When & how often to repot?

[tinarae]

I think it's been 3 or 4 years since I've changed the medium in my mini slc. How often should it be changed? I hesitate to do it when there's new growth, but that's pretty much all the time. I have mostly minis that never really outgrow their pots, but I do worry about the quality their bark. How about orchids mounted on sticks? Does the moss ever need to be changed on those? How would you even change that?

[Shirley]

I don't grow on mounts so can't help you there. I try to repot the ones in bark mix at least every two years. The ones in moss I try to change every year as the moss tends to compact. Of course there are a few kinds that just hate to be repotted and will sulk for some time after such as Dendrochilums, Paph. rothchildianum, Den. aggregatum. Those I'll leave three years or more.

[tinarae]

Whew! I was worried that maybe I was supposed to be doing it every year! I do have one in moss, but I suspect that I enjoy watering too much so I try to keep most of them in bark.

[AaronM]

When the medium looks more like potting mix than orchid mix, it is time to repot. Soak (1-48hrs) or boil (15min and them let it sit until cool) new medium in water with diluted, high phosphorus fertilizer and/or KLN or Superthrive (add these only once cool if boiling) before you use it so that it will retain moisture and stimulate root growth. It is never a good idea to boil new medium after the orchid has been added.
Only change mount moss if there is a disease or bug problem. Remove it from Dendrobiums and other "dry" orchids once their roots are firmly bonded with the "wood". This type of setup looks very natural and allows you to know exactly what's going on with the roots.
Last thing: NEVER, EVER, EVER, EVER USE SPHAGNUM MOSS AS THE PRIMARY MEDIUM FOR ANY ORCHID (this is true of 97.8% of orchids). In most cases, the moss either rots out the roots or withers them. Growers use it on plants going to market because it's cheap and will keep the plant alive long enough for you to buy it (if it dies after that it's good for their business).

Aaron "Master of Medium" M

[Cookiemonster]

To tinarae its time to change the medium when it depends on what the medium is and how long its been sitting there. Moss should be repotted once a year, bark mixes about every twoish years and a bit longer for coconut husk, please take all of this with a grain of salt. You will know when the plant needs to be repotted, the medium will be visibly broken down and possibly the plant will have overgrown it.

Hi Aaron, while i see your point in sphagnum moss being a medium that has not worked for you, I think its fair to say that everyone has different conditions and grows their plants differently. I personally have most of my plants in sphagnum moss and wouldnt have it any other way, and fyi they are thriving!

If you take a look at many of the Japanese growers who have immaculate plants, do so in moss! Its all based on your conditions I guess thats the key

[buckie]

There is a very good lesson here, what works for you in you area of the country (World) does not mean it works everywhere, here in tropical Nth, Queensland, Australia, most of us use rock, either volcanic or granite, about 1/2 inch pieces, we grow outdoors all year round under 50 - 70% shadecloth, repotting is done between 2-3 years depending on the plant.

Warren

[AaronM]

Cookie, living in AZ, I would imagine that moss might work for you since it probably dries within 3-7 minutes after you water it. However, any place without Saharan humidity levels (like you have there) you will find that the core of the moss takes way too long to dry out and causes the plants to die. I work for a retailer that sells "factory" orchids and I can tell you that I watch hundreds of orchids a year go into the dumpster and the ones in straight sphag usually die the fastest.
However I do concede that I may have overstated my point about sphag, so I will edit out one "ever" and change "99.9% to 97.8%.
As for the Japanese, they eat rice with sticks and have a half hour long ritual tea service so I think it goes without saying that they are, more often than not, the exception to any rule. If that nut job suing Miley Cyrus is reading this don't bother getting offended, I'm part Japanese.

Aaron "Loves the Japanese but Still Hates Sphagnum" M

[camille1585]

A large part of my orchids are in barkm and I repot every two years, and sometimes every year for the phals. My phals seem to enjoy the change, thy go into a growing frenzy shortly after. For the ones in moss (japanese orchids mainly) I've had them a year almost, and the moss is starting to look a bit wierd. I'll probably repot them in the spring. As for the mounted ones, I'm not touching those until the sphag gets really icky. Even when I remove it, I don't think I will replace it, since I have bare footed mounts doing really well.

Aaron, I've seen the 'factory' orchids in sphag too. For me, the reason those die so quickly is largely due to the fact that the sphag is packed very very tightly, so the core can't dry properly. If an orchid is planted properly in sphag, i.e., the sphag is loose in airy for the pot, it works well. I know people who have great success with sphag, others that don't. My Neofinetia are in japanese moss mounds, and since the sphag is loose with an air pocket in the center, it works like a charm, despite somewhat high humidity. (and I'm not japanese )
So while, sphag may not work for you, keep in mind that depending on how tightly the orchid is potted, the conditions and how a person waters, it is as good a medium as anything else.

[Bolero]

Certainly not every year although sphagnum won't do well if not changed every year. I think Cattleya's should be repotted every 3 years unless they outgrow their pots earlier than that. But that's just me......???

[rogerman]

All of the Cattleyas that I have are grown in one single block of coconut husk. If i tried removing the husk to replace it, i'd kill every plant that I have. If the plant grows out of the pot, you almost always see a place on the plant to split it, so I cut the keiki off and pot that..... If the plant needs a bigger pot, I just soak the plant for about ten minutes and pull out of the plastic pot and repot the plant and original coconut in a bigger clay pot and pack with coconut.