Cultivating plants without soil – it sounds like science-fiction, but it is happening today.
In fact, gardening without soil has appeared throughout history. Think about the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World – they had envisioned this too!
In a hydroponic system, an inert growing medium is used as an alternative to soil. This growing medium acts as a substance that the roots can secure themselves on.
An ideal growing medium retains and stores just the right amount of nutrients, which it then delivers to the plants. Growers started realizing soon enough that clay pebbles are perfect for this job.
Today, clay pebbles have become the go-to alternative for soil among seasoned gardeners. The results are high-quality yield and rapid growth.
Let’s understand more about our growing medium before we learn how to make full use of it.
Guide To Clay Pebbles In Hydroponic Systems
Table of Contents
What Are Clay Pebbles or Hydroton?
When pure clay is heated up to temperatures over 2000°F, it breaks up into a form that resembles pebbles. They are small, oddly shaped like popcorn, and about the size of a marble. Hard, but very lightweight – these are called clay pebbles, hydroton, clay balls, or light expanded clay aggregate (LECA).
The heating process fills up the clay pebbles with air pockets, which is what makes them so great for the plants. These air pockets act like tiny, expandable storage spaces that allow the upper nodes to receive a healthy amount of moisture and nutrients. And because of the porous structure of these clay pebbles, the medium can provide plenty of oxygen to roots.
We have only scratched the surface on understanding the growing popularity of using clay pebbles as a soil substitute. Clay pebbles remain one of the most favorite media for hydroponic systems (utilized in various techniques such as ebb-and-flow or Dutch bucket). Here’s where we tell you why :
Hydration and Drainage
The first bit is a no-brainer. Because of the porous structure formed by air bubbles, water and moisture retention is good. This keeps plants hydrated with water and all the nutrients that they need – provided there is a good supply of water.
However, the capacity for holding air bubbles also results in greater percolation. This is especially useful in ebb-and-flow systems, where water filled with nutrients is allowed to flood the media. Clay pebbles are great absorbers of water, but they just as easily drain out the excess water. This prevents roots from becoming oversaturated.
The space between each pebble is visibly greater than smaller particles like perlite. As mentioned earlier, hydroton has great percolation abilities. Other than drainage and storage, smoother percolation also prevents clogging and blockages.
Even if debris gets stuck in between the pebbles, and even with algae and fungus accumulation on the top layer, water still gets drained easily. This feature is particularly desirable in media used for ebb-and-flow systems.
Easy Transplanting and Harvesting
At first glance itself, you will realize that this growing medium is quite loose. Loose growing medium automatically makes transplanting and harvesting an easy task.
Clay pebbles don’t lose shape throughout the entire growth process, so you may easily remove seedlings and plants from their containers at any time. It’s quite a different harvesting experience, especially when compared to traditional harvesting. No more digging and pulling to get your plants out!
Sterile and pH Neutral
Clay pebbles are washed and sterilized before being placed in containers. This means that they do not disturb the composition of the nutrient solution by introducing pests. Clay pebbles are also pH neutral, with a recorded pH of around 7.2 to 8 when they are taken straight out of the bag.
High Biological Surface Area (BSA)
A higher BSA means that there is more surface area habitable for microbes. These microbes are capable of producing nutrients that are healthy for plants.
Clay pebbles or hydroton are derived from clay, which is just pulverized soil. Therefore, it is a natural medium rich in minerals and natural components. The amount of clay required to make hydroton is also reasonable and is far from disproportionate to the earth’s supply.
The process of turning clay into clay pebbles is a process that does not involve any harmful chemicals. A simple kiln furnace is used to fire up the clay to form the expanded growing medium as we know it. Needless to say, clay pebbles are renewable.
Long Life Span
There are many ways you can help prolong the life of clay pebbles. It helps that they can be reused with a few tweaks on the part of the grower.
Unless there is a lot of salt buildup, clay pebbles can almost be reused indefinitely. Simply wash off any silt or organic matter that has built up, sterilize, and you are good to use it for another cycle.
Before you start this cycle and grow your own garden with clay pebbles, it helps to keep track of some of the complications you may face along the way. But don’t worry; in the end, we will provide a guide and ample tips to work around these drawbacks.
Don’t be confused, drainage is a good thing when avoiding over-hydration. An efficient drainage system also means that the clay pebbles do not stay moist for too long. This spells bad news for water-needy plants that require frequent watering.
Unless you have access to constant irrigation, or you live in a cooler climate, this may result in wilted plants. You can also opt for drought-tolerant plants or mix your clay pebbles with other media that have a better water-holding capacity.
Clay pebbles are usually favored by small growers since these are expensive to buy in a greater capacity. Growers with large-scale hydroponic systems may have to re-think this one.
Hard but lightweight when they come out of the box, clay pebbles become much heavier once saturated. Using them in large quantities in large-scale hydroponic systems may be slightly challenging due to this reason.
This medium requires thorough cleaning – when taken right out of the bag, and before reuse. Washing clay pebbles will leave you with a red powder that can clog up your system.
Clay pebbles also need to be saturated before use. Some skip this step and let the hydroton float for the initial period until it gets saturated. These floating pebbles could get into the plumbing and disturb the system by causing blockages.
Any experienced grower knows that having a green thumb is not the be-all and end-all. Trial-and-error helped us learn how to have a successful system using clay pebbles. Here, we share with you our findings. Learn how to grow your own plants from clay pebbles, and what to look out for :
Step 1| Rinse
It may seem like common sense – but we must emphasize the importance of giving that all-important first rinse to your clay pebbles. During the manufacturing process, debris and other unwanted dust settle on the media. Even just the action of the clay pebbles rubbing against each other can produce dust.
Some manufacturers deliver the bags of clay pebbles rinsed, or even double rinsed. To be on the safer side, we recommend rinsing it over again at least 2-3 times after it is out of the bag.
You may also choose to wash them by running them under a tap until the water is clear. As mentioned, this helps to avoid problems of murky waters that clog your plumbing and system.
Step 2| Soak
This is a lesser-known step in the process – but it makes a world of a difference.
Soon after the clay pebbles are cleaned, soak them for about 6-24 hours so that they are well-saturated.
This makes sure that the roots of the plants don’t travel too far in search of water. If not controlled, this can eventually lead to wilted plants.
Step 3| Add Nutrient Solution
Once soaked, you can transfer the medium into a container. At this point, add the nutrient solution. In case you feel that the water-holding capacity of clay pebbles is unsatisfactory for the plants you plan to grow, mix in another medium.
Step 4| Transfer Seeds
Seedlings can be started in the clay itself. Remember that this is just one of the many ways to start seedlings in clay pebbles.
First, take a small starter net pot and place your soaked clay pebbles inside. Place the seeds on top and cover them with another one or two soaked clay pebbles.
Step 5| Irrigate
In case you don’t have mister fittings, you can just as easily top and bottom feed the seeds until germination occurs.
If you have gone for an ebb-and-flow hydroponic system, you can flood the container for about 2-3 minutes in an hour. This can be repeated about 16 times a day.
Tips And Tricks
In this next section, we have put together a few ideas that will maximize your experience with clay pebbles. Don’t forget to apply these tips and tricks during your next growth cycle.
Reusing Clay Pebbles
We have already discussed how clay pebbles can be used over and over again. They don’t degrade and erode easily because of their hard and sturdy form.
Simply remove the root mass that may have collected and put the clay pebbles in a container. Here, you can rinse them a few times, and apply hydrogen peroxide to sterilize the medium. Once air-dried, it is ready for its next cycle.
Starting Seeds In Another Medium
You can use other tools such as a rockwool cube to begin the germination process. Once the seedling is formed, transfer it onto the clay pebbles.
Alternatively, you may fit a cutting, such as a basil cutting, on a small cube of rockwool. Then, use the hydroton as a surrounding medium. This ensures that there is a good balance between the water-holding capacity of the rockwell, and the draining capacity of the clay pebbles.
This is another nifty idea you can utilize, especially during the germination process. This method increases the water-holding capacity of the clay pebbles.
Place the hydroton in a bag, and crush them with the help of a hammer. Ensure that the crushed pieces are not too fine, as these will get washed away into your drainage system.
Use the final product as you would use a traditional potting mix. Soak the crushed pebbles in water and plant the seeds. Once the seedlings have developed roots, you can transfer them in with bigger clay pebbles.
Frequent rinsing is absolutely necessary to have a healthy hydroponic system.
Clay pebbles absorb nutrients very well. Sometimes these nutrients build-up – which can prove to be toxic to plant growth.
Every few weeks, remove the pebbles and give them a good rinse. A tell-tale sign of toxic build-up is the formation of white residue on the clay pebbles.
As a shortcut, you can simply douse your system with a pH-neutral solution, instead of rinsing the pebbles again and again.
Once you feel that the pebbles have finished their jobs, you can put them on top of the outdoor garden soil. This has been proven to increase the soil’s organic matter content, while also providing excellent aeration.
Taking a greener approach is great. How about we make it more interesting?
Clay pebbles help you to do just that. It is technology, creativity, and sustainability – all wrapped in one.
To surmise what we have said today, clay pebbles have what it takes to allow plants to thrive. Perhaps, in the right hands, this medium is capable of growing superior quality produce. We mentioned the good and the bad of using these as your next soil alternative – and we believe the pros overshadow the cons.
Reusable and recyclable – clay pebbles ride the sustainable movement. However, we can’t ignore the drawbacks – of which one was its pricing. Although expensive, proper care of clay pebbles can prolong its life span by years and years – providing you with an assortment of plants during its lifetime.
With all the goodness of clay pebbles and this great guide to get started, your garden will be blooming in no time.