Gardeners new to orchid growing soon realize that healthy orchids don’t grow in regular potting soil, but the choices available in orchid potting media can be confusing. Many orchid cultivars can grow in a one-ingredient medium, and making your own custom orchid mix is fun when you get to know the needs of your plant. Many high quality orchid growing media have similar benefits, so cost, availability, and appearance may help you narrow down your choice.
Brick chunks add weight and stability to heavy orchid pots. Brick is somewhat water retentive, increasing humidity for your orchids.
Cobblestone works well as an anchor in the bottom half of an orchid pot. The small, uneven rocks are heavy, which helps top-heavy orchids like dedrobiums stay upright. Cobblestone will not retain water, so help increase drainage properties of your orchid mix.
You can use coconut coir alone, or as part of a custom orchid mix. The long fibers absorb moisture, but also drain quickly, so orchid roots experience moist but not soggy growing conditions.
Coconut Husk Chips
A renewable resource, coconut chips come in different sizes to meet your needs as a standalone growing medium or a potting mix additive. The chips decompose slowly, ensuring maximum air circulation for orchid roots. Orchid growers can also look for coco husk fiber plaques, which provide an excellent substrate for growing orchids on mounts.
Anyone with a vintage bottle of wine is familiar with the watertight qualities of cork. You can mix water-shedding cork with water-absorbing sphagnum moss or shredded bark for an ideal orchid mix. The larger cork chips offer many crevices for orchid roots to explore.
Expanded Clay Aggregate
If you’ve wondered about those rocks in your orchid pot that look like Cocoa Puffs cereal, you probably purchased a plant grown in an expanded clay aggregate like Aliflor or Hydroton Clay Pebbles.
Unlike regular rocks, these ceramic pebbles are porous and lightweight, and are neither acidic nor alkaline. You can use them alone, mix them with other growing media, or use them as a mulch on all of your orchids to give them a uniform appearance.
You will commonly see this inorganic growing medium used in orchids imported from Hawaii. Like other rock growing media, lava rock won’t break down, and is a good potting mix amendment for orchids that don’t like to have their roots disturbed. Lava rock retains water, increasing humidity for your orchids.
Perlite, also known as sponge rock, is actually the end result of volcanic glass exposed to high heat. Although perlite doesn’t contribute any nutrients to orchid plants, the substance has excellent water retention and aeration properties.
Pumice has many fans for its polishing potential on rough skin, but this volcanic rock is also a lightweight inorganic growing medium for your orchids. The rock is highly porous, holding up to 50% of its weight in water.
The cotton-like fibers of chalk and basalt will never break down in your orchid potting mix. Balance the alkalinity of rock wool cubes with an organic ingredient like bark or peat moss.
Shredded bark from trees like fir, cedar, and cypress acidifies your orchid mix as it breaks down. Bark is also favored for its natural look and pleasant fragrance. Orchids growing in a bark medium may need repotting once a year.
Weed and pathogen-free sphagnum moss maintains a moist environment for your orchid roots without becoming soggy. Often sold in compressed bricks, you must re-hydrate the moss and pack it loosely into your orchid pot for best results.
Orchids that like periods of dryness may thrive when grown in a Styrofoam medium. Simple Styrofoam peanuts can work as a growing medium, or you can buy special Styrofoam pellets like Aerolite produced specifically for epiphytic plants.
Vermiculite combines well with sphagnum moss to create a light, moisture retentive orchid mix.
The mineral is usually sold in gravel-sized particles.