Growing houseplants without traditional soil, known as semi-hydroponics, is becoming popular for its simplified care routine and reduced risk of common issues like root rot. This method relies on an inert medium, most commonly Lightweight Expanded Clay Aggregate (LECA), to anchor the plant and wick moisture upward from a separate water reservoir. Many enthusiasts utilize affordable, readily available items, with containers from IKEA being a favorite choice for creating functional semi-hydroponic setups. Understanding the science behind LECA and the specific requirements of this system allows you to successfully transition your plants into a cleaner, more controlled growing environment.
Understanding LECA and Semi-Hydroponics
Semi-hydroponics is a cultivation method where a plant is supported by an inert substrate, drawing water and nutrients from a non-circulating reservoir below. The medium used is LECA, which consists of natural clay fired at extremely high temperatures. This intense heating causes the clay to expand, resulting in lightweight, highly porous spheres with a stable internal structure.
LECA’s primary function is to act as a wick, drawing the nutrient solution up from the reservoir through capillary action. Its porous nature ensures that while the bottom layer remains moist, the rest of the root zone retains high air pockets, promoting superior root aeration. This continuous supply of water and oxygen is effective at preventing the root rot commonly caused by a lack of air in overly saturated soil. Because LECA is inorganic and does not decompose, it remains a stable and reusable medium that resists common soil-borne pests like fungus gnats.
Identifying the Best IKEA Containers
Successfully using LECA requires a two-part container system to separate the plant’s roots from constant submersion while maintaining the necessary water reservoir. The ideal setup involves an inner pot with drainage holes to hold the LECA and the plant, and an outer, watertight container, often called a cachepot, to hold the nutrient solution. IKEA containers are often repurposed for this due to their availability in various materials and sizes that fit together well.
For the outer reservoir, basic glass containers or ceramic planters without drainage holes are excellent choices, as they allow for easy visual monitoring of the water level. Alternatively, some of IKEA’s simple plastic storage bins or basic plastic plant pots can function as the outer container. The inner pot must be slightly smaller, with multiple holes in the base and sides to facilitate maximum water wicking and gas exchange. Many users opt for inexpensive plastic planting pots, which can be easily drilled or modified to increase the number of drainage holes. Metal containers should be avoided, as they can cause the nutrient solution to become too cold, potentially damaging sensitive roots.
Preparing the LECA and Plant Transfer
Before a plant can be transferred, the LECA must be pre-treated to remove fine clay dust and stabilize its initial chemical properties. Begin by rinsing the clay balls thoroughly under running water until the runoff is completely clear, which eliminates the fine clay dust that can clog the system and impede wicking. Following the rinse, the LECA should be soaked in clean water for at least 24 to 48 hours to fully saturate the porous structure and leach out any residual salts or minerals from the manufacturing process.
The plant itself requires meticulous preparation, as any residual organic soil left on the roots will decompose in the constantly moist LECA environment, leading to root decay. Carefully remove the plant from its soil and gently rinse the entire root ball under lukewarm water, using your fingers to dislodge every particle of potting mix. It is sometimes necessary to trim away soil-bound fine roots, as the plant will develop new, thicker “water roots” adapted to the semi-hydroponic environment. Once clean, place a small layer of pre-soaked LECA in the inner pot, position the plant so its old root flare sits just above where the water reservoir will be, and then fill the remaining space with LECA, gently tapping the pot to settle the balls around the roots for support.
Water Management and System Maintenance
Ongoing care in a LECA system centers on precise water and nutrient delivery, which is much different than watering soil-based plants. The general rule for the reservoir level is to maintain the nutrient solution at approximately one-third of the height of the inner container. This level ensures the LECA at the base is submerged to wick water upward, while the rest of the roots are kept above the water line, allowing them access to oxygen. Allowing the reservoir to completely dry out briefly between refills is recommended to further promote aeration.
Since LECA is inert and contains no nutrients, all necessary elements must be supplied through a specially formulated liquid hydroponic fertilizer, as standard soil fertilizers are insufficient. Over time, the nutrient salts will accumulate in the LECA and on the pot walls, which can lead to chemical imbalances and plant stress. To prevent this “salt buildup,” the entire system must be flushed with plain, pH-balanced water every four to six weeks. Flushing involves running a large volume of clean water through the LECA to wash away the excess salts before refilling the reservoir with a fresh nutrient solution.