Using Diatomite as potting medium

[King_of_orchid_growing:)]

Here's my .

Freshwater diatomite is fine to use, but it depends on the growing conditions each person has and what kinds of orchids you will be growing them in.

Yes, it is possible to over water using diatomite.

It also has limited pest control capabilities. It will not deter all pests.

Overall, it can be useful, but it can also be not quite so easy to use.

[chromebright]

With all due respect to the LECA and Hydroton crowd, my experience with both LECA and Hygromite and Dyna-Rok II (both are brands of diatomite) as media for S/H has resulted in almost exclusive use of diatomite for S/H. Identical growing conditions with keikis from Dendrobium kingianum using LECA and Hygromite have resulted, after one year of growing, in plants that are double the size in hygromite. A few Paphs and Phrags seem to like LECA (Paph Green Lantern for example), but by and large nearly all my orchids that like S/H like diatomite better than LECA. I have no good explanation for the difference, as both media are supposed to be inert and neutral. Both were treated the same by washing thoroughly and prewetting in KLN solution. Both were watered the same and flushed monthly with pure R/O water. My observations of root growth showed, in many cases, that roots in LECA were growing out of the media and that those roots whose tips were touching the LECA had dead, black tips instead of healthy green tips. In no cases were there black root tips when diatomite was used. My precious Paph sanderianum seedling had 100% root loss in LECA, even though I used an underpot warming pad. Its twin is being grown in a mixture of perlite, lava rock and charcoal (non S/H) and has not experienced any root loss.

[Ray]

Ken,

Higromite looks and performs a lot like diatomite - except for the color - but as it contains a lot of volcanic ash, so is chemically different.

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Ray:

I wish I could find a source for the Higromite again. Just started using the Dyna-Rok II instead and wasn't aware of the volcanic ash difference between the two. Yes, the color is a bit different. I don't have as much experience with the Dyna-Rok II as I do with Higromite, so I can't really comment on the differences yet.

Thanks for the information.

[Bayard]

I've used diatomite about 50% with coconut husk chips.

The plants that are in this mix are in clay pots.

They have to be watered carefully because the mix holds water for a long time!

[chromebright]

I'm finding Higromite is available again from a variety of hydroponic retail sources. The cheapest I've found it is from igrohydro.com (that's because shipping is within California), but in general shipping is going to cost more than the product itself.