What’s the best potting mix for your miniature orchids?

Oncidium sp mounted on tree fern

There’s a lot of choice when it comes to orchid potting medium, Here’s your first tip. There’s no right or wrong there’s just experience and this makes the choice easy and personal.

You need to know a few things first so lets look at a selection:

Bark: Bark comes in different grades. The finer ones are best for seedlings. The finer bark will break down faster.Cheap; easily obtainable; good aeration; and good drainage.Organic material breaks down and becomes too wet; not easily hydrated when fresh; dries out too quickly; needs replacing regularly.
Quincan or scoria is a volcanic rock. It’s hard and grey.Porous and doesn’t degrade. Its relatively cheap.Can be heavy. It’s hard to determine if it’s dry.
Sphagnum Moss is a moss found in peatlands and bogs.It retains water really well. It allows easy penetration of roots, especially for baby orchids. It is very light. It is mould free.It’s expensive and can be hard to find. It can be too wet for some plants.
Coconut chips or fibre from the coconut palm.It’s organic and mould free. It’s lightweight and relatively cheap. Long lasting. Its porous but retains water well.It will break down and need replacing.

Most tropical orchids are epiphytes. Their roots need air. Some roots, the ones with green tips, photosynthesise. To do this they need light, which is why they love to be mounted or grown in pots or baskets with lots of holes.

Orchids’ thick fleshy roots can utilise a tiny drop of moisture. So any mix that you use in a pot must take this into consideration, ie it must not stay too wet. This is why clay pots are preferred. They can indicate moisture levels in your mix. If they are damp and cool, then the mix is moist. If the mix is dry the pot will feel light and warm.

So how are you able to use any of these mixes? First, be diligent with your watering habits. If the mix is wet, let it dry. Know that orchids are drought tolerant, so rather than soaking the whole pot, misting is also a good practice.

This list is not complete, but it’s relevant to my experience. I use bark and sphagnum moss and terracotta pots and mounts. I make my own clay pots but you can get really cheap terracotta pots at bigger garden centres.

Know your orchid’s water requirements. Don’t over-pot, and don’t over-water in winter. For more on growing orchids. See my series here

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