Tree Fern Soil Mix (Once More)

Briefly

• What It’s About: Tree fern-based soil mix for houseplants.
• Why Tree Fern?: Great aeration, moisture retention, and long-lasting.
• Mix Variations:
  • Cuttings: 100% tree fern.
  • Small Pots (2–3 inches): 2–3 parts tree fern, 1 part Pon or perlite.
  • Medium to Large Pots: 50% tree fern, 50% pumice/lava rock/Monto clay/zeolite.
• Key Additives: Diatomaceous earth for pest control, mostly.
• Tips for Success: Adjust the mix for your conditions, observe your plants, and experiment until you find what works.

Tree fern has become a favorite growing media for Hoyas and other houseplants. Its balance of moisture retention and aeration makes it almost foolproof—though I’ve certainly had my share of experiments before finding what works for me. The mix can vary depending on the plant, pot size, and environment, and I’ll walk you through how I customize it and why each ingredient earns its place.

Why Tree Fern?

Tree fern is a natural, sustainable material that offers:

• Great Aeration: It helps prevent root rot by letting excess moisture drain. (That said, yes, I can still overwater!)
• Moisture Retention: Holds enough water to keep roots hydrated without getting soggy.
• Longevity: It breaks down slowly, so you won’t need to replace it often.

For Cuttings in Tiny Pots or Cups

• Proportions: 100% tree fern.
• Why? Pure tree fern provides the perfect balance for young roots to establish themselves.
• Setup: I keep propagations under a humidity dome to maintain moisture, and the first watering always includes a root enhancer. Sometimes, the cutting has aerial roots or was pre-rooted in water or damp perlite before being placed in the tree fern.

For Small Pots (2–3 inches)

• Proportions: 2–3 parts tree fern, 1 part Pon (or perlite).
• Why Pon?
  • Adds mineral stability and enhances drainage.
  • Holds nutrients and releases them over time.

I started using Lechuza Pon it after watching Mona (@Planttherapy1860 on YouTube). I have a lot of it left after buying self-watering Lechuza pots, but not using the pon. The size of the particles are smaller that Pumice and Lava Rock I purchase from Bonsai Jacks. Thank you, Mona!

• Alternative: Perlite
  • Lightweight, improves drainage, and prevents compaction (not that tree fern compacts much).
  • Small perlite particles work best for young roots.

 For Medium to Large Pots

• Proportions: 50% tree fern, 50% pumice, lava rock, Monto clay (for Hoyas), and zeolite.
• Why? This mix works whether the pot is self-watering or not and keeps the soil airy yet moisture-retentive for plants in various conditions.
• Ingredient Benefits:
• Pumice: Improves aeration and adds weight—great for stabilizing plants on trellises or moss poles.
• Lava Rock: Boosts drainage and creates micro-pockets for beneficial bacteria.
• Monto Clay: Holds water and nutrients while adding acidity (great for Hoyas). I leave it out for plants like Monsteras or Syngoniums.
• Zeolite: Enhances soil fertility by absorbing and slowly releasing nutrients.

The Not-So-Secret Ingredient: Diatomaceous Earth (DE)

When I remember (and have it), I add DE for these reasons:

• Pest Control: Deters pests like fungus gnats—though the soil needs to dry out for DE to work.
• Water Retention: Absorbs moisture and releases it gradually.
• Non-Toxic: Safe, but wear a mask to avoid inhaling the dust!

Tips for Success

1. Adjust the mix for your environment, watering habits, and plant needs.
2. Watch the tree fern—it changes color when dry, so use that as a watering cue.
3. Experiment and take notes. Over time, you’ll find what works best.

Here are photos of some plants, in 100% tree fern fiber and in the mix.

For those of you who stayed until the end—first of all, thank you!

Secondly, if you have a business (big or small) and are located in the USA, I highly recommend checking out Acadian Supply. They offer tree fern at a much lower price than you’ll find on Amazon or eBay. There’s no minimum order requirement. It’s a great way to save while stocking up on quality materials!