What is this Absurd Thing Called Hydroculture?


Putting plants in clay pebbles instead of soil! What is this absurd thing called hydroculture? Hydroculture is hydroponics, except instead of using just a nutrient solution as a growing medium, hydroculture uses an inorganic solid growing medium to stabilize the plant and root system. 


Expanded clay aggregate or small pieces of clay is used as one of the most popular growing mediums. This Expanded clay aggregate is also known as Hydroton or LECA (Lightweight Expanded Clay Aggregates). Hydroculture can be thought of as passive hydroponics since it does not require a mechanical pump to transport the nutrient water. 



How Does Hydroculture Work?

Hydroculture vase
Hydroculture Plant growing in LECA in a glass vase, Source


Some growers start seedlings in peat moss or other typical organic soils. The soil is then washed off and removed when the root system develops and establishes itself. 


The plants are then placed into a container. LECA is then poured around to replace the soil. Several inches of water is allowed to accumulate at the bottom of the container. LECA wicks this water upwards to the roots of the plant. It is relatively easy to maintain plants once they have acclimated to the system. In fact, you won’t need to water the plants for six weeks at a stretch.


Watering LECA based plants are straightforward. You won’t need to add more than an inch or two of water. You can always make use of small water meters to know the amount that you have poured. LECA is an inert medium, which means it doesn’t contain live organisms. You need to mix water-soluble plant nutrition in the water that you give to your plants.


Why would anyone do such a thing? Using LECA?


LECA Clay pebbles
LECA Clay pebbles, Source


There are many desirable growing properties that make LECA the most popular hydroculture growing medium.

  • Porous: LECA provides abundant oxygen and air to the plant roots. Many plants die because of a lack of oxygen.
  • Capillary properties: LECA wicks water upwards. In some cases, it can wick up to 8 – 10 inches of water.
  • Lasts long: LECA doesn’t decay or compact over time like organic-based soils. This helps the roots get the air they need.


LECA hydroculture kits can easily deliver ample nutrients and water to the plant roots while providing the root zone with abundant oxygen. This gives plant roots an ideal growing environment which is critical to the plant’s overall health.


Pros of Hydroculture

  • Reduced risk of pests – You won’t need to deal with pests when you use LECA hydroculture kits instead of soil. This is because roots in LECA are less prone to root rot than in soil. LECA doesn’t attract pests and other bugs as well.
  • Plant care is easy – LECA can regulate moisture to a great extent which prevents overwatering. Your plant won’t need to be watered frequently. However, you need to make sure there is enough water for LECA to soak up.
  • Less weekly maintenance – LECA tends to retain moisture in a hydroculture pot. The plant roots get exactly what they need at their own pace. You should add water only when you feel that all the water has been absorbed by the LECA.
  • Reusable growing medium – LECA can be reused as long as you maintain and clean it. However, you cannot reuse soil without adding fertilizer to it. The previous plant would have absorbed all the nutrients.


Cons of Hydroculture

  • Higher initial investment – LECA comes out to be 3 – 4 times more expensive compared to soil. This can seem like a significant investment for some people especially when you have to get supplies. However, you should know that LECA comes out to be cheaper in the long run.
  • Takes more work initially – While using soil, it is as simple as putting the soil in a pot and planting in it. However, LECA requires more work. You would need to wash away all the dust from a new bag of clay balls. This can take as long as 30 minutes.
  • Hydroculture pot choices are restricted – Most types of hydroculture pots come with a hole at the bottom since they are designed to be used with soil. You need drainage with regular soil. However, with LECA you need pots that can store water without them dripping at the bottom. You may not have the same type of hydroculture pot options as with LECA.
  • Special fertilizer is required – LECA is an inert medium. You would need to add special liquid-based fertilizer to help your plants stay vibrant and healthy. In fact, you can’t use regular plant fertilizer. You would need to use one designed for hydroponics.


What Grows Best with Hydroculture?


Roots growing through LECA clay Pebbles
Roots growing through LECA Clay Pebbles, Source


Hydroculture is new to the US, but it has been in use in Western Europe for decades. There are several interior houseplants that are specifically sold as hydroculture plants. If you are just starting out, you should think of using plants sold especially as hydroculture houseplants. You can also try growing your own plants if you have green skills. Make sure you use hardy plants with developed root systems.


Can You Convert Plants from Hydroculture to Soil?

Hydroculture houseplants can be converted from their existing soil base to surviving in a LECA substrate. However, you would need to be patient and take extreme care while washing away the soil from roots.


It is normal for plants to experience a little stress in the beginning. You may notice leaves wilting, but this is normal. Do not overwater the plants or overfertilize them. This may cause root rot.


Planting Systems Mistaken for Hydroculture

Hydroculture is often confused with hydroponics and water culture. While they have several similarities, they are not the same. Hydroponics is water-based growing while hydroculture makes use of an inert rock-based medium. Water culture can be a combination of hydroponics and hydroculture, where the plant is held in a net cup filled with LECA and then placed into a raft that floats in recirculating nutrient water. 


Unlike Water culture, roots in a hydroculture system should not be suspended in water and you should never overwater the LECA medium. Overwatering can cause pests or fungus that will spoil the plant root. Hydroculture cannot work if there is no air in the root zone. Air is critical to keeping plant roots healthy.




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HI! I'm Bobby, an entrepreneur, inventor, green builder and urban farmer. I've been a custom home builder since a kid and an avid gardener. The critters, bugs and climate outside our new home forced me to check out some new ideas in gardening. I found out about Hydroponics and have spent years learning the best techniques to build the best, most efficient, home hydroponics systems. I built one of the first ever, small scale, mobile hydroponic systems. Would you like to know how I did it?