- Understand what semi-hydroponics is and why it’s becoming popular for houseplants and small-space gardening
- Learn the basics of LECA, PON, and the Kratky method
- Compare pros and cons of each method, including cost, maintenance, and plant compatibility
- Get practical tips for choosing the right system for your lifestyle and space
- Gain insight into daily care routines, tools, and troubleshooting
Introduction
Semi-hydroponics is a plant growing method that replaces traditional soil with inert materials and uses passive watering techniques. It marries the clean structure of hydroponics with the simplicity of houseplant care, making it perfect for indoor gardeners.
Compared to soil, semi-hydro setups are cleaner, discourage pests like fungus gnats, and often involve reusable growing media. These advantages have led to a surge in popularity, especially among apartment dwellers, hobbyists, and those caring for finicky plants.
In this guide, we’ll walk through three leading semi-hydro systems for indoor plants: LECA, PON, and the Kratky method.
Want a foundational overview first? Check out our complete primer on semi-hydroponic systems.
Semi-Hydroponics Basics and Why People Switch
Semi-hydroponics is a growing method using a soil-free medium combined with passive watering that provides consistent moisture and air to plant roots. It differs from full hydroponics in that it often doesn’t use pumps or complex systems—relying instead on gravity, capillary action, and container-based water reservoirs.
Why switch from soil?
- Better root oxygenation improves overall plant health.
- No wet organic material means fewer pests and reduced mold.
- Precise nutrient control with pre-mixed solutions.
- Reusable media reduces costs and waste.
- Great for small spaces—dual-purpose as décor and greenery.
Popular applications
- Houseplants like Monstera and philodendrons
- Orchids and air-sensitive roots
- Compact herbs and edible window-box crops
LECA: Structure, Prepping & Benefits
LECA, or Lightweight Expanded Clay Aggregate, is a popular passive growing medium that looks like small, porous clay balls. They hold moisture while allowing air to circulate around roots—excellent for tropical houseplants and orchids.
Initial Prep
- Rinse LECA thoroughly to remove clay dust
- Soak overnight to saturate the porous clay
- Optional: sterilize with boiling water or hydrogen peroxide rinse
Setup
- Use a clear nursery pot inside a cachepot with a reservoir
- LECA holds moisture; water wicks upward to roots
- Add diluted fertilizer to the reservoir monthly
Pros
- Reusable and cost-effective over time
- Promotes visible root growth
- Widely available at garden or aquarium stores
Challenges
- LECA contains no nutrients, so supplements are essential
- Requires monitoring water level regularly
- Salt buildup over time if not flushed
PON and Other Mineral Mixes: Ingredients and Built-In Nutrients
PON, like Lechuza-Pon, consists of mineral-based particles such as pumice, zeolite, and lava rock. Many versions include slow-release fertilizer, offering a more hands-off experience than LECA.
What’s inside PON?
- Pumice: improves drainage and aeration
- Zeolite: retains nutrients for steady feeding
- Lava rock: adds weight and structure
- Slow-release fertilizers: feed your plant over time
Advantages
- No rinsing or soaking—ready to use right out of the bag
- Heavy and stable: ideal for top-heavy plants
- Built-in nutrients: simplifies setup
How it compares to LECA
- PON needs watering less often due to better water retention
- Initial cost is higher, but offset by low maintenance
Alternative mineral mixes
Try akadama (used in bonsai), coarse perlite mixes, or custom mineral substrates. These offer similar benefits but may require fertilizer supplementation and more frequent watering.
The Kratky Method and Passive Reservoirs Explained
The Kratky method is a form of hydroponics that requires no electricity, no pumps, and minimal effort. It’s perfect for growing leafy greens and herbs in a kitchen or window shelf.
How it works
- Place a net pot with a seedling above a container filled with nutrient water
- As the plant drinks water, the level drops, creating an air gap for roots to breathe
Great for:
- Lettuce
- Basil and cilantro
- Spinach and microgreens
Setups to try:
- Mason jar + net cup + liquid nutrients
- Plastic bin with drilled holes for larger trays
Pros
- No moving parts or refills needed during a grow cycle
- Fast results and easy cleanup
Limitations
- Not ideal for houseplants or long-term use
- May develop algae if not covered
Pros & Cons: Cost, Weight, Maintenance, Plant Suitability
| Method | Cost | Weight | Maintenance | Beginners | Reusability | Best Plants | Issues |
|---|---|---|---|---|---|---|---|
| LECA | Low | Light | Moderate | Easy | High | Houseplants, orchids | Salt build-up |
| PON | Medium | Heavy | Low | Very Easy | Medium | Tall, top-heavy plants | Pricey |
| Kratky | Very Low | Light | Very Low | Very Easy | Single Use | Herbs, lettuce | Algae, limited use |
How to Choose the Right Medium and Pot for Your Plant
Match your system to your plant and your routine:
Plant Types
- Tropicals and philodendrons: LECA or PON
- Orchids & epiphytes: PON for stability
- Herbs/edibles: Kratky or LECA with nutrients
Lifestyle Considerations
- Travel frequently? PON retains water longer
- Want minimal intervention? Kratky is ideal
Pot Types
- Clear pots for root visibility and early detection
- Self-watering cachepots to regulate moisture
- Net cups or mesh for Kratky systems
Care Routines: Watering, Feeding and Monitoring for Each System
LECA
- Maintain water at ~1/4 reservoir height
- Flush pots monthly to remove salt buildup
- Add diluted liquid fertilizer every 2–3 weeks
PON
- Water conservatively; media retains moisture
- Replace fertilizer pellets every 6–8 months
Kratky
- Mix nutrient water once per cycle
- Keep container light-blocked to prevent algae
Tools for Success
- TDS (Total Dissolved Solids) meter
- pH test strips
- Root-safe disinfectant for flushing containers
Conclusion & Beginner Recommendations
Each system offers unique benefits—LECA is reusable and visible, PON is stable and self-sufficient, and Kratky is fast and nearly hands-off. Choose the method that matches your plant’s needs and your lifestyle.
For beginners, we recommend starting with LECA or PON for foliage houseplants and Kratky for quick-payoff herbs.
Start with just one plant to practice the system before expanding. Every plant and home environment is different—embrace the experiment!
Want more setup photos and beginner potting tips? Visit our complete guide to soil-less systems.
