Lightweight Expanded Clay Aggregate, or Leca, are small balls or pebbles made from clay that have been heated and tumbled in a rotary kiln. They are porous and absorb water and nutrients added to the water, but they are inorganic and will not break down or rot. Unlike other potting mediums, such as soil, bark, or peat moss, they do not provide any nutrients themselves.
What is Leca used for and how do Leca balls work?
Leca is used in semi-hydroponics or ‘passive hydroponics’ as a growing medium. Unlike true hydroponics, semi or passive hydroponics does not require any pumps. Instead, the porous expanded clay pebbles act as capillaries that wick up nutrient-enriched water and deliver it to the roots of the plant.
Leca also allows ample air and oxygen to reach the roots of the plant, encouraging healthy root growth, while reducing the growth of bacteria and fungus.
The Benefits of Leca
Using Leca as a growing medium offers several benefits, which include:
- A steady supply of water and nutrients to the plant. The little open spaces inside the Leca and the gaps between the clay balls act as wicks or capillaries, drawing water up to the plant. As the balls dry out from evaporation or root absorption, they draw up more water. This means that there is a steady balance between water loss and gain.
- Ample oxygen to the roots of the plant. The air pockets inside the clay balls and the gaps between the balls allow plenty of oxygen to reach the roots. This promotes plant growth and prevents the development of bacterial and fungal infections and the potential for root rot.
- Precise control of the nutrient and PH balance. Lightweight Expanded Clay Aggregate (leca) balls are inorganic and chemically inert. They do not break down or provide any nutrients to the plant, they only deliver the nutrients that you add to the water you use. This means you have full control and can adjust the nutrient balance and the PH level as needed.
- Inexpensive, long-lasting and reusable. Leca balls are inorganic and do not break down or rot. They are inexpensive to purchase (you can buy them new on Amazon) and they last a long time. They’re also reusable so you can use the same balls again and again.
- Easy to use and clean. Using Leca as a growing medium is simple and straightforward. They only need to be rinsed, soaked, and then placed in a container with your plant and nutrient-enriched water. They can be rinsed off again now and again to remove and plant matter or excess salts from the fertilizer used in the water. If you wish to reuse them with a new plant, especially sensitive plants like Orchids, they can be sterilized in the oven or a diluted bleach solution.
How do you grow plants in Leca?
Growing plants in Leca is wonderfully easy to do. There are several methods to use, but essentially you need to place your plant in Leca, in a container that drains freely. You then place that container in a waterproof container with a little water in the bottom. The Leca does the rest.
The most complicated and time-consuming part is getting the nutrient and PH balance in the water right. This may take some trial and error, but if you use the liquid fertilizers used in hydroponics and some PH Up and PH Down, you can get the right balance quite easily.
How to Plant in Leca
To plant in Leca you will need:
- A net pot or nursery pot with holes in it.
- A slightly larger cache pot, deep saucer or any other waterproof container (alternatively, you can use one waterproof container, with a drainage hole drilled in the side about 1/3 of the way up).
- Your plant
- A strainer or colander to rinse the Leca in
- Water and liquid plant fertilizer
- PH Up, PH Down and a Ph test kit/strips
How to Plant:
- Rinse the Leca off under running water, in the strainer or colander, until the water runs clear. If you are using new Leca, this will remove any red clay dust that had formed when the dry Leca was stored and transported. If you are reusing Leca, it will remove any organic matter from the previous plants.
- Soak the Leca in clean water to saturate them and open up the pores inside them. You can do this overnight, or for just a few hours, as long as they are fully saturated with water.
- Prepare the plant by removing it from the potting medium it is currently in and washing off the roots in clean water. Trim any dead or rotting roots away and gently untangle the roots so they can spread freely. The roots should be clean and free of any dead plant matter.
- Fill the netting/nursery pot about 2/3 full with Leca. Shake it around a little to settle the balls down nicely (they’re hard and can’t compact like soil does but if you don’t settle them, they will move around when you add the water).
- Place your plant into the pot, holding it to that the top of the roots are level with the rim of the pot. Spread the roots loosely and evenly over the Leca in the bottom of the pot.
- Add more Leca around the roots and up to the rim of the pot. You can gently shake it again to make sure it is settled around the plant and the plant is secure. Do not press the Leca down around the plant – unlike other potting mediums, the Leca clay balls are hard and do not compact. Pressing them down will crush and damage the roots.
- Mix your fertilizer and water solution. This may take a little trial and error to get right, especially the PH level. You can use any liquid fertilizer made for hydroponics, and the ratio will be on the container. There are many different kinds to try, depending on the kind of plant and what it needs.
- Use the PH test kit to test the PH level (different plants prefer different PH levels, but as a general rule 5.5 to 6.5 will work well for most plants) and add PH Up or PH Down until you get to the right level.
- Lastly, pour the nutrient-enriched water through the Leca so that it flushes down from the top and collects in the waterproof container. There should be water in the waterproof container to about 1/3 of the height of the inner container or just below where the roots extend to. The roots themselves must not be in the water, which can lead to root rot in a plant that has not acclimated to a hydroponic setup.
It can take a while for some plants to adjust to growing in Leca, and it may take some trial and error to get the right nutrient balance in the water for your particular plant. Patience is key. Just keep an eye on it, top up the water when it gets low and adjust the nutrient levels as needed.
How to propagate plants in Leca
To propagate plants in Leca, you can root them in water first and then transplant the rooted cutting into Leca, or you can put the cut stems directly into Leca, using the same process as above. You can use plain water or add some diluted plant food to the water.
When taking a cutting, cut from the new growth that is green and healthy and cut just below a node, where the potential for new roots is best.
What plants do well in Leca?
Most plants will do well in Leca if they’re at the right temperature and have enough light and nutrients. Vegetables, leafy greens, herbs, and houseplants will all work well. Woody or tall/top-heavy plants can be a problem as Leca is quite light and loose, so alone it will not support the plant.
Generally, plants that are sensitive to overwatering will do very well in Leca, while those that require a lot of water will tend to dry out too quickly. Water hungry plants will have you constantly topping up the water and become too high maintenance.
Leca is particularly good for plants that require consistent conditions and like a little humidity. Orchids do very well in Leca, which can make maintaining Orchids simpler and more precise.
The following will all do well in Leca:
- Delicious Monster (Monstera deliciosa)
- Phalaenopsis Orchids (Phalaenopsis Blume)
- Philodendron (Philodendron cordatum)
- Spider Plant (Chlorophytum comosum)
- Pothos / Devils Ivy (Epipremnum aureum)
- Spinach (Spinacia oleracea)
- Kale (Brassica oleracea)
- Beets (Beta vulgaris)
- Mint (Metha sp.)
- Bell Peppers (Capsicum sp.)
- Tomatoes (Solanum lycopersicum)
- Spring Onions (Allium fistulosum)
Leca is an alternative growing medium to soil, peat moss, or bark and is used in semi-hydroponics to wick water and nutrients up to the plant. Leca has numerous benefits, including that it is an inorganic and chemically stable aggregate, absorbs water and nutrients, allows ample oxygen to circulate the roots, and is reusable, durable and long-lasting. It is also easy to clean and maintain. Using Leca as a growing medium allows for the precise control of growing conditions, and it is easy to see when the plant needs more water, repotting, or disease treatment.
Where to Buy Leca Balls
Leca balls can be bought from Amazon.com. For a hefty amount, you can get the 40 liter bag of Leca balls and use it over and over again. If you would like a smaller quantity, you can get the 10 liter bag of leca balls.Leca