The most exciting thing about plant care is experimenting with different mediums to grow your plant family. We’ve been exploring different ways to grow plants in water—one of those ways is utilizing LECA.
The plant community uses the terms “leca” and/or “hydroton” to refer to all types of expanded clay. LECA, specifically, stands for Lightweight Expandable Clay Aggregate - a collection of baked clay pebbles that expand when you soak them in water. You can use LECA for propagation, or you can have your plants live in it!
Fun fact: LECA is the name of a specific brand of expanded clay, which has since gone out of business due to the company-owned clay mine becoming depleted. Some common brands of expanded clay are Hydroton, Hydrocorn, and Hydro Korrels.
LECA can vary depending on the brand based on size, size variation, smoothness, and porosity. Each of these qualities influences your plants’ growing characteristics, so it’s essential to understand the differences and how they may affect your plants. Let’s go through them one at a time.
The size of the individual clay balls directly affects how much room your plant has to grow its roots. Larger clay balls allow more room for root growth, allowing for better oxygen delivery but less structural support for the plant.
Size variation focuses on the range of sizes within a LECA mix. We find that a LECA mix between small and large pebbles creates an excellent medium for your plant because the growing medium ends up being a bit denser. This allows for good oxygen delivery while also offering good structural support.
Smoother LECA packs loose, so it gives the plant more room for root development and oxygen delivery. The downside is that smooth LECA, much like larger LECA, offers less structural support.
Rougher LECA, on the other hand, packs denser and provides enough space for roots to latch onto the rocks. This is good, but it comes at the cost of less oxygen delivery. In addition, if or when you decide to repot the plant, it might be more complex and disruptive when using rougher clay balls. For this reason, rougher LECA is more suitable for vegetables and plants you don’t plan on repotting. One thing to also consider is that rougher LECA is harder to clean, so you’ll need to make sure to clean them between every reuse.
Now, let’s talk about porosity—or how much water each of the balls can absorb. The more porous the LECA, the more absorbent they are and the better the water moisture. This is great for most non-agricultural styles of hydroponic growing.
Before potting your plants in LECA, it’s critical to flush the clay balls until the water runs clear. When you first use LECA, you’ll find that they are covered in a dry clay residue from the clay balls making contact with each other while being packaged. The dust can cause health problems for your plants, so it’s important to wash this off before use.
If you're feeling a little lazy, you can also just soak the LECA for 2+ days to make sure you get rid of all the crud out. For high-value plants, we recommend a second soak for another day or so. You would want to change the water and let the LECA dry in between soakings.
It does require some patience, but this step will save you time, money, and energy later on!
The size of your vase depends on how big you want your plant to grow. However, you don’t necessarily have to be married to a particular size, being that you can always transfer your plant into a bigger pot later on.
We have also noticed that the transparency of the pot can influence how your plant grows in LECA. There are pros and cons to both. For instance, clear vases are more susceptible to algae—making the LECA harder to clean and potentially disrupting the root system. Non-clear pots, on the other hand, help lessen the risk of algae, but you can’t accurately track water levels, so you’re left guessing as to when you should add more.
A good rule of thumb is to choose your pot based on where you plan to keep your plant in LECA. For example, if you plan to have your plant in more direct sunlight, an opaque vessel is probably best—otherwise, algae growth is likely. But, if your plant will be out of direct light where algae growth is less substantial, a transparent pot works great.
Now that you’ve prepared your LECA and your plant’s new living space, it’s time to pot your plant in LECA! Before we get started, we have found that this growing medium works best for plants with an established root system.
First, if you’re transferring your plant from soil, you’ll want to start by gently removing all the dirt from your plant. Since LECA stays so evenly moist constantly, any soil left on the plant will be wet all the time and can lead to root rot or fungus.
Next is putting the root system inside with LECA. This step is pretty self-explanatory because it’s just like potting with soil. Grab your pot and fill it up to about ½ - ¾ of the way with LECA and submerge it in water. Then, place your plant's roots in the pot and fill the rest up with LECA. Try to arrange the roots so that they don’t touch each other to ensure that it’s less likely to pass rot on to the other roots if one root starts to decline.
The last step is just to add water! We recommend adding your liquid nutrients to the water before filling up your pot to distribute nutrients evenly. Then, pour in the nutrient water until it has just reached the bottom of the root system to avoid the roots sitting in water while still creating a moist environment.
Many people also use LECA in combination with other growing mediums! For instance, we’ve seen people put peat moss about 0.5-1 inch within LECA. The additional support of root growth and stimulation leads to better growth overall. This method is more common for plants without developed roots systems or has early infantile root systems. So, to simply put it, LECA with peat moss helps baby plants with water and nutrient delivery during their early stages of maturity, but not so much later on in plant growth.
However, peat moss is a non-sustainable resource that is pretty disruptive to environments. So we will be doing experiments of other mediums (like co-co cor) to help the evolution of this plant space and continue to find ways to move away from it. Stay tuned for more updates from us on our Instagram @modernbotanicalshop.
What we DON’T want to do is have the plant’s roots sitting in water. So avoid filling the entire pot or vase with water. Instead, you should bring the water up to just below the bottom of the root system. This puts your plant in charge of how much water it's receiving, and it can sip on the water that’s been soaked in by the LECA.
You don’t have to worry too much about refilling the water since LECA allows for the plants to grab water when they need it. However, when you see that the LECA is drying up and the roots are growing closer to the bottom of the pot, you’ll want to refill the water.
Nutrients offer long-term growth support, especially for plants in LECA. The liquid solution of water and hydroponic nutrients essentially replaces the nutrients that the plant would get in soil. We usually add 1-2 drops to the water before pouring it into your pot and repeat this step every 1-2 months.
Finding the right nutrients is a topic of its own, but we'd recommend finding a nutrient solution intended for hydroponic growth. We have a great nutrient solution to support plant health in our shop that you can check out here.
You should clean your plant in LECA about once every 1-2 weeks. This is a great time to check the root system and adjust the plant’s placement in the pot as necessary. If you’re planning on reusing the LECA, make sure to clean (or at least rinse) the clay before repotting your plant. Also, you want to be careful when removing the roots from the LECA because the roots can get stuck to the clay and the inside of the pot.
This growing medium has so many fantastic benefits beyond being the new fad in plant care. Of course, LECA may work differently for everyone (what works for us may not work for you) based on different environments and care routines. Nonetheless, it’s a really fun medium to work with and to learn more interesting things about plants.
We would love to hear about your experiences with LECA! Follow us on Instagram @modernbotanicalshop for more growing tips and tricks!