Tools & Techniques  |  September 30, 2022

How to Use Aeration Stones

 Aeration stones used for direct potting.


What are Aeration Stones?

Aeration Stones (also known as Lightweight Expanded Clay Aggregate or LECA™) are made from clay that is heat-treated in a rotary kiln to expand and harden. During the heating process, gasses within the clay expand to create a honeycomb-like structure within each stone. The stones function by absorbing and retaining water, which is then slowly released as the area around them becomes dry.

These lightweight clay stones are an invaluable material for your plant’s root health. There are many horticultural uses of LECA, from using it as a hydroponic growing medium to house plant drainage material. They provide great drainage with increased air supply to the root zone which means healthier, happier plants.

Ready to dive into the world of Aeration Stones? Below you will find instructions for their various uses in the cultivation and care of houseplants.


The Benefits of Using Aeration Stones for Drainage

PRO TIP: Aeration stones are a highly sustainable horticultural material in that they are reusable and durable with a consistent plant-happy pH of ~7. Simply rinse your aeration stones between uses and repurpose them again and again.

Whether you’re potting your plant into a container with or without a drainage hole, adding aeration stones is a beneficial strategy to ensure root health and protection (however, if you’re using a container without a drainage hole, aeration stones are definitely a must). The stones help prevent water buildup in the bottom of the planter and keep sensitive roots distanced from standing water. Additionally, as the soil begins to dry, it will draw water from the clay which can help extend the length of time between waterings. When potting a plant, simply fill the bottom of your pot with aeration stones before adding in soil and the plant. The clay will expand and retain excess water which will help prevent overly moist soil and roots which can lead to root rot.

The more stones you place in the bottom of the container, the bigger the buffer you have for excess water. You’ll want to increase the depth of the aeration stone layer depending on the size of the pot to maintain enough room for soil and the root mass of the plant.  

We suggest a minimum of 1" depth in the bottom of a 4"-6" diameter planter. For a diameter of 8"-14" you would want at least a 2" layer of stone. For larger pots add a buffer of 4"-6" if possible.

How to Use Aeration Stones as a Potting Medium

Aeration stones can also be dispersed within a potting mix to help decrease water retention by creating air and water flow within the pot. They make a great choice when assembling your own potting mix at home, or they can be added to an existing mix that holds too much moisture for certain plant varieties. This method works well for aroids like Alocasias, Philodendrons, and Monsteras. Some plant species can even be grown in a potting medium of LECA exclusively, but since the aeration stones do not have any nutrients, these plants would require fertilizing on a regular basis.

When using aeration stones as a stand-alone growing medium (also known as semi-hydroponic growing) there are 3 basic steps you need to follow:

Step 1: Prepare your aeration stones. Rinse the aeration stones with water to remove any clay dust, then soak the stones for 10-24 hours until they are fully saturated and none float to the surface. (This step can be skipped, but the pH may be affected and it may require additional waterings to establish the plant.)

Step 2: Transfer your plant. Remove your plant from its pot and gently massage the dirt from the roots of your plant. Run the root ball under lukewarm water to remove any soil and small particles. Add 1"-2" of aeration stones to the new container you wish to use (we prefer glass so we can see roots develop, but plastic or glazed ceramic also work well). Place your plant in the container and fill the remaining space with saturated aeration stones. Fill the container with lukewarm water to just above the line of aeration stones.

Step 3: Water and fertilize. When you see the stones have dried out and only a small amount of water remains in the vessel, refill the planter with water and consider adding a diluted water soluble fertilizer. Aeration stones are sterile and contain no nutrients, so it’s important to add hydroponic fertilizer to your water to provide your plants with the nourishment they need to grow.

How to Use Aeration Stones for Plant Propagation

Aeration stones are a great tool for propagation. The stones offer structural support for plant cuttings and as they contain no nutrients, are perfectly safe for all kinds of water propagation. We also like that root development can be easily monitored and the moisture can be more easily controlled. Simply fill a clean, clear vessel with rinsed aeration stones and fill with water. Gently place the plant cutting within the vessel while shifting the aeration stones to provide support. Keep the stem and nodes beneath the water line and the foliage above water. You can also consider using rooting powder when propagating to increase the speed and overall health of your propagation’s growth.

Using Aeration Stones to Create a Humidity Tray

This simple method effectively increases humidity and is especially useful for groupings of plants. To make a humidity tray at home, start by sourcing a tray larger than the circumference of the pot opening. Our Fiberglass Saucers are a great solution. Line the tray with aeration stones and place the planter on top of the stones which will keep the pot elevated. Fill the tray with water until the water is almost touching the bottom of your planter. However, don’t let the plant sit in water as the purpose of this setup is not to bottom water the plant. As the water evaporates, it will increase the moisture in the air around your plant. Refill the tray as needed to help maintain a humid environment for your plant. Pro tip: This is an especially great option for plants that live near radiators or AC units which dry out the air.

Using Aeration Stones in Self Watering Planters

At Greenery Unlimited, we’re all about making the plant parenthood life work for you. That’s why we created a line of beautiful self watering planters designed to help your plants thrive (with less effort on your part).

Each of our self watering planters comes with a packet of small aeration stones. To use them, simply pop in the plastic insert and line the bottom of your planter before adding soil and your plant. The combination of using sub-irrigation and aeration stones will help ensure healthier root development and prevent common issues like root rot and overwatering. Happy planting!


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