Slippers and re-potting

[Hummer344]

In the current issue of AOS, an article on the above states that they should be repotted each year. I have seen threads advocating this on the forum here, but!!!!!, what is the reason? Most of my orchids stay in their medium until they get root bound & don't seem to suffer. Whats the difference?
Thanks

[mayres]

I think it has everything to do with the quality/type of the media that is being used. The issue is that you don't want your media breaking down and staying soggy. For example media with sphag or quickly (relatively) breaking down barks. I purchased a couple of paphs from a fabulous grower/hybridizer of them in my area last year and asked him if I should repot anytime soon and he said, "What for, would YOU like to be yanked out of your pot?" He uses a lot of lava rock in his media and he said not to repot until the plant basically is busting out - not expected to hapen for 3-4 years. On the other hand, I have definately root rotted several paphs myself - not sure if I just watered too frequently or my media was poor and broke down too quickly? As with many facets of growing orchids there appears to be many ways to "skin a cat" so to speak. We all seek to find what works for us and then stick with it until something better or easier comes along.

[Bolero]

They recommend repotting every year and in some cases they recommend repotting every six months. It depends on the grower, some people repot every two years. The quality of the mix is irrelevant but I would think the worse the potting mix the more often you would want to repot.

I find that Paphs have to be potted tighter than other plants. There are a number of reasons I can see for repotting annually:

1. It seems to kickstart active growth at the start of the growing season. They seem to move along once they are repotted in a fresh mix.
2. You need to check the roots, more than any other plant the roots on a Paph can determine the health of the plant. Although healthy roots are important on all plants often a paph will have one healthy active root and you want to make sure it is growing properly.
3. You want free draining open roots. In nature many paphs have roots that wind through the leaf litter and very close to the surface and therefore are exposed to a high level of oxygen. Often the roots grow in the top 2 or 3 cm of the surface. In pots they don't grow naturally and therefore may not get the oxygen they need to be exposed to, the potting mix needs to be open and free draining to ensure they get this. By repotting regularly and more often they should get the air they need.

Sorry I've typed this out very early in the morning half asleep. Having trouble sleeping tonight.......I hope this makes some sense. Paphs and Masdevallias both seem to benefit from regular potting where other plants seem to flower better when pot bound. The growth habits of all plants seem to be different and it's only with many years of experience that the experts recommend the different frequencies of repotting.

[maiseymoo]

Interesting thread, I have only had my paphs a couple of months but have repotted, now you are worring me, though I have to say that they look better. I suppose it is what works best for everyone and what they are grown in.

[kmarch]

Originally Posted by Hummer344

... [Pahps] should be repotted each year. ...what is the reason?

Other members have given specific answers to this question so I'll not re-state their good answers but let me give instead a "big picture" answer: Paphs and phrags like a "clean," fresh, environment for their roots to grow. They don't like stale, medium that is breaking down. I hope to show in this post how nature "repots" her paphs keeping them in fresh mix.

If we take a look at how paphs grow in the wild we'll see that they grow in leaf litter on the forrest floor and on rocky cliffs or even trees.
Here's a paph growing on a rocky outcropping
And on a cliff (the paph is located at the very top of the pic in the center)
And on the forest floor
And here's one growing on a tree trunk

Taking a closer look at those growing on the cliff and rocks and the one growing on the tree trunk (the first 2 pics and the 4th one) we can see that it looks like leaf litter and other deterius (sp?) has collected around the base of the plant. Perhaps there is a crack or pocket there that helps to anchor the plant and catch debris. If there is, it's probably not very big. The roots of the paph are probably not contained as they are the way we grow them and there's probably not more than a few cm (1/2 - 1 inch) of "natural potting mix" ( ) covering them. What happens is that a few leaves, maybe a bit of bark, maybe some twigs or a bit of falling moss are caught around the plant and begin (or continue) to decay. Eventually the pieces will break down small enough that the next rain will dislodge and wash away some of the more decomposed pieces. By the time this happens, fresher material (leaves, bark, moss, twigs, etc) is falling and being captured. In a way, it is like Mother Nature is perpetually repotting all of her paphs. As the old mix is rotting and getting washed away, fresh mix is replacing it. This keeps the paphs in a constant supply of fresh mix. They never sit in stale, mucky mix.

Looking at the paph that's growing on the forest floor the first thing I notice is that the forest litter that the paph is growing in really looks a lot like the mixes I see people grow paphs in. To my eye it looks a lot like a fine bark mix with leaves and tree fern fiber in it I also notice it looks like there are big pieces on top and smaller more decomposed pieces down below. It is not uncommon for mottle leaf paph species to "grow up" as it were, similar to a coelogyne, to have successive growths grow a bit higher than the previous growth. I have a Paph tonsum doing this right now. The base of the new growth is entirely above the top surface of the medium. This growth habit effectively keeps the roots of the new growths in the upper layer, where the more fresh forest litter is, rather than down where the more thoroughly decomposed stuff (the dirt) is found.

Originally Posted by Hummer344

Most of my orchids stay in their medium until they get root bound & don't seem to suffer.

You say "most of my orchids" but are they paphs? Paph roots are quite different than other orchid roots like cattleyas, etc. so are you saying that you leave your paphs in their medium until they get root bound?

Originally Posted by maiseymoo

I have only had my paphs a couple of months but have repotted, ... I have to say that they look better.

I wouldn't worry maisey. From my experience paphs don't seem to suffer much from repotting. I do avoid repotting when in spike or flower and from my observation the best time to repot does seem to be, as Bolero said, Spring. My paphs go through a summer-long growth spurt when properly repotted in the spring.