Understanding the Relationship Between Orchid Media & Water

In Orchids
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You know how there are some people who say, “_______ is the best way to grow orchids”, when referring to bark or sphagnum or semi hydro? And then a bunch of other people will say, “everything works differently in your individual climate”?

That’s obviously true…but maybe there’s a nugget of science that can help us all understand why one method or potting media works for a person (while that same method could be catastrophically bad for another person’s orchid collection)…

I did a pretty simple experiment to test the water-holding capacity of different orchid media and the subsequent dry-out rate (in my climate). The results were pretty interesting.

The question: Which orchid media holds the least/most water and what effect does that have on the dry-out rate?
In other words: which potting media will dry faster or slower (or too fast in a dry climate vs. too slow in a humid climate)?

Results: 1/2 cup of Media vs. Water Weight Held (When Media is Saturated)

  • LECA: 27.4g of water
  • Pine Bark: 37.02g of water
  • Blended (Fir bark, pumice, sphag): 50.77g of water
  • Sphagnum: 102.4g of water

These results make it clear to me why some people love sphagnum, while others love LECA, right? Because for those people, their climate, and the type of orchid they’re growing “it just works.” But if your climate has a low humidity, then LECA will be bone dry in a day or two (or at least the top-layer will be if you’re using semi-hydro) and conversely, if your humidity is high, then saturated and compact sphagnum moss might still be quite wet after a full week.

This is why I use a blended mix – I can customize the dry-out rate based on the needs of the orchid AND MY CLIMATE.

It’s a simple experiment and probably a bit of a no-brainer, but I hope this helps give others (new growers especially) some perspective on different media and their relationship to a person’s climate. It’s also illuminates why some things work for one grower, while they might not work for you…maybe it all just comes down to water?

If you want to see the rest of the results, check out this google sheet.