Why do I like that mix?

To say, without exaggeration: I have mixed the BEST EVER medium for Hoya plants… for my particular environment (important!). I have been using it for over a year now. With a couple of tweaks, it became my Go-To Mix, from a cutting to a mature blooming plant.

Main qualities of the mix: airy, fast-drying, it holds just enough moisture, extremely slow to degrade. Does not affect the PH of the soil. Does not suffocate roots as coco chips and does not dry out roots as it happens with Leca or PON-alike substrate when left without watering for too long. No critters that love/live/eats the bark (but it is not 100% pest resistant).

Links to the components and supplies are provided at the end of the post.

Hoya Megalaster with bare roots wrapped around tree fern

I am not going to describe other options of mixes here. I do use other variants of soil mixes in different circumstances, but let me focus on the BEST (IMHO) soil recipe. The Mix has/had its flaws but was easy to fix, and changes improved the Mix tremendously.

The base of my preferred Mix for hoya is a New Zealand Tree Fern. I was trying to grow plants in 100% Tree Fern. It did not work out as I expected. I have several mature Hoyas in pure Fernwood in Self-watering Lechuza pots. The roots of those Hoyas are enormous. But I have to be careful with the amount of water to add to the reservoir.

Hoya Caudata Sumatra with bare roots

What is a Tree Fern?

From the seller “Tree fern is a natural, organic, long-lasting substrate, widely used as Epiphyte growing medium, as a terrarium/vivarium substrate. It locks in moisture without oversaturation. It does not dry out as fast as Orchid Bark.”

The benefit of not drying fast should be kept in mind because it can become a disadvantage while using it in an environment with higher relative humidity. Most of the plants in my collection (including stock plants) are in Ikea Cabinets, terrariums, and Grow Tent with RH ~80% and temperatures over 80F.

Tree Fern Bag 40 Liters

How did I come to use Tree Fern for Hoyas?

The questions were:

  • What could be the Perfect Grow Medium for most Hoyas? With no trees involved.
  • Can I provide a hoya plant with potting soil that will make it healthy, happy, fast-growing, and blooming (eventually)?
  • How can I recreate a close-to-natural environment in my home? Be it a box with high humidity or a shelf near the window.
  • Also, is there a way to shorten the maintenance time without making plants struggle?
  • And how great would it be to root a hoya cutting and let it grow without changing its medium until it needs a bigger pot? Or never???
Tree Fern Substrate

Epiphytes Pros.

Who is an expert in growing epiphytes successfully? Of course, Orchid People. Their sites, blogs, and forums are the places to dig. Those guys nailed it. Many had great results using tree fern as a growing medium for orchids. I decided to give a Tree Fern a try. What do I have to lose? A $149 bag of brown twigs that I would not know what to do if the idea won’t work? 😀

After using Fernwood for several months, I wanted to find a Hoya Grower who prefers/uses tree fern because I was experiencing some, let’s say, unexpected problems. The famous Hoya Grower, Mr. Dough Chamberlain from Vermont Hoyas, mentioned in one of his videos that he switched to pure Tree Fern to grow some of his plants. That was enough for me to continue using it and forced me to think of ways to eliminate the “flaws.”

Hoya Elliptica in Lechuza pot Mini-Deltini

Drawbacks and solutions.

As I propagate hoya cuttings in boxes or terrariums with high relative humidity, the tree fern stays moist for too long in even small pots. It leads to root or stem rot for some cuttings, especially with thin stems. One of the solutions was to place the cutting on top of the soil and attach it with a plastic pin, which helped avoid stem rot.

Another thing is the price; this stuff is expensive. And often out of stock. The solution was to mix Tree Fern with something that adds aeration, helps the soil dry faster, and lowers the overall price.

The basic and cheapest option is two parts of Fernwood to one part of perlite (small size). An improved option is to substitute perlite with Lava Rock (or Pumice). It is not as cheap as perlite but does better in a mix. If feeling fancy, I add some Horticultural Charcoal, about 5%-10% of the total volume.

In other words, to two parts of Fernwood, I would add one part of whatever I currently have in my storage: Pumice, Lava Rock, or Perlite (or mix). For better Cation capacity, I add Montmorillonite Calcined Clay (Monto Clay).

An extra topping: Diatomaceous Earth. It is dusty and makes the look of the soil mix non-presentable (before the first watering). But trust me, it is worth it. Tell me again that Springtails are beneficial. I still don’t want those in my soil (sometimes I have way too many!) and no fungus gnats for a while. So, that would be my Number Zero preventative method. Most of it will wash out from the soil with time, though. I wrote a post about every method that works to prevent and get rid of all the types of pests in the soil and on the houseplants. You can read about it here: How I combat pests.

Ultimate Soil Mix for Hoya

And here we have it: THE ULTIMATE MIX FOR HOYA!

  • Four parts of Fernwood,
  • One part of Perlite (Pumice or Lava Rock, or a combination),
  • One part of Monto Clay,
  • About 1/4 to 1/3 part of Horticultural Charcoal,
  • Plus, some Diatomaceous Earth. Sprinkle generously.

Mix everything well, be careful not to breathe in the dust, and voila, best of the best! Your hoya will thank you with crazy growth and heavy root mass and blooms with a heavenly smell 😀

You can read more about the feed and fertilizers I use in this post: Fertilizers and Supplements for Plants.

Growing Medium for Hoya Plants

Where to buy Tree Fern?

I buy Fernwood from Amazon; I believe the price is more or less the same at different online stores unless you are in New Zealand. There is an option to order wholesale, which is cheaper for the unit, but the shipping cost may be about 50% of the total price of the total amount. And the volume could be more than one needs.

There can be some large chunks or very long twigs in the bag of Tree Fern, which are not suitable for a 3 oz plastic cup or a small pot. I either keep them separately and use them for larger pots/plants or cut them with scissors.

Hoya Elliptica Foliage

Thank you!

Happy growing 💚