The right soil is one of the most frequently underestimated factors in plant care. Many plants don't suffer from too little water or light — but from being in the wrong substrate. As someone who keeps many tropical plants, I've tried a lot over the years. Here, I'm sharing what really works.
Why normal potting soil often isn't enough
Standard potting soil from the hardware store is too dense for most tropical houseplants and retains too much water. Aroids like Monstera, Philodendron, or Anthurium originally come from tropical rainforests, where they grow on trees or in very loose, aerated forest soil. Their roots need air — not just water. Waterlogging is the most common cause of root rot.
The most important substrate components
| Component | Properties | Good for |
|---|---|---|
| Perlite | Light, airy, hardly retains water | Drainage & aeration – almost any mix |
| Coconut coir (Coir) | Sustainable, airy, lightly moisture-retaining | Base for aroid mixes |
| Orchid bark | Coarse, very airy, slow to decompose | Epiphytes, Anthuriums, Monstera |
| Sphagnum moss | Retains a lot of moisture, antibacterial | Cuttings, propagation, terrariums |
| Lava soil / Lava granules | Mineral, airy, retains nutrients | Drainage, mineral content |
| Activated charcoal | Filters pollutants, antibacterial | Terrarium, as an additive in mixes |
| Potting soil (standard) | Nutrient-rich, but often too dense | Only as a small proportion in mixes |
My recommended mixes
General Aroid Soil (for Monstera, Philodendron, Syngonium)
This mix works reliably for most tropical plants:
- 40% Coconut coir
- 30% Perlite
- 20% Orchid bark (medium grade)
- 10% Potting soil or worm castings
💡 Tip: Ready-made aroid soil from specialized stores is a convenient alternative — make sure it contains coarse components and isn't too fine.
For Anthuriums & demanding Aroids
Anthuriums are epiphytes and need a particularly airy substrate:
- 30% Orchid bark (coarse)
- 30% Perlite
- 20% Sphagnum moss
- 10% Coconut coir
- 10% Lava granules
For Cuttings & Propagation
For rooting, we need moisture but no nutrients — the roots should actively seek water:
- 100% Perlite or
- 100% moistened Sphagnum moss
Recognizing the right substrate
A good aroid substrate can be recognized by three things: It dries out evenly within 7–10 days (not too fast, not too slow), it feels loose after watering and doesn't form a solid mass, and water drains quickly through the drainage holes when watering.
When to repot and change substrate?
Every 1–2 years in spring is a good rhythm. Signs that it's time: roots are growing out of the holes, the soil dries out very quickly or, conversely, doesn't dry out at all, or the substrate has become compacted into a solid mass. Always use fresh substrate when repotting — discard old, compacted substrate.
Common mistakes
Too much peat
Many potting soils contain a lot of peat — it initially retains water well but becomes water-repellent after drying out and compacts over time. It's better to choose peat-free or peat-reduced soils.
Pot without drainage holes
The best substrate is useless if the water cannot drain. Every pot needs drainage holes — and no standing water in the saucer.
Repotting too often
Plants need time to establish roots. Every repotting is stressful. Only repot when absolutely necessary — not just because the plant is growing slowly for a few weeks.