vermiculite - Orchid Board

Dima · #1 09-05-2011, 04:40 PM

How durable is pure vermiculite? I have phal stuartiana up for repotting: it's in coarse bark now, but the bark has begun to decay. I'd like to try to grow it in pure vermiculite. Never used pure vermiculite before, though, so if it's a bad idea pls let me know. Thanks in advance!

Bud · #2 09-05-2011, 04:57 PM

Its not a bad idea but you need to mix it with other media...by itself it is tiny particles; unless you can get the large ones average 4to 6 mm at least...the commercial ones being sold are fine and sandy and I dont think your phal will like that...I have a phal on LECA on S/H method where the clay pellets are 4 to 8 mm in diameter.

Ms T · #3 09-05-2011, 05:10 PM

I would advise against vermiculite. Like Bud said, most kinds you can get are very much like sand, and when wet, it compacts very much. I recently had changed my houseplants' potting soil to a mix with vermiculite - all but the nephthytis and dragon trees hated it. It would be far too smothering for a phal, and I'm not sure how it would work in a mix with bark, perlite, or charcoal. It may just end up sticking to that when watered.

camille1585 · #4 09-05-2011, 05:10 PM

Vermiculite is usually used in mixes (for both orchids and normal plants) to increase water retention and aeration. So I assume that a vermiculite-only mix would take a very long time to dry out, which is definitely not a good thing for orchids. IMO, if you want an inert potting medium, you are much better off using hydroton/leca.

Merlyn · #5 09-05-2011, 05:15 PM

Yes, not only does vermiculite/sponge rock retain water it compacts !

There are many brands of leca (light expanded clay aggregate). Hydroton, Prime Agra, and AliFlor come to mind.

silken · #6 09-05-2011, 05:16 PM

Quote:

Originally Posted by camille1585

Vermiculite is usually used in mixes (for both orchids and normal plants) to increase water retention and aeration. So I assume that a vermiculite-only mix would take a very long time to dry out, which is definitely not a good thing for orchids. IMO, if you want an inert potting medium, you are much better off using hydroton/leca.

I agree with camille and the others that it would be too fine, sandy and moisture retentive. New course bark would last a year or two and it's what the plant is used to.

Orchid126 · #7 09-05-2011, 05:30 PM

They are also no longer recommending vermiculite as inhaling the tiny particles can cause lung cancer.

keithrs · #8 09-05-2011, 05:31 PM

I have got seedling that used it in a mix and the roots where rotted.

I recommend a mix of LECA, CHC, and charcoal and use a airy pot. You my have to water more but helps alot in keeping the roots heathy.

Dima · #9 09-05-2011, 05:32 PM

Thank you all for the fast reply! My other phals have all been repotted at least once, they are all either in sphag or in fine bark (this is a low-humidity environment, indoors under a ceiling fan; coarse bark holds too little water when it's new, too much when it's old; not good either way). This phal is the last one I haven't moved out of its original medium yet, so I wanted to try an inert medium to see if it works better. Guess it's time to shop for LECA

. Thanks again! Dima.