Skip to content

Soil for orchids – what types of substrate are suitable for the tropical flowers?

Everyone knows the typical orchid substrate made of large pieces of bark, which is considered ideal for cultivation of exotic beauties. It retains water, which prevents the moisture-loving plant from drying out, and at the same time, due to its coarse texture, guarantees sufficient air circulation for the aerial roots. Moreover, it is loose and does not prevent the rather weak roots from growing. And although this type of substrate is the most common, it is far from the only one that is suitable. What soil is suitable for orchids alternatively or as an additive, we list below.

The ideal substrate has these properties

What soil for orchids - alternatives and additives for mixing orchid substrate

For orchid substrate to be truly optimal for these special plants, it must:

  • be able to retain adequate amounts of moisture
  • be able to absorb nutrients and release them to the plant
  • guarantee air circulation through a loose consistency to allow for a healthy exchange of oxygen
  • Be loose enough for roots to grow through, as they cannot penetrate hard substrate.

Conventional potting soil is suitable, but only as an admixture or in combination with coarse sand (see below).

Use coconut fibers as orchid substrate

What soil for orchids - coconut fibers are permeable and retain moisture.

The name already gives away what we are talking about here. The fibers of the coconuts are crushed and then resemble normal potting soil with the subtle difference that here too, despite the finer consistency, the water can drain off wonderfully and the air can circulate. At the same time, however, its denser texture ensures proper stability for the plant more quickly, while the nutrients promote healthy and strong roots. Coconut fiber as soil for orchids are also able to retain moisture – but just not too much.

Instead of soil for orchids: Water culture with clay granules or expanded clay.

Expanded clay and clay granules as water reservoirs for water culture

The so-called hydroponics is becoming increasingly popular among orchid owners, because it always provides the plants with the right amount of moisture and since you should always use a water level indicator, you will always know exactly when it is time for a new watering. Water culture works best entirely without substrate and in the glass . However, many choose to alternatively put the orchids in granules of clay, as this substrate provides more support and stability.

Charcoal as a substrate for epiphytic plants

Charcoal – not to be confused with coal and in no way grilled! – is ideal to add to other orchid substrate, but not as a sole substrate substitute, as it is not able to retain moisture. However, it does have other valuable properties. Firstly, it neutralizes odors, which is without question very useful for houseplants. Secondly, the material has a pH-balancing effect, which prevents root burns, as well as antibacterial properties and has a healing effect, as it absorbs pollutants.

In countries with very high humidity, charcoal is also used exclusively as soil for orchids, precisely because it does not retain additional moisture, which in these regions could quickly lead to root rot.

What soil for orchids – Crushed cocoa shells.

Mixing cocoa shells into the substrate as a long-term fertilizer

The shells are a waste product resulting from the production of chocolate, and therefore a purely natural product. A particularly important advantage is, the nutrients contained therein gradually released over the course of several years, as the material decomposes very slowly. This is also the reason why people like to fertilize with it. Good air circulation is also guaranteed, since it is a coarse substrate. Perfect, therefore, to mix it into the soil for orchids.

Shredded bark as an orchid substrate.

This is exactly the substrate as you know it from orchids. Bark is crushed and used in more or less large pieces as soil for orchids. Optimal for this purpose is the bark of pine and pine, but also eucalyptus, and usually you can find them in stores without any problems. They not only have the wonderful property in itself to retain moisture, but also slightly acidify during decomposition, which orchids simply love. They also keep the temperature fairly constant. A small disadvantage compared to cocoa shells is that the bark decomposes faster and needs to be replaced. But even that is usually only necessary every 2-3 years.

Attention: bark mulch is not suitable for orchids!

Water-retaining sphagnum moss (Spaghnum)

Which soil for orchids - Fresh or dried peat moss (Spaghnum)

The material from New Zealand is dried and pressed, while the European variety is sold fresh and alive. However, both have the property in themselves of being able to absorb and retain a lot of moisture. And this is what makes it so popular for the moisture-loving orchids. It serves as an additive for the orchid substrate, which is spread on the substrate surface, but must be replaced annually with fresh. It also allows oxygen exchange in the best way.

Mixing perlite into the orchid substrate

Some people swear by small amounts of perlite as an additive to the substrate, others like it less because it quickly sinks to the bottom when watered and floats to the top when submerged. Whether it is suitable for you, you simply have to test. However, the fine volcanic rock is perfectly capable of retaining water and also reduces the weight of the overall substrate due to its rather airy structure (it has plenty of pores).

Mixing soil for orchids with gravel or sand

Quartz gravel as drainage and coarse sand for loose orchid substrate.

Earth orchids, those in potting soil or other denser substrate, you can add coarse sand to increase or guarantee air circulation. This will also prevent waterlogging by increasing water permeability. It is important that you use only quartz salt, as this, unlike other types, does not give off salts. Lime is then also no problem.

Gravel, in turn, is suitable as an admixture to prevent waterlogging, i.e. as drainage. River gravel or quartz gravel is ideal. This type of drainage and substrate is also very convenient if your pots tend to fall over. The pebbles make the container more stable. Theoretically, the plant could also grow completely in gravel, but this would greatly increase the weight of the vessel, so pebbles are used only for the bottom.