LECA stands for Lightweight Expanded Clay Aggregate. Yes, we know its a mouthful. In plain English, they are porous clay balls that are made by super-heating clay to around 2,190 degrees F (1,200 degrees C) in a rotary kiln.
You might wonder why these innocuous brown balls are used as a growing medium. Interestingly, LECA granules can retain ~30% of their weight in water and have capillary properties, allowing plants to draw moisture from the clay when needed. This allows LECA balls to act as a mini water source for your plants without drenching its roots.
Still, it seems strange that many gardeners have started opting for LECA over traditional soil. Let’s dive deeper to understand the pros and cons of using LECA to grow your plants.
What are the Pros of LECA?
#1: Makes Watering Easy
As many gardeners know, watering your plant too much or too little can cause yellow leaves, root rot and eventually kill your plant. But knowing exactly when and how much to water your plant can be complicated, as this depends on the type of plant, the season, and even its maturity. In addition, if you keep several plants with varying watering needs, it can be hard to keep track!
LECA makes watering easy, as the clay balls retain moisture and allow your plant to draw water from them as and when it needs. Since your plant is in control of when it drinks and when it doesn’t, you don’t have to worry about overwatering. This is unlike soil where your plant is subject to the moist or dry environment you determine.
Also, when you grow your plant in LECA, your plant’s roots are held up by the clay balls, creating a “false bottom”. Beneath the roots is a layer of balls and beneath that a thin later of water, kept within a closed pot.
This “water reservoir” can be absorbed by the LECA balls to draw water upwards to the roots if water contained within the balls themselves is not sufficient for your thirsty plant. The ability to draw on an extra water reservoir reduces the risk of underwatering. At the same time, the “false bottom” ensures healthy roots are kept away from the thin water layer, so are never waterlogged.
As a result, you will need to water your plant less frequently, and will not need to worry about over or underwatering.
#2: Increased Aeration
When placed in a pot, these LECA balls naturally sit such that there are air pockets between each ball, increasing aeration for the plant’s roots. The clay itself is also highly porous. Aeration is critical to allow for the free exchange of gasses, allowing the roots to breathe.
You may recall from Science class that a plant’s roots take in oxygen and release carbon dioxide. If its growing medium is not airy enough, carbon dioxide becomes trapped and oxygen uptake is hampered. A lack of oxygen prevents the plant from absorbing water and nutrients, stunting its growth.
Compared to soil, LECA is much more naturally airy, promoting healthy growth. Depending on the type of soil, you may need other additives such as perlite or coco chips to promote a looser medium.
Also unlike LECA, soil tends to compact over time, losing its breathability. This is one of the reasons why container gardeners repot their plants in fresh soil every year or two.
#3: Promotes Healthy Roots
Healthy roots are critical to a thriving plant. Roots transport water and nutrients to a plant’s leaves so that they can carry out photosynthesis. They also store energy in the form of carbohydrates and anchor plants in place.
LECA promotes healthy roots by holding roots up and away from the water reservoir at the bottom of the pot. Roots are never waterlogged, so they are not susceptible to root rot. This is not true of soil, where overwatering can easily invite root rot.
Root rot is a general term that can arise from two sources. First, the plant’s roots are sitting in water for too long, causing them to die due to the lack of oxygen. Second, the moist conditions attract common fungi that attack roots and cause decay.
In either case, when left untreated, root rot can kill your plant. It is one of the most common plant ailments dreaded by many gardeners. For more tips on how to save your overwatered plant, check out our watering guide.
#4: Reduces Risk of Pest Infestations
Soil is a living ecosystem. It is estimated that a single handful of soil contains over a million living organisms. Decomposition is a critical process that takes place naturally in soil, involving microorganisms breaking down animal waste, dead leaves, plants and animals.
All of this makes soil a nutrient-rich growing medium which is great for a growing plant. However, because it is a living, organic ecosystem, it can also attract pests like fungus gnats, shore flies, and spider mites.
LECA, on the other hand, is inorganic and chemically inert, which deters pests. It simply does not provide a hospitable environment for these pests to grow, or feed.
As an example, fungus gnats feed on decaying matter and fungus, which are natural byproducts of soil decomposition. They will be much less attracted to an environment without these food sources.
As such, using LECA reduces the risk of pest infestation.
What are the Cons of LECA?
#1: Higher cost of LECA
Arguably the biggest drawback to to changing to LECA is its high cost. Yes it’s true, these baked clay balls cost about 3-4 times more than ordinary potting soil. Added to that, you will need to use a hydroponics fertiliser.
However, LECA can be reused and doesn’t compact over time like soil does. So if you are committed to using LECA, over the long-run it will still make economic sense to do so. Ultimately the choice is yours!
#2: Need to add Hydroponic Fertiliser to LECA
As discussed, LECA does not have any nutrients or minerals of its own. Therefore, it needs to be mixed with a hydroponics fertiliser to create a nutrient-rich environment suitable for growing plants.
Your best option is to use a hydroponic fertiliser whenever you water your plant. Such fertilisers are designed to provide everything a plant needs to survive. This is our favourite hydroponic fertiliser.
Avoid using a general houseplant fertiliser though it might be a bit cheaper. General fertilisers are not suitable as they are meant to supplement your plant with nutrients when growing in an already-rich organic soil medium. They therefore will not be able to meet the holistic nutrient needs your LECA-growing plants require.
#3: Pots need to be without Drainage Holes
As discussed earlier, LECA requires a water reservoir to draw from at the bottom of the container, so pots with drainage holes cannot be used. Depending on whether you have already invested in planters, you may need to spend some money to change your containers over to LECA-appropriate ones.
However, there are many types of containers that you can use without drainage holes. For example, re-purposed jars or bottles are perfect for small plants. Large takeaway containers can also be re-used.
With some creativity, this may not be as big a con as it may seem!
Overall, we think there are some pretty big benefits to using LECA over traditional soil. The ease in plant maintenance, reduced risk of pest infestation and healthy roots are music to the ears of gardeners the world over.
However, the upfront cost of using LECA and specialised fertiliser may not be economically feasible for some people.
If you’re on the fence, one option is to try LECA with one new plant and see how you feel before committing. Or you could borrow some LECA from a friend (they are reusable, remember?).
Which Plants Grow Best in LECA?
Thankfully, LECA is a versatile growing medium. As a rule of thumb, these plants grow well in LECA:
- Any plant that likes a moist but not waterlogged environment
- Any plant that likes to dry out between watering
This includes popular houseplants:
- Monstera Obliqua
- Monstera Pinnatipartita
- Hoya Linearis
- Hoya Curtisii
- Alocasia Zebrina
- Alocasia Polly
What you need for a LECA set-up
- LECA. We recommend this brand from Mother Earth.
- Hydroponics fertiliser. Our favourite from General Hydroponics.
- Any Pot without drainage hole. Optional: net pot.
- Your plant!
Steps to use LECA for the First Time
1. Prepare your LECA
- Using your fingers and tap water, wash the LECA thoroughly to remove dust and debris.
- Pour the LECA into a bucket and add tap water until submerged. Let it soak in water for about 24 hours.
- Change the water and re-fill the bucket, allowing the LECA to soak for a further 24 hours.
2. Transfer your plant
- Gently loosen the soil around your plant and remove it from the original pot.
- Water the roots to prevent transport shock and loosen any soil held within the root system.
3. Repot your plant
- Add LECA to your new pot, filling up to only 1/3 of the container.
- Place your plant on top of the clay balls.
- Add more LECA to until your plant holds firm in place.
- Add hydroponic fertiliser (as directed by the fertiliser instuctions) to the water and water your plant.
Frequently Asked Questions
Can you mix LECA with soil for your houseplants?
Yes, you can. Adding LECA to your soil improves the aeration of the soil. But for the maximum benefits we discuss above, it is better to use LECA exclusively.
Do you need to use a fertiliser with LECA?
Yes, you do. As explained above, LECA is inorganic and does not contain any nutrients. You will need to use a hydroponics fertiliser to ensure your plant gets the appropriate nutrients to grow healthy.
Can I use LECA forever?
Yes. These clay balls are reusable and do not age or compact over time like soil.
To reuse, you must clean the LECA balls by running water over them to wash off dust and debris. Then, add a 3 tsp of 3% hydrogen peroxide per gallon water and pour in LECA. Let soak for 15 minutes and rinse thoroughly under running tap water again.
Deborah is a plant enthusiast and founder of Gardening Collective.