Treating Raw Bark
 

Up to now I've been using Orchiata bark and I am quite happy with it. Only issue was its wettability and started experimenting with ways to improve this. My only experiment was to moisten the bark with an urea solution (to compost the surface of the bark). Seemed to improve wettability.

Now my regular supplier of Orchiata can't be contacted and so was forced to locate other sources of bark. I came across Kiwi Bark (pinus radiata bark). The supplier said that it is untreated in any way but can use it right out of the bag. When I mentioned nitrogen drawdown and wettability he said I can treat the surface for a week or two and that will also get rid of any oils on the surface of the bark as well as improve wettability.

My question is does raw (untreated) pine bark need any treatment before use and if so how should it be pretreated?

BTW this untreated bark is supposedly being used by a few major orchid nursery over here in Australia as well as in the US - Fred Clark of Sunset Valley Orchids uses Kiwi Orchid Bark exclusively (ref. Sunset Valley Orchids - Superior Hybrids for Orchid Enthusiasts)

Fred Clarke's plants grow beautifully in it. I don't repot plants I get from him right away, unless they're outgrowing the pot, because the bark and seedlings are always in excellent shape.

Since starting this thread I've done some further research and have asked, directly or indirectly, commercial growers who use Kiwi Bark about any pretreatment they do before using the bark.

I started with Fred Clark (Sunset Valley Orchids) about whether he pretreats the bark. His answer (verbatim) is as follows:

"I've been using kiwi Bark for eight years straight from the bag no soaking or any preparation before hand. I've used it on many different types of orchids over 1 million have been grown in it over the years. It will last 3-4 years with no appreciable decay. The Ph also is pretty stable over that time."

Some however do soak the bark (Jeffrey in Hawaii, I am told, does soak). As to what type of soaking is performed various people do various things. However the local supplier tells me that most do not and use it straight out of the bag.

Local (Australian) orchid nurseries who are using it include: Bill Miles (Orchid Species Plus), Hans Schieble (Dark Star Orchids), Grahame Young (DUNO /Elermore Orchids) and Phil Spence (Orchid Productions). I'd say that's at least 40% of local orchid production.

A key feature of this product seems to be its stability over time - structural and chemical. It seems it does not break down easily and its pH is also very stable. This stability is a very important for commercial nurseries as it reduces the need for repotting and repotting is an expensive (labour intensive) exercise. I am also told that more watering than for other bark types is usually applied when using Kiwi Bark.

BTW I have no financial association with the producers\distributors of Kiwi Bark.