Orchid Bark - What it Actually is & Why it's Used
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Orchid bark in potting mix is not wood or bark from Orchid plants, it is normally coarse and contains “chunky” or large chips made from Pine or Fir tree bark and is used in potting mix for Orchid plants to provide aeration, drainage, and a solid base for the Orchid’s roots to grow. The bark chips from these plants help to mimic the natural environment that the Orchid’s roots use to secure it to a tree or in the ground so the plant can stabilize and grow.
Orchids are epiphytes, meaning they grow on other plants and use the plant for support vs. being parasitic and stealing nutrients just like Hoya, Peperomia, and Anthurium. These large chunks replicate the open space that allows the roots to stabilize while getting air and is part of the “structure” of the potting mix.
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Orchid Bark and Potting Mix Structure
Structure in potting mix and soil is how the ingredients are combined to create air pockets, allow for drainage, the ability to retain enough moisture, and prevent the mix from getting compacted.
Chunky mixes with “orchid bark” are considered a larger structure in that the particles and pieces like bark chunks provide more room for roots to move through, air to get trapped, and moisture to drain. In nature, the earth provides a natural drainage system so plants don’t get overwatered and can thrive. Pots for plants with regular soil lack this natural drainage, so climbing plants like Orchids need the chunks in the potting mix to survive, which is one of the reasons Orchids are a moderate to advanced level houseplant.
By having a larger structure, Orchid bark potting mixes provide the perfect environment for plants like Orchids that thrive by getting moisture when they need it, whose roots need to grip into open spaces to hold their position, and have room to expand and breathe.
The Benefits of Orchid Bark
There are three benefits to Orchid bark in potting mix including:
Drainage
Aeration
Moisture retention
Drainage
The chunky pieces of Fir and Pine tree bark help to keep the potting mix from compacting which allows excess water to drain through the potting mix so root systems do not get waterlogged. When potting mix is waterlogged it can drown the plants which cause the leaves to wilt or discolor, or cause a disease known as root rot. Root rot is where the roots begin rotting which kills the plant.
Aeration
Once the water has left the potting mix in the container, the chunky mixes hold the dirt in place creating air pockets which are sometimes called soil pores. The air pockets allow the roots to breathe as well as expand around the container. If roots get compacted they cannot expand and become “root bound” which will stunt the plant’s growth and cause it to die.
Fun fact: Roots need oxygen to breathe and grow in a cycle similar to how we breathe. Oxygen can only make it so far down into the ground before it is too compacted, so roots tend to grow higher towards the surface where they can access oxygen in the soil pores.
Moisture Retention
Tree bark naturally absorbs and retains moisture and nutrients which it can release back into the container. This helps to make sure the potted plants are able to get moisture and nutrition on an as needed basis which is vital for more advanced level plants like orchids.
Orchid bark potting mix is not made from actual orchid bark, it is a reference to a potting mix designed specifically for plants like Orchids that need specific amounts of air pockets, drainage, and moisture retention to grow. Because of orchid’s popularity, chunky potting mixes made with larger particles like Fir and Pine tree chunks get the nickname Orchid Bark.
