New roots don't grow into potting medium, non of them.
 

I have a Vanda (Neofinetia) falcata shutennou that grows plenty of new roots, I counted 9, but all of them refuse to grow into the potting medium, but the spread horizontally. Crawling over the rim of the pot.

I decided to unpot as I wanted to repot anyway, and have a look at he roots in the potting medium and they looked good. Not perfect but no rot. And the bark wasn't decomposing yet but indeed not good enough for another full year.
I thought it had to do with potting medium gone bad.

The plant didn't wobble in its pot.
Now I write this I wonder if it started after I repotted the previous time. Maybe it doesn't like the bark I used? There was more root growth above the surface than in the pot. On the other hand, before repotting it did the same, but not this extreme. Is it a variety characteristic? Maybe?

I forgot to make pictures :(( .
Basically the old roots were growing in the pot, while the new roots were spreading horizontally while crawling over the rim. All of the new roots.
What could be the cause?

I gave the plant new bark. I planted the new roots just below bark level with grow tips downwards. That was easy as the new roots were very flexible. I know the roots that were spreading horizontally above the potting medium can't adjust, but hopefully, with the new potting medium, the roots decide to stay in the pot and grow downwards.

Any insight is welcome.

What size bark was it? How old?

Some years ago I received a nearly completely rootless Neofinetia from our now infamous Dutch orchid vendor which starts with a 'C' (you know who I mean). I had it in bark and top dressed with a good layer of sphag so that the new roots could find some moisture. It worked well, and after it recovered I was quite surprised when repotting it to see that most of the roots refused to grow down through the sphag and stayed superficial.

The Neos which do grow nice downwards roots are either in the traditional sphag mounds with hollow cores (so very airy) or in bark in net pots (a la Nardotto), so also very airy. Neos are vandas, so like a nice airy medium.

I use sphag mounds. I find the season's new roots kind of grow wherever they want over the mound. the old roots (in the mound) will branch. next time I re-mound the newest flush of roots, usually no longer growing, gets tucked into the new mound.

I let mine run wild... they end up growing with the roots down and around - like Vandas! (I have some with 3 foot/1 m roots, in hanging baskets) And happy. Clearly the controlled approach works, it has been a traditional Japanese practice for a very long time. But uncontrolled works fine too. Your choice...

Thank you all!

Reading your answers, I know where I make a huge mistake. Trying to contain their roots while, like Camille pointed out, they are Vanda's!

Camille, the bark was less than a year old, great size for my other plants but not for the "Neofinetia" when evaluating the past year with these plants.

All of you are absolutely right pointing out the "Neofinetia" roots need air, lots of air!
I checked, I have 2 small (might be a bit cramped) net pots and 2 clear pots left. I choose for the (net) pot in pot method. PiP.

I'm going to repot these plants today and will upload pictures for people that are not familiar with this potting method.
I currently have 2 Vanda's (tricolor & lamellata) potted like this and loving it.

Here are the pictures.

Firstly showing Vanda tricolor, bought from Nardotto e Capello. It was potted like this. I call it PiP, pot in pot.
As you can see a black net pot is placed in a larger translucent pot and kept from the bottom of the larger pot, with some packing peanuts.
https://i.imgur.com/pwXACKw.jpeg

This helps to contain some humidity for longer than when completely bare root, but at the same time allows plenty of air around the roots.

Let's look at the newly potted Vanda falcata Shutennou pink.

I didn't use packing peanuts to create extra space around/under the black net pot because the larger translucent pot is a cone pot and holds the net pot up anyway.

What I did though, is centering the net pot with some inert packing material, this also helps to stabilize the pot in the larger pot. Else it would wiggle and like we all now orchid roots don't like that.

https://i.imgur.com/K4UIuzJ.jpeg

I doubt if I should lift the net pot a bit but the base of the plant is at the same height of the rim of the largest pot. I assume this is ok.

Those new roots look fanstastic. They probably will head down into that air space Rather than filling in with anything, maybe must a wire over the top between the fans, to keep the pot in place. The roots will fill in the space fairly soon.

Thank you Roberta.

Yes those roots do look great and I have 9 of them, all from this growing season.

The other plant however isn't that vigorously growing. Curious to see if changing the growing conditions will make the difference for her.

Compare these roots with the roots from a months ago when I potted her up like this.

She loves it!

https://i.imgur.com/NOita39.jpeg

For me, roots outside the media are not a good option because my air is too dry. I just steer the roots into the media however i can. If they a several inces long i can usualy bend them and point them into the media, or sometimes I let the velamin snap so i can get them to go.