Water Holding Capacity of Approx. 40 Medias

[mayres]

Note the water holding capacities of nearly 40 medias used for orchids. This chart is copied from rePotme.com and was established using the products that they sell, but this chart will also give you an idea of how similar medias made up by others or yourself will compare.

The four numbers after each media is the

1) Orchid Media Dry Weight per quart (in ounces)
2) Wet Weight per quart (in ounces)
3) Water Held per quart (in ounces)
4) Water Held (as % of weight)

Aerolite 1.2 2.8 1.6 133%
Aliflor - Small 17.6 20 2.4 14%
Aliflor - Medium 12.8 14.8 2 16%
Broken Brick 38.4 40 1.6 4%
Charcoal - Small/Medium 4.2 11.4 7.2 171%
Charcoal - Large 3.2 8.4 5.2 163%
Cobblestone 49 50 1 2%
Coconut Husk Chips - Small 4 10.4 6.4 160%
Coconut Husk Chips - Medium 3.6 9.2 5.6 156%
Coconut Husk Chips - Large 3.2 8 4.8 150%
Coconut Husk Fiber 1.2 3.2 2 167%
Coir 6.4 18.8 12.4 194%
Diatomite - Small 16 25.6 9.6 60%
Diatomite - Medium 11.6 21.6 10 86%
Diatomite - Large 10.8 19.6 8.8 81%
Fir bark - Small 8.4 10.8 2.4 29%
Fir bark - Medium 7.6 9.6 2 26%
Fir bark - Large 6.8 8.4 1.6 24%
Granite Chips - 43 44 1 2%
Marble Chips 47 48 1 2%
Metro Mix 380 (with Coir) 10.8 20.8 10 93%
Packing Peanuts 0.4 0.4 0 0%
Pea Gravel 42 45 3 7%
Peat Moss 4 18.8 14.8 370%
Pro Mix HP 4.4 20.4 16 364%
Pro Moss - Fibrous Blond 4 18.8 14.8 370%
Pumice Rock 18 28 10 55%
Redwood Bark 5.6 7.6 2 36%
Rice Hulls 4 8 4 100%
Rockwool Cubes 1.2 15.6 14.4 1200%
Sphagnum Moss - Premium Long Fiber 3.2 9.2 6 188%
Sphagnum Moss - Premium Chopped 5.6 9.6 4 71%
Sponge Rock - Small (Perlite) 3.6 10.4 6.8 189%
Sponge Rock - Medium 3.2 10 6.8 213%
Sponge Rock - Large 3 9.2 6.2 207%
Tree Fern Fiber 2.8 4.4 1.6 57%
Vermiculite 4.4 22.8 18.4 418%
Volcanic Rock - Medium 18.4 23.6 5.2 28%
Volcanic Rock - Large 25.2 28.4 3.2 13%

[evagentry]

thanks Mayers, this is interesting information now to be able to apply it!

[kmarch]

This is magnificent!!!! What a resource! And practical! We can use this list when deciding what potting materials will give a particular orchid the moisture level it prefers.

Only one question: Are the ounces in #3 "Water Held in ounces" a measuring the weight of the retained water or the volume? e.g. are they weight ounces or fluid ounces?

[Tobi]

Great information Mike. Thanks. The rockwool cubes have an amazing water
holding capacity. I had started a post a while back inquiring if anybody had
used this before as a medium. Wonder if it would be good for Phrags.,
especially if you were away for while.

[pikevi]

Thanks for the list, mayres. Such compilations are hard to come by.

[Vivienne]

Thanks Mike! Great information... which has now been printed and added to my 'Orchid Book'.

[WIB]

The headings at the site indicate clearly that it's water weight not volume in ounces. I assume from the other headings that they weighed the medium, saturated it with water, allowed it to drain fully, and then weighed it a second time. -- Bill

[mayres]

Kevin - I'm quite sure that they are speaking of weight ounces.

[m3phist023]

Wow, I always assumed that coconut husk chips were dryer- but they seem to have a pretty good capacity for holding moisture......
I though sphag would definitely be higher.

I've seen rockwool in my local nursery's "orchid section". I never knew what it was for. Is it generally mixed with other types of media, or used on its own?