How to Convert Plants to LECA: A Semi Hydroponic System

Semi-hydroponics – or “semi-hydro” – is growing plants without the use of organic soil medium. Typically, LECA (lightweight expandable clay aggregate) is the preferred growing medium for this type of setup. It is rather easy to convert plants to LECA or a semi-hydroponic system, and many plants tolerate the conversion surprisingly well.

I actually started my journey into semi-hydroponics because a few of my house plants were really struggling. Hi, my name is Maria and I like to water houseplants to death. Yes, I’m a dreaded overwaterer.

Over time, I started researching about LECA and semi-hydro plant care. Finally, I started transitioning a few plants at a time, to see how they would react. I quickly realized once converted, most started pushing out new growth almost immediately! 

I will confess – my plants have never looked healthier and happier than they do now. 

 

a plant being grown in LECA clay pebbles

So what brought you here? Are you thinking about converting your own plants to a semi-hydroponic system? 

Let me walk you through what has worked and what has not worked for me.

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a very close up look at porous clay LECA

What is Semi-Hydroponics?

Semi-hydroponics uses inorganic material, commonly LECA, to grow plants. The plants are rooted in this growing medium and then placed into a reservoir containing nutrients. These nutrients are absorbed through the wicking action (capillary action) providing the roots with a constant supply of nutrients and water.

Check out my other post on what is LECA and why I personally feel it’s the best growing medium for your houseplants.

There are many different types of setups but this by far is the simplest setup I’ve used.

What's You'll Need for Semi-Hydro Setup

How to Convert Plants to LECA

Note: I prefer to convert less established house plants at first – such as cuttings or newly propagated plants. Mostly, because larger, more established plants can be more difficult to convert to LECA.

Step 1 : Prepare Your LECA

When you first get your LECA medium, you’ll need to do a few things to prepare it before you can start potting your plants.

LECA growing medium in a strainer being rinsed for use
  • Rinse your new LECA – using a strainer and lukewarm water. New LECA is usually covered in a fine dust and may have a little debris in it. It’s important to wash thoroughly before use.
  • Soak your LECA for at least 6 hours before using. Some of the pebbles may float, don’t worry about it. The longer they soak the more water they can absorb and will be less likely to float.
  • If you are reusing LECA – always sterilize it. You can do this with diluted hydrogen peroxide or isopropyl alcohol. Or you can use the method I prefer most, to boil them for 5 minutes on the stovetop. This has never caused my any issues and is more cost effective in my opinion.

Step 2 : Preparing Your Plant

Preparation of your transplant is tedious. It is also one of the most important steps of this whole process. It must be noted, any residual medium will decay, encouraging root rot after you transplant. Therefore, please take your time in preparation before you convert plants to LECA.

getting a plant ready to convert to LECA
  • First, take your plant and gently remove it from it’s container. Try to remove as much medium as possible from the established roots.
  • Under running water, remove the rest of the medium from around the root system. Make sure not to disrupt the roots as much as possible. To do this, I use a soft toothbrush to gentle brush away any residual soil or debris.
checking for healthy roots before converting plant to LECA
  • Check and make sure the roots are healthy. If any are rotten or diseased trim them off using sterile scissors. 
  • Spray the roots with a hydrogen peroxide mixture (using 3% hydrogen peroxide diluted – 2 tbsp per 1 gallon of filtered water – pour in a spray bottle.) Once they are sprayed, let them fully dry. This step helps kill any residual pathogens on the root system and will deter root rot. 

Making sure you trim away any decaying, soft, or decaying roots will also increase the success of your transplant. The hydrogen peroxide spray is a little extra, but I’ve had a lot of success using this step when I convert plants to LECA.

Step 3 : Repotting in LECA

  • Do not repot your plant until the root system fully dries. 
  • Fill 1/4 of your net pot with LECA. Center the plant and its roots in the net pot and pour the remaining LECA around the given roots. Make sure you gently shift the pot around to evenly distribute the pebbles within the roots system.
  • Do not compress the LECA around the root system.
  • Place the net pot in you catch pot.
repotting a plant into LECA
plant converted to LECA and thriving

Step 4 : The First Week

Now, people will differ in how they address the first week after transiting a plant. This is what I have found to be the most successful process for me.

I water my new transplants with Superthrive Vitamin Solution the first two weeks. 

Transplanting can result in shock causing loss of leaves and damage to the root system. Superthrive helps address the shock a plant can go through when being transplanted by supporting the root system during the transition. Depending on the root system, I might do this for a few weeks until I notice healthy new growth.

 

It is also really important that you provide your plant with an environment that is conducive with root growth. Typically, this means bright indirect light, higher humidity and warmth. However, make sure you know the recommendations for your specific species of plant.

 

Step 5 : Adding Nutrients

Since LECA itself does not have nutrients to support healthy plant growth, you need to supply them.

For well established root systems (plants that have converted to LECA well), my go nutrient product is General Hydroponics Flora Series

This series of three nutrients is really simple to use – I use equal parts Flora, Grow and Bloom in every watering cycle. 

General Hydroponic Flora System

Personally, I use 1/4 tsp per gallon of distilled water for the first nutrient cycle. This is after I convert my plants and have performed at least two weeks of Superthrive vitamins. 

Once the plant has adjusted to semi hydro and has had a few weeks of nutrient solution without any adverse reactions, I will then increase the nutrient concentration to 1/2 tsp – of each nutrient – per gallon of distilled water. 

Here’s how I make up my water – starting with 1 gallon of distilled water:

  • Measure 1/4  teaspoon of Flora Micro and mix into the water. Rinse teaspoon.
  • Measure 1/4 teaspoon of Flora Grow and mix into the water. Rinse teaspoon.
  • Measure 1/4 teaspoon of Flora Bloom and mix into the water.
  • Shake the container thoroughly mixing all the nutrients together.
  • Lastly, check the pH of the water using a pH testing kit.
mixing hydroponic nutrient solution with distilled water

Typical houseplants want to be between 5.5-6.5 pH – adjust as needed. The pH testing kit comes with everything you could possibly need to adjust the pH of your water.

Tip: If your pH is too high or acidic (meaning the number is closer to zero), then use pH up to bring it closer to neutral. If the pH is too low (meaning it is closer to 8) then use pH down to increase the acidity.

pH testing kit needed to help convert plants to LECA safely
testing the pH of water and checking is level against a scale

Note: Keep in mind, each bottle in the General Hydroponic Flora Series has recommended values for growing vegetables. Houseplants do not need the same concentration, so adjust accordingly. This is why I use 1/4 to 1/2 concentration for my plants.

It is important to adjust the waters pH once the nutrients have been added for several reasons. Most importantly, it will affect the absorption of the provided nutrients. If the pH does not fall in the correct range the root system will not be able to absorb key nutrients regardless of how much is provided. So yes, you must check your waters pH before filling your reservoir.

convert plants to LECA will help their root system grow

Step 6 : Watering or Filling Reservoir

Once you have your nutrient solution made (either Superthrive or General Hydroponics Flora Series) it’s time to water your plants. 

You will need to add enough water solution in your reservoir to cover the bottom layer of LECA. The wicking effect cannot occur if your LECA is not touching the nutrient solution. But remember a little goes a long way – yes I’m talking to you overwatering peeps! 

Note: You do not want your entire root system sitting in water, it will cause root rot to develop. However, you will notice as roots grow, they tend to grow towards the water. Once you convert plants too LECA they tend to grow rather robust root systems due to the oxygen and nutrient combination.

Tip: I use pots that are ceramic without drainage holes as my catch pots/reservoirs. If you’re concerned about algae, avoid glass containers. With that said, I do use glass for my newly propagated plants so I can monitor root development.

Step 7 : Topping off the Reservoir

It is important to maintain enough water in the reservoir in between flushings (you’ll learn more about flushing in step 8.) The solution in your reservoir will evaporate and be absorbed by your plant, which may lower it below your desired level.

I top off any depleted reservoirs with distilled water. Here’s why…

Water will be absorbed faster than the nutrients in your solution. This imbalance will cause a buildup of salts in your reservoir. Increased salt content can adversely affect the pH of the solution which can cause the root system to be unable to properly absorb water or nutrients.

Florida Ghost converted plant to LECA next to it's catch pot filled with nutrient solution

You will need to experiment with this to see what works best for your plants. Often I have plants that are more thirsty than others. I focus on the thirsty plants when topping off – otherwise I don’t water until it’s time to flush.

Once you convert plants to LECA, you will need to perform a rinse/flush every two weeks. Read more about this flushing process in Step 8 (see below.)

Step 8 : Flushing (every 2 weeks)

Have you ever noticed a white crust that develops on the top of your LECA as it dries? This is an excess of salt from your nutrient solution and can cause the plants overall pH to be adversely affected.

About every two weeks, I perform a thorough flush of all my plants and LECA

To do this, take the plant in the net pot, out of the catch pot/reservoir, and place it under running water. This “flushes” away and of that crusty salt buildup and resets your plants pH.

 

I also recommend you take this time to check (or admire) your plants root system. Check in with your plant and if there’s anything that might need to be addressed (pests, nutrient deficiency, etc….) 

Also, take the time to clean the inside of your catch pot/reservoir before you put your net pot back. Afterwards, refill your reservoir with new pH balanced nutrient solution.

 

In Conclusion...

Now you know how to successfully convert plants to LECA. 

I highly recommend you taking this plunge into semi-hydroponics – your houseplants will thank you I promise!

Disclaimer: I'm not a horticulturalist. I have no formal education on horticultural. Like most of my blog - I share information from experience, research, trial and error, experimentation, and sharing knowledge with others who are actual experts. My goal with this blog is to share my experience and my knowledge of what has worked for me personally Therefore, this blog is meant as a resource of inspiration and to encourage you.

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12 thoughts on “How to Convert Plants to LECA: A Semi Hydroponic System”

    1. Abbie,

      I honestly wouldn’t know, I just don’t have the experience! But I would LOVE to hear how your plants react to tank water vs. nutrients. Sorry I’m not more help!

      Cheers,

      Maria

  1. Hi, thank you so much for this incredibly useful breakdown. It has helped me tremendously! Can I ask if you have successfully transitioned a fiddle leaf fig to leca, and if so, how did you do it? Thank you.

    1. Mia,

      I’m so glad this has helped! I HAVE! They actually liked the transition. Now, I did have a little diva moment after I transferred. I didn’t have a very large fig, but it was happy in the long run. I highly recommend it! It’s SO much better than the overwatering issues I had in the past.

      Good luck and let me know how it goes for you if you pull the trigger and try it!

      Cheers,

      Maria

  2. Hello Maria-

    What are your thoughts on PON vs. LECA and is one better than the other?

    Thank you and thanks for an informative article LECA.

    1. Marv,

      I don’t have a lot of experience with PON. However, for me LECA was an easy transfer, so I highly recommend this venture. I see so many having success with PON, I’m tempted to try in the future.

      Thank you for reading along. Good luck and happy growing!

      Cheers,

      Maria

  3. Thank you so much for the breakdown! I’m excited to try LECA 🙂
    One typo however, your tip on adjusting pH is inverse. pH down is for a solution that is too alkaline/basic (high numbers like 8+ but want to bring it down to 5.5-6.5), and pH up is for a solution too acidic (closer to 4 but want to bring it up to 5.5-6.5 range).
    Thanks again!!

    1. Faith,

      Thank you for the correction! I will edit the copy above to reflect.

      Thanks for reading along and good luck with your LECA endeavors! It really has helped my houseplant journey. 😀

      Cheers,

      Maria

    1. Martin,

      I promise you, this will help! You need just a little water in your catch pot. I wish you all the luck!

      Cheers,

      Maria

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