados to see and help even if for a short period, this children’s project this summer.

  • Dear Kevin,

    Good article ! Get’s to the bottom of the subject and makes it very easy for all first timers .

    • Hey Ashish,

      Thanks for the kind words my man. Appreciate it!