Did I miss something - dirt...
 

So I purchased an orchid (the Miltonia) in December, and also was given the Burrageara by my orchid society (they are awesome).

But this is pretty strange. They are beautifully grown plants - you can tell they were given great care. But they came in some sort of dirt-like media. It looks like pretty loose -cake like - peat moss with maybe a little perlite in there.

Do I leave these things be? Or repot after flowering? Repot immediately? I really haven't watered these things but once or twice when the dirt looks nearly dry. Its an odd thing - did I miss some potting mix revolution?

I would ask the OS who donated it and ask them what it's in. Could be Aussie Gold. If the plant looks to be thriving, I would leave it until early spring when new roots should start pushing out, and repot it in something you are more comfortable with.
Use a wood skewer pushed 3/4 depth into the pot to see how moist the mix is before watering.

Bill

Miltonias and Odontoglossums are related to Oncidiums, but have adapted themselves to live in cool, moist environments. Seattle is probably a very good spot for these sorts of plants. I have never seen the kind of potting medium the plants are rooted in. It almost looks like leaf mold as there seems to be little if any of the porosity one finds in fine fir bark. The outer clay pot seems to suggest this plant was watered at least once a day and the water was allowed to drain out of the pot. A general rule to follow with any new plant is to do nothing except watering until the plant begins active growth again. Many Orchids are repotted at this stage, but the plant is usually growing over the side of the pot. It looks like your plants still have plenty of room to grow. I suggest you do nothing but keep the new plants cool and evenly moist for at least the next six months. If they are still alive by then you will have probably learned what they need to grow best. It may actually be 5 years before you really need to repot them.

I see a new growth in the last pic. If so, this is the perfect time to repot, before that new growth throws out new roots.

I've seen similar medium used on oncidiums. It makes me uncomfortable and I'll switch mediums. Six months is a long time to be uncomfortable.

If this was a commercially grow plant, it was watered when nearly dry, with lots of air movement, and kept warm (80*f). That is why it can grow in this commercial inexpensive media. Once we get it home, our environment is cooler than what it was grown in with little air movement and so death lingers in the shadows. If this were my plant I would water it very little until the new growth started to push roots and then I would pot it up in a medium bark/chopped sphagnum/sponge rock media. That way you can water it to your hearts content as long as you give it lots of air movement. Air movement, so important to good orchid culture, is seldom mentioned here. It is vital. I will wager that this plant will succumb in 6 months or less if it is not repotted as soon as the new growth gets roots, this isn't given good air movement, and it is not given adequate light and warmth.

Thanks for the info on how they are grown commercially - this actually makes a lot of sense - cost of potting media / growing temperatures of the commercial nursery, and probably cost of watering in a fir bark in addition.

I unpotted both yesterday and indeed - it was Aussie gold or some such potting mix. I got the Milt from the grocery store - but yeah, it does look like it wasn't given very good air movement with high humidity.

I potted them in mixed NZ Sphag and Med Fir bark (what I had lying around) - and they look really nice in their new home.

There isn't much for new growth on the Milt. (there is a baby nubbin, but my guess is it won't send out any new roots for 6 months). I was going to wait for it to finish flowering, but it has already been going 2 weeks, I figure if it wants to save energy it will drop those flowers.

The Burrageara will be fine - it has two new pseudobulbs growing and should be pushing out new roots very soon here.

Those peat & perlite type mixes are also quick and easy to repot with. Commercial growers for mass market sales often buy bare root near blooming size plants in large quantities, pot them up quick in the peat mix, and grow them for just a few months until they bloom. They don't care about long term health of the plant, just the quickest cheapest way to get them to blooming size in the near optimal greenhouse conditions. If the roots rot as soon as someone gets it home they don't care.

Very good info Madman. You are absolutely correct. Commercially mass produced get nice flowering plants but at the expense of death later on down the road unless we make changes.

I bought an onc potted in similar medium. (grocery store also) unfortunately the flower stalk got bent in transit so I lost the flowers much sooner then I should have on the up side it allowed me to re-pot it sooner. It seems happy in the perlite/spag coconut coir mix I use it's little off shoot bulb is getting bigger and greener since repotting. My vote would that the re-pot will do it good.

OK, I got some orchids from trader joe's -- some intergenerics and a miltoniopsis -- and they were in that media. Too worried about the media and seeing some white material buildup, I repotted them. When unpotting, the roots were really healthy and growing. So I would wait until there is some active growth before repotting, don't rush.