- The basics of semi-hydroponics and how soilless systems work
- Which media (LECA, PON, etc.) is right for your plants
- How to set up a simple semi-hydroponic system from scratch
- How to mix and measure nutrient solutions using EC and pH
- Steps for converting your soil-grown houseplants to semi-hydro setups
- Maintenance tips for flushing, cleaning, and reusing your media
- Common issues in passive hydro and how to fix them
Introduction to Semi-Hydroponics and Why Use Inert Media
Semi-hydroponics is a method of growing plants using an inert, inorganic medium instead of traditional soil. In these passive systems, water and nutrients are delivered through capillary wicking or bottom reservoirs, providing consistent moisture and oxygen without the mess of soil.
Why choose soilless growing? For one, it significantly reduces the risk of pests and soil-borne diseases. It also increases oxygen availability at the root zone, encouraging stronger root systems. Moreover, nutrient levels and moisture are easier to monitor and control—ideal for beginners and picky houseplants alike.
Learn more about key differences between passive hydroponic systems in our guide: Semi-Hydroponics 101: LECA, PON & Kratky Compared.
Choosing the Right Medium: LECA, PON, and Other Soilless Options
There are several media options used in semi-hydroponics, each with its own characteristics. Understanding their pros and cons helps you choose what’s best for your plant collection.
Common Inert Media
- LECA (Lightweight Expanded Clay Aggregate): Porous, clay balls that provide excellent aeration and drainage while wicking moisture from a reservoir.
- PON: A mineral-based blend often containing pumice, zeolite, and lava rock. It retains moisture and nutrients more efficiently than LECA.
- Other Options: Perlite, vermiculite, and rock wool are also sometimes used, though less common in passive hydro setups.
LECA vs PON Comparison
| Feature | LECA | PON |
|---|---|---|
| Airflow/Oxygenation | Excellent | Moderate |
| Water/Nutrient Retention | Low to Moderate | High |
| Reuse & Cleaning | Easy | Moderate |
| Cost | Affordable | More Expensive |
| Best For | Pothos, Philodendron | Orchids, Hoya, Anthuriums |
Still deciding between LECA and PON? Dive deeper in our LECA vs PON Pros, Cons & Use Cases guide.
Essential Gear: Setting Up a Semi-Hydroponic System
Setting up your own semi-hydroponic grow system is easy with just a few components:
What You’ll Need
- Net pots or nursery pots with drainage
- Outer cover or cachepot to hold water (serves as reservoir)
- LECA, PON, or other chosen inert medium
- Optional: humidity domes, grow lights, wicking cords for additional moisture control
Common Passive System Types
- Wicking Systems: Use absorbent cords pulling water from a reservoir up to the roots.
- Self-Watering Containers: A pot-within-a-pot system where the inner pot holds roots and outer pot stores nutrient water.
Explore more design options in our guide on Wicking & Passive Hydro Planters.
Mixing Nutrient Solutions: EC & pH Basics for Semi-Hydro Success
Unlike soil, inert media doesn’t provide nutrients—so you’ll need to add them carefully.
Plant Nutrient Essentials
Plants require macronutrients (N, P, K) and a suite of micronutrients to thrive. Maintaining accurate pH and EC levels ensures your plants can absorb them effectively.
| Parameter | Target Range | Why It Matters |
|---|---|---|
| EC (Electrical Conductivity) | 0.5–1.2 ms/cm | Indicates nutrient concentration |
| pH | 5.5–6.5 | Affects nutrient uptake efficiency |
Tips for Mixing & Measuring Nutrients
- Use a digital pH meter and EC meter for accuracy
- Premixed hydro nutrient solutions are great for beginners
- Feed your system every 1–2 weeks and flush regularly
Create and manage feeding plans using our guide on Feeding Schedules for Semi-Hydro.
Converting Soil-Grown Plants to Semi-Hydro
Most houseplants adapt well to passive hydro systems with a gentle transition process. Here’s how:
Step-By-Step Conversion
- Gently remove soil from roots and rinse thoroughly
- Inspect roots, trim any rot or thin areas
- Pre-soak LECA/PON to saturate it and remove dust
- Place the plant into its new pot and add prepared medium
- Add nutrient water to the base reservoir
Handling “Transition Shock”
Signs like wilting or slowed growth are common during conversion. Keep light low, humidity high, and check roots weekly. Most plants bounce back in 2–4 weeks.
More details on this process can be found in our tutorials: Step-by-Step: Converting from Soil to LECA and Overcoming Transition Shock in Semi-Hydroponics.
Ongoing Care: Watering Methods, Flushing & Cleaning Inert Media
Watering the Right Way
- Check reservoir levels weekly
- Top off with diluted nutrient water (avoid full refill unless needed)
Flushing to Prevent Buildup
Over time, nutrient salts can accumulate in the media. Flush every 3–4 weeks with plain water:
- Remove the plant and rinse LECA/PON under running water
- Let it drain and dry for a few hours
- Add fresh nutrient solution
Cleaning and Reusing Media
- Soak in 1:10 bleach solution or hydrogen peroxide for 2–4 hours
- Rinse thoroughly and let air dry before reuse
Read our full cleaning protocol: Cleaning & Reusing LECA and PON.
Troubleshooting Common Semi-Hydro Problems
Recognizing Warning Signs
- Algae: Forms on exposed LECA or pot walls—fix by covering surface or limiting light
- Root Rot: Usually from over-submersion or stagnant water—improve oxygen or flush more often
- Salt Buildup: Appears as white crust on media—flush regularly
Healthy Plant Signs
- White, firm roots
- Faster new growth
- Stable turgidity and leaf color
Get help solving more issues here: Troubleshooting Common Semi-Hydro Problems.
Bonus: Specific Plant Considerations
Great Plants for Semi-Hydro Beginners
- Pothos
- Peace Lily
- Hoya
- Orchids
Check out our specialized care guide for popular species: Top Plants for LECA Semi-Hydro and Semi-Hydro Care for Orchids & Epiphytes.
Conclusion & Next Steps
Semi-hydroponic systems offer a cleaner, more efficient way to care for houseplants. Whether you’re growing hoyas or philodendrons, using LECA or PON lets you control your plant’s environment more precisely for stronger growth and fewer problems.
Ready to give it a try? Start by converting one plant and experiment with the process—it’s easier than you think!
Need more guidance? Explore our library on nutrient mixing, planter setups, and troubleshooting common issues.
How to Build a Semi-Hydro Conversion Tracker in Make.com
- Trigger Module: Schedule trigger – runs weekly to update status check
- Google Sheets Module: Create a sheet titled “Plant Semi-Hydro Tracker” with columns: Plant Name, Date Converted, Medium, Last Fed, EC Level, pH Level
- Text Parser Module: Optional module if inputs are emailed or filled via a form
- Notification Module: Send yourself an email/slack message when a plant needs flushing or feeding (flag by “Last Fed” date)
This Make.com scenario simplifies the ongoing care and reminders involved in passive hydro setups—perfect for plant lovers managing multiple conversions.
