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A Beginners Guide to Hydroponic Nutrients

A Beginners Guide to Hydroponic Nutrients

Nutrient management is the crux of a healthy hydroponic system.

Great nutrient management occurs when growers are:

1) Aware of all necessary plant nutrients and where they come from
2) Supplying adequate nutrients in correct ratios to plants
3) Monitoring and measuring how much of each plant nutrient is available in their system at any given time
4) Making economic and work-flow conscious decisions about how to source and supply nutrients.

Most plants (and all of the crop plants that you’re likely to grow) rely on 16 nutrients to grow and reproduce. Of these, three are available through water uptake and gas exchange (the air): Carbon through CO2, hydrogen, and oxygen.

Why Are Nutrient Levels Important?

The remaining thirteen nutrients are the mineral nutrients delivered to plants through nutrient solutions (dissolved fertilizer).

The overall nutrient level in a solution is measured in EC, or electrical conductivity. The units used to measure EC are ppm (parts per million) or mS/cm (millisiemens per centimeter), although ppm is used more commonly for measuring total dissolved solids. That’s a different measurement for a different blog post. Hydroponics really need to understand the second unit, mS/cm. This is often just expressed as the “EC level”. (For example, “The EC of the solution is 1.8,” with no unit.)

Ideal mS/cm is typically between 1.2 and 3.3. There’s a broad range of acceptable EC levels, and each crop has an ideal range.

The Importance of pH

Supplying the correct ratio of nutrients in adequate levels is only half of the nutrient management picture; the other task for farm managers is to keep those nutrients available to plants, and the main factor influencing that availability is pH.

Nutrients are soluble at different pH values. Check out an absorption chart (there’s one in the article version of this video) to learn more.

Adjusting pH to your ideal range can be done with pH Down or pH Up, which are acids or bases (respectively). Never add both at once!

Liquid or Dry Fertilizer?

There are two main forms of fertilizer: dry and liquid.

Dry fertilizer is mostly used in commercial settings because there’s a lot less to ship (you’re not shipping water), making it more cost-effective. You can also tailor dry fertilizer better to your needs because it comes in separate parts.

Liquid fertilizer is simple to use and great for home and hobby systems. It’s easier to manage since you can just add a certain amount of one liquid to your system water, but it’s more expensive to ship. (Most people on a small scale only buy a little at a time though, so shipping is less important.)

Mixing and Measuring

The best way to mix a solution is to follow the manufacturer’s instructions.

If you’re not using an auto-doser, you’ll still mix it the same way, but you’ll add it to your system bit by bit in equal ratios and test it until it’s at the right level. You’ll get better and better at this over time.

There is a multitude of handheld measuring devices and testers. My favorite suppliers are Blue Lab, Hanna Instruments, and AutoGrow. I’ve used each of these and are currently using AutoGrow’s NutriTest, a handheld meter that measures both EC and pH with the same device. There are a variety of options out there.

Please note that this site is supported by affiliate marketing which means that a small portion will be paid to maintain this site from any purchases made through it. This in no way affects the price of the products on this page.

Conclusion

I hope you found this to be a useful general article on all points of plant nutrition!  The fertilizers below are all well-liked in the industry and will serve you well.

Please be sure to comment and share your questions or what fertilizers you find to be best!


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Darlene Thompson

After having lived in Canada's most northerly territory of Nunavut where outdoor gardening is nigh impossible, I started down my adventure of indoor gardening. I hope you find the various methods as exciting as I do!

20 Comments

  1. Hi and thanks for your informative article. 

    My kids and I have recently gotten into hydroponics and I was wondering what your thoughts are on the safety of liquid vs. dry fertilizers? We currently use the liquid form because we just need to pour it on but as you mentioned, the cost is a quite a bit higher. I just worry that there is more chance of coming into contact with the fertilizer when it is dry. Apart from wearing gloves, do you have any suggestions as to how we can prevent exposure to the product?

    • I would lean towards the liquid as it is easier to measure and you only need gloves.  The dry often poofs out a cloud of dust with nutrients in it that, while being good for plants, may not be so good for humans.  I would also wear a mask if dealing with dry fertilizers.

  2. Economic as well as work-flow conscious decisions are definitely things to think about when it comes hydroponic nutrients. As one who has a few indoor plants I am always looking for valuable information to help with the growing process, and I think you’ve delivered some really quality insights here in order to help do so. I especially like the precise details you’ve provided in regard to pH, as I’m aware that pH is really important to monitor and adjust. I definitely found this post useful and have bookmarked it, and I will be checking out your fertilizer recommendations as well. Great post and keep up the good work!

  3. Being someone who love gardening, i see it important to know what nutrients plants will be needing and also mixing is really vital part that I have failed in a couple and times and have led to the death of some of my plants. I water pH is a bit acidic and has traces of iron when it settles, but i do not know if I should keep up with it, or treat it so it can be more alkaline, what do you suggest?

    • I would definitely treat it to bring it to a more neutral.  General Hydroponics (a very well respected nutrients company) sells a product called pH up that you can find here:  https://amzn.to/35Vhp36.  Just add a little at a time and keep on testing it until you have the right pH.  A little goes a long way!

  4. Thank you for this excellent and informational post.

    I’ve been looking at hydroponics and thinking to myself “it might be a fun endeavor to give a try”.  Of course, after thinking that, I started looking into it and realized it’s a lot more involved than I thought.

    Still, I really want to try my hand at it and your post on hydroponic nutrients is eye-opening and helped me to better understand some of the requirements.

    Thanks again,

    Scott

    • Thank you so much, Scott.  I will be doing a complete series on nutrients and other things to be aware of in hydroponics so stay tuned!

  5. I have been interested in hydroponic growing for a long time. I live in an area where we don’t have a very long growing season and since I love fresh veggies, it can be expensive to enjoy them throughout the year. I have seen several units for hydroponic growing. Your article made me realize there is a lot more to growing plants. I don’t fully understand the pH and other terms you used. Do you have a more comprehensive look at these topics? It isn’t just add water and go… A friend of mine introduced me to the idea of hydroponic growing and I have been looking at it for a while now. The problem for me has been cost. I guess if you figure the cost of the veggies in the store, it would easily pay for itself. I appreciate you sharing this information. It really got me thinking about this more in-depth.

    Karin 🙂

    • Thank you, Karin.  Yes, the fresh vegetables will definitely pay for many of the systems I have espoused on this site.  Stay tuned because this is just the first of a series of articles I will be doing that will also cover pH and a bunch of other things one should be aware of!

  6. I have always wanted to try hydroponic gardening.  Your beginners guide is inspiring me to give it a try.  The monitoring and measuring sound like the most difficult part of the process.  It sounds like there needs to be some trial and error to dial  in the right EC before adjusting pH levels and fertilizer dosing.  I think after reading your article I am ready to give hydroponic gardening a try.  

    • Thanks a bunch, Stacy!  I sure do hope you give hydroponics a try – I just love it.  The EC and pH are not at all trial and error and there are some very inexpensive units to measure this.  Stay tuned as tomorrow I will be posting more on these topics!

  7. Hi! I’m really glad I found your site. I started researching about NPK and found one of your posts. And have continued reading and you have so much information here, well organized and in a way that’s so easy to digest that I have bookmarked you site.

    I needed to refresh some of the basics concerning hydroponic nutrients. I didn’t know there are 16 plant nutrients. And I also refreshed the idea of these 13 mineral nutrients. Great post. Thank you very much!

  8. Hi! I have recently been reading a discussion why Calcium should be considered a macro nutrient. But at the end of the discussion I believe it should be keep in the classification as a secondary nutrient, as it’s right now.

    I have been asking myself questions concerning what EC value should be for individual crops. I’m glad you’ve helped me with this. Thank you very much!

    • Yes, calcium is truly needed but it isn’t one of the big three as you don’t need as much of it as NPK.  Stay tuned for more articles on pH, EC and more!

  9. Hello Darlene, plants area really sensitive to so many changes and nutrients added to it and so is it necessary for gardeners to be watchful of whatever it is we apply to them. One of the factors that leads to the death or slow growth rate of plants is the watering system and how good that water is. Water pH level should be checked regularly because these things changes naturally. Cheers.

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