The tolumnias look healthy. Oncidium too. I like them in an empty terra cotta pot high in the pot. Add a big rock or something. But leave a lot of air near the roots. That is why higher in the pot. With clay pots in your climate water daily. It might need a root stimulant. Check with your supplier or internet. I use maxi-crop. great stuff. Sold in India? I would not know. You can contact the company and see if there is a way... http://www.maxicrop.com A good root stimulant is a game changer! If it works for orchids it will work for any plant with roots. Worth having...

The Tolumnia are twig Epiphyes. Should be fine in your climate, but note that the usual instruction is must dry by nightfall. Those channeled leaves are there to collect dew in drier times where the ancestors grow in nature.

Best underpotted in well draining tiny pots in a quick draining mixture.

Good luck and read up on all the complete culture notes you can find on the net.

Thanks.... And may I ask what the root simulant will do exactly?

Also can I use coconut coir as the media for tolumnias , I am planning on just inserting lives of coir between the holes in the pot...Will this do good or bad?? As I live in South India....We have high temps. I hope that the coir will help in water retention.;)

You do not want water retention! If they get watered, they need to dry a bit before they are watered again.

No idea how to grow them in the tropics, but the usual cause of death is over potting and over watering.

Maxi crop or a root stimulant will provide strong, healthy, and fast growing roots. Roots to a plant is like a heart to a mammal. In turn the plant grows big and healthy. With orchids you get immediate feedback because many of the roots are exposed. Look for translucent root tips. That is the tell about root health. And the plant responds...

I also have a wierd idea... There is this gross concoction from cow products called panchagavya (look it up in the net).. which is used in India as a fertiliser ... Can use it in very dilute amounts??

Thats my problem... The roots of the tolumnia are not translucent...Or plump....Thats why I thought of the coconut coir idea...And they dry up pretty fast in here

The roots are very dry and papery and some are even hollow... The leaves are shriveled and the edges are dried up...

So now should I use coir or not?

and P.S. the Oncidium is in a pot with no side holes but has holes in the bottom