What is LECA? How to Use LECA for Plants (Your Final Guide)

Have you ever wondered why some folks grow their plants in round orange balls instead of soil? LECA, also known as clay pebbles, has been growing more popular. But what exactly is it? Why do people use it? I’ll answer all of these questions for you and more in this article!

LECA, lightweight expanded clay aggregate, is made of clay and brick dust and is commonly used in gardening. To use LECA for plants, 1) clean it, 2) use water-propagated plants, 3) set the plants in it, 4) create a nutrient solution, and 5) water the plant with nutrients.

Aside from it being aesthetically pleasing, using LECA for plants is extremely popular and has plenty of benefits. But first, it’s best to understand how it’s made and what are the pros and cons of using it. Here’s everything you need to know about LECA balls!

What is LECA?

LECA stands for lightweight expanded clay aggregate. These are balls made with clay and brick dust. The clay balls are processed in a rotary kiln at 2,190°F, forming air pockets, which makes them light and porous. Clay balls are widely used for semi-hydroponic and hydroponic gardening.

The first thing you should know is that LECA means lightweight expanded clay aggregate.

It is a combination of clay and brick dust. Then, it is put in a rotary kiln at around 2,190 °F (1,198.89 °C). As the clay rotates in this high-heat environment, it pops like popcorn and produces air bubbles inside!

This leaves us with round orange balls that we know today as LECA. Because of their round nature, they’re also commonly called clay pebbles.

When you look at the center of a LECA ball, you’ll see that it has a honeycomb-like structure.

These pores make the LECA extremely lightweight. Its high aeration and large particle sizes make it an excellent material for plants, especially in hydroponics.

You can use it in different ways, as you’ll find out later on. Even better, LECA can be easily found in plant stores, and the most popular way is to use it as an alternative to soil.

How to Properly Use LECA for Plants (5 Easy Steps)

To use clay pebbles for plant cultivation, plant owners must first clean the LECA. Then, water-propagated plants should be chosen and set in LECA. Afterward, create a nutrient solution and water the plant with it.

Before you start using LECA, be sure to have these things handy: hydroponic nutrients, plastic pots with drainage, and catch pots.

When you’re first starting out, it can be overwhelming trying to understand how to even use clay pebbles to begin with. So to help make the process easier for you, here is a step-by-step guide on how to properly use LECA for plants!

1. Clean the LECA

New LECA can be dusty and must be washed before it is used, as the dust can be harmful to breathe in. Wash the LECA thoroughly and let soak for 12–24 hours. Clean the LECA outdoors to prevent the dust from clogging pipes.

When you buy your first bag of lightweight expanded clay aggregate, there’ll probably be some dust. This is totally normal. All the dust will come off whenever the clay balls rub together.

Before you use it, wash the LECA until the water runs clear. The clay dust can clog pipes, so try doing this in an outside drain rather than indoors.

Alternatively, you can let the clay balls soak in water for at least 12–24 hours before using it.

This is up to you, however, as many gardeners tend to skip this step and still have success. But if you have a new bag of LECA with lots of dust, I suggest letting it soak to let the dust and impurities come out as much as possible.

Find out the 4 Best Ways to Clean Hydroton for Reuse!

2. Use Water-Propagated Plants

Young plants propagated in water are most likely to survive when planted in LECA. Plants in soil can be moved to containers with clay balls but they may have difficulty adjusting to the change of medium, especially if they have fine roots.

Keep in mind that not every plant will grow well in LECA. Plants with more delicate roots, like marantas, are less likely to thrive in these lightweight expanded clay aggregate balls compared to orchids with thick roots.

Water-propagated plants will easily adjust and grow in LECA than other plants.

But if you plan to transfer a plant from a soil-filled pot to LECA, you’ll first need to remove as much of the soil as possible. Any excess soil left on its roots could cause it to rot.

Personally, I would not recommend using large or high-value plants, especially if it’s your first time. These plants are more likely to fail, so consider using plants you don’t mind losing.

3. Set the Plants in LECA

Fill ⅓ of the pot with LECA and position the plant roots in the middle. Then, pour the remaining balls around the roots and tap the pot to allow all of it to properly settle.

The roots should not be on the bottom of the pot when you’re growing plants in lightweight expanded clay aggregate. So, pour a layer of LECA first before setting the plant roots on top.

Once the plant is nicely positioned, carefully add more clay balls to surround and cover the roots. Afterward, gently tap the pot on a flat and solid surface like a table to help all the balls adjust and settle in place around the roots.

You’ll likely see gaps between some LECA balls, but this is fine. These clay balls should be placed comfortably around the roots but shouldn’t be too compact.

4. Create a Nutrient Solution

After the plant is placed in LECA, use general hydroponic nutrients and mix it with a liter or gallon of water depending on the instructions. Feed new plants weaker solutions at the beginning to prevent fertilizer burn.

Once the plant is in LECA balls, it’s time to create its nutrient feed. Since plain water and LECA have little to no nutrients available for the plant to absorb, it’s essential to give plants in clay balls nutrients for them to thrive.

The first thing to do is to test the pH of your water with a pH testing kit. The ideal water pH would be between 5.5 to 6.5. Below is a PH meter on Amazon that is loved by plant owners and is commonly used for hydroponics.

Besides that, this fertilizer on Amazon is excellent for general hydroponics and comes with detailed instructions.

Follow the instructions for your general hydroponic nutrients and mix them in a bottle of water. I suggest using a liter to make it easier for you to calculate the measurements. Shake the solution each time more fertilizer is added.

Grow bigger plants using LECA | Semi hydroponics for houseplants

When you first start, give your plants a weaker concentration of nutrients to help them adjust and avoid fertilizer burn.

Pro Tip: Use a syringe to measure how much of each solution you need per liter of water.

You can also make this fertilizer-imbued water in batches if you’d rather not play mad scientist every time you need to water all your plants growing in LECA.

5. Water the Plant With Nutrients

To create a water reservoir, keep the plant in a catch pot and pour the nutrient water until it sits directly below the plant roots. This water must be changed twice a month to provide the plants with oxygen and nutrients.

Now that your fertilizer solution has been made, add the nutrients to your plant.

Pour the water into a third of the pot. The water should sit below the roots but should not be touching them or covering them completely.

Learn why in our article, Should All The Roots Be Submerged In Hydroponics?

The roots will absorb the moisture and nutrients they need through the porous clay balls using capillary action. This happens when the water is naturally wicked up through the rest of the LECA.

Keep the plant in a catch pot to create a water reservoir. Change the water every two weeks to give the plants fresh nutrients and oxygen, and you’ll have a happy plant growing in LECA!

The 4 Benefits of Using LECA for Plants

Many plant owners and gardeners like using LECA because it 1) encourages faster plant growth, 2) increases aeration, 3) prevents fungus gnats, and 4) is reusable.

It might be puzzling trying to understand how these inorganic clay particles are useful in gardening. Let’s clear up the confusion and discuss the reasons why LECA can be helpful for your plants.

1. Faster Plant Growth

Plants in LECA grow faster than plants grown in soil. This is because the clay in these balls will attract nutrients and provide them directly to plant roots when needed.

So long as they’re given consistent nutrients, plants tend to grow faster in lightweight expanded clay aggregate than in soil. As a result, plants can absorb nutrients more efficiently from LECA.

Plenty of plant owners find that using LECA led to faster growth compared to regular soil. But, oftentimes, they’re not sure why it happens.

A very simple but scientific way to explain this is that clay has a negative charge and will attract molecules with positive charges.

These molecules are usually found in nutrients that our fertilizers have. So when a plant is grown in LECA balls, it will draw nutrients directly from the balls and absorb what is needed.

Since the plants are being given exactly what they need, they often develop much faster!

2. Increased Aeration

LECA is extremely fast-draining and helps increase aeration. Water will drain from each ball within about 7 seconds. As such, clay balls are unlikely to suffocate plant roots and cause root rot.

Since lightweight expanded clay aggregate balls have an abundance of air pockets, they’re lightweight and rarely become compact. This makes it perfect for hydroponic systems as they’ll provide more oxygen for the roots and ensure they don’t rot.

Heavy waterers will also benefit from using LECA. As we’ve tested in our hydroton vs perlite article. A full cup of LECA and water drained in around 7 seconds.

Since LECA is so light and allows water to pass through quickly, it’s very well-draining and lowers the chances of plants getting waterlogged.

This pack of clay balls on Amazon provides excellent aeration and is great for indoor gardening.

Because it’s much harder to experience excessive moisture when growing plants in LECA, root rot and anaerobic potting mediums can also become a thing of the past.

3. Prevents Fungus Gnats

Fungus gnats do not like laying eggs in LECA and will be discouraged from breeding. Hence, using clay balls will reduce the likelihood of fungus gnats invading homes and gardens.

The biggest praise people often have about lightweight expanded clay aggregate is that it eliminates the chances of fungus gnats invading and damaging their gorgeous plants.

A single fungus gnat female can lay more than a hundred eggs at a time in soil. In effect, fungus gnat infestations can be near impossible to battle. But using a different growing medium aside from soil could solve the whole problem.

Since LECA is made of clay and is different from soil, it provides a less-than-suitable environment for egg-laying.

Of course, this will only directly protect your plants in LECA. Nevertheless, using clay pebbles as a growing medium will reduce the overall possibility of fungus gnat infestation in your home.

4. Reusable

Lightweight expanded clay aggregate, or LECA, is nonbiodegradable and can be reused for years with proper cleaning. It can easily be sterilized and used for other plants. Additionally, clay pebbles have a hard shell and don’t break easily.

Last, but certainly not least, LECA has a long shelf life. What’s even better is that it does not readily break down, making it ideal for container plants.

While potting soil can last for years, it can easily degrade in quality or get exposed to harmful plant pathogens. Sometimes, the only thing you can do is dispose of it.

LECA balls, however, can be cleaned and reused multiple times without becoming poor in quality. As such, your overall waste in the garden will be reduced and will be much more sustainable as well.

These clay balls are also extremely tough and not easily destroyed—to the point they are commonly used in construction. So you never have to worry about any degrading LECA!

The 4 Problems of Using LECA for Plants

Drawbacks to using LECA in gardening include the 1) lack of nutrients, 2) high maintenance, 3) expensive cost, 3) and quick sodium build up.

Now that you’ve gone over the benefits, here are the negatives to keep in mind when it comes to using LECA with your plants.

1. Has No Nutrients

Leca is inorganic and does not have any nutrients. Because of this, it has little to no beneficial microbial activities, requiring more frequent fertilizer application for plants.

An important note you should know is that LECA is completely sterile. Since this is an inorganic material, it naturally has no organic or microbial activity whatsoever.

Remember, the clay in lightweight expanded clay aggregate balls was processed under very high heat. Whatever organic residue lived in the clay was probably burned out as a result.

A good way to view LECA is to remember that it serves as a vessel for plant roots to use and absorb nutrients.

But clay pebbles do not have any nutrients in them whatsoever. So, there will be fewer microbial activities or natural cycles for the roots to benefit from when plants are cultivated in them.

This means you’ll have to constantly feed your plants fertilizer to ensure they’re thriving. You’ll have to do this regularly as well since the fertilizer can easily wash out.

2. Can Be High Maintenance

Plants grown in LECA balls can require more maintenance. When used in a semi-hydroponic system, LECA-grown plants need regular feeding and cleaning, which can be more difficult for busy plant owners to maintain.

Using clay balls can be difficult when you’re used to pouring plain old water into your plants’ pots and leaving them.

Since LECA balls have no nutrients, the plants grown in them will need more hands-on care. As I mentioned earlier, plants grown in lightweight expanded clay aggregate balls must be fed nutrient solutions every time they’re watered.

Additionally, the LECA must be flushed regularly to prevent minerals from building up.

Because of this, LECA may not be ideal for those not strongly consistent with plant care. The increased plant growth can also require more frequent repotting, making growing the plants more of a hassle.

The difficulty of using LECA will depend on your plants and the level of plant care you can provide. But when it comes to clay balls, there are more factors and steps than growing plants in soil.

3. Can Be Expensive

LECA has a higher initial cost and can be more expensive than other substrates, such as soil and moss. Aside from the LECA balls, the owner must buy hydroponic fertilizer, netted pots, and more additional materials for maintenance.

The LECA itself might not be too expensive. Once you include the cost of the nutrient solutions and special pots though, the up-front cost will quickly add up.

Additionally, the nutrients used in hydroponics typically can’t be used for plants grown in soil, which limits their use.

Learn more about Using Hydroponic Nutrients in Soil Plants.

I know someone who paid over a hundred dollars just to set up one plant in LECA correctly. So, if you don’t have any serious plans with LECA and you’re strapped for cash, it might be better to try it out at another time.

4. Builds Up Sodium Quickly

The high absorption rate of LECA can be detrimental as it will absorb large quantities of sodium. This excessive sodium can harm and kill the plant.

Lightweight expanded clay aggregate balls don’t just attract nutrients. They can also absorb sodium.

LECA can absorb high amounts of sodium, eventually developing a white crust. This indicates that the salt has accumulated and is sitting in the balls.

You might think this isn’t such a big deal. But if LECA is left neglected, the plant in it will eventually die due to too much sodium.

This frequently happens when using tap water. However, even if you don’t use tap water, the clay pebbles will still need to be flushed or cleaned to prevent the sodium from building up.

2 More Ways to Use LECA for Gardening

In gardening, LECA can be used in two different ways: as a 1) soil amendment and for 2) top-dressing plants.

But what if you’d rather use lightweight expanded clay aggregate in different ways instead of using it to replace soil? Luckily, there are as many ways to do things as there are plants in the world.

Check out these two different ways you can use LECA for your plants.

1. Soil Amendment

Leca can be mixed with your usual potting mix to help increase aeration. A good ratio for heavy waterers is 60% soil and 40% LECA .

By mixing in some clay balls, water is less likely to sit in the pot and smother your plant. Additionally, the soil is less likely to become compact and should stay airy for longer.

2. Top-Dressing

This method is ideal for those who don’t wish to replace soil but still want to use LECA to prevent fungus gnat infestations in the garden.

You don’t need to convert all your plants to LECA as a growing medium if you don’t want to!

Instead, you can simply use about an inch of clay balls as a top dressing to discourage fungus gnats from laying eggs in your plants. Just like that, the fungus gnats should be unable to breed in and infest your LECA-dressed houseplants.

FAQs

Is LECA good for all plants?

Although LECA has many benefits, not all plants can live and survive in it permanently. Larger plants or plants with delicate roots will have great difficulty adjusting to such a growing medium and are better kept in soil.

Can plants live in LECA forever?

Plants can be kept in LECA balls for long periods. However, if the plant grows too large, it might be easier to transition them from clay balls to soil. Due to their lightweight nature, the balls may be unable to support large root systems, requiring the plant to be moved to soil.

Summary of Using Leca For Plants

LECA or lightweight expanded clay aggregate is a common gardening material made using clay and brick dust. The balls must first be washed. Oftentimes, water-propagated plants grow best in LECA. Place the plants in the clay medium and water them with a diluted hydroponic fertilizer solution.

There are many benefits to using LECA for plants; it can encourage faster plant growth, increase aeration, prevent fungus gnats, and can be reused after cleaning. The drawbacks to using LECA balls, however, are that they have no nutrients, can be high maintenance, can become expensive overall, and cause sodium build-up quickly.

Sources

• “LECA balls” by n/a in University of Washington
• “Hydroponics: The power of water to grow food” by Valentina Lagomarsino in Harvard University
• “What is your soil cation exchange capacity?” by Ron Goldy in Michigan State University
• “Small-scale hydroponics” by Natalie Hoidal in University of Minnesota