Orchid Bark / Fir Bark Substrates in Terrariums (Pro’s & Cons)

Orchid bark is a fantastic naturalistic substrate for all kinds of terrariums.

It brings a host of benefits to more comprehensive mixes (like the ABG mix) or it can be used as a standalone substrate for some kinds of plants.

In this article, we’ll cover when and how to use orchid bark in a terrarium, along with which kinds are best for different setups.

Let’s get to it!

What is Orchid Bark?

First things first, let’s get the awkward naming out of the way.

Orchid bark is bark for orchids, not bark from orchids. Orchids don’t have bark my dudes… we need trees for that. 

It’s actually sourced from a variety of coniferous trees. but by far the most common is fir bark

So the names are kind of interchangeable, and sometimes you’ll simply see it labelled as “terrarium bark” or “reptile bark”.

It mostly comes as chips or shavings of various sizes, but it’s used in horticulture in a variety of other ways like for mulches and dust too.

Advantages of Orchid Bark Substrate

  1. It’s a natural material, so it looks and feels authentic in a terrarium environment.
  2. The chunky nature of the bark makes it fantastic at aerating soil, resisting compaction and providing drainage in a substrate mix.
  3. Increases water retention to a degree, which it turn helps to boost ambient humidity,
  4. It’s sustainably sourced, which is always nice.
  5. Smells good!

There’s a couple of potential disadvantages that are worth noting.

  1. As an organic product, it will eventually break down. If you want a terrarium that’s going to last as long as possible without a substrate change, you might want to swap this out for a longer lasting material like coco fibre.
  2. As orchid bark breaks down it has an acidifying effect. Which isn’t inherently bad, but many plants prefer an alkaline soil. Not to worry though, this can be offset with other soil supplements if it becomes a problem.

Why Douglas Fir Bark?

Fir bark is a common choice as it breaks down much more slowly than other tree barks such as hardwoods.

Occasionally you’ll also see the likes of pine bark, redwood bark and hemlock bark, but as far as I can gather there’s not a huge amount of difference. If you prefer the smell of pine then that’s probably the only important factor to consider.

Seeing as you’ll come across douglas fir bark substrate 99% of the time, that’s what I’ll be referring to.

One fine Douglas Fir Tree

Types of Orchid Wood Chips

When you’re looking for orchid bark on the web, it’s always going to come in the form of wood chips. The size of which is going to be called the “grade”.

The choice of grade you go for should be determined by the size of your terrarium and whether you’re using it as part of a mix or a standalone substrate. Let’s look a little closer.

Fine Grade Orchid Bark

I really like the fine grade orchid bark, especially for smaller terrariums. 

The chunks are still large enough to provide all of their structural benefits, but small enough that you can fit more than half a dozen into a jar terrarium.

If you’re making up a custom mix and need some orchid bark to make up a portion of it – this is your best bet. It’s also better for younger and smaller plants in general.

Here’s a great bag on Etsy (1/4 inch chunks).

Medium Grade and Coarse Orchid Bark

As you might imagine, these are just larger chunks. 

They tend to be best when you don’t want orchid bark to be just part of a mix, but rather you need it to be the mix.

A largely coarse orchid bark substrate will drain and dry very quickly.

Some plants grow well in a super chunky, well aerated mix (mostly epiphytes like Bromeliads and Dischidia). Or particularly large tropical plants like Aroids can fare well in chunky orchid mixes too.

Grab a portion of coarse orchid bark here on Etsy too (3/4 inch chunks).

Orchid Mix/ Orchid Potting Mix 

As with all forms of potting mix, orchid potting mix is quite literally a mixed bag.

Often the bark itself is blended with other fibrous materials like coco fibres, seramis (a kind of clay) and often perlite.

They can be great for use in terrariums, but it’s always important to check the label!

Wrapping Up

What’s your experience with using orchid bark in terrariums?

Have you tried any other barks beyond fir bark with greater success?

Let us know in the comments.

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