wetness when repotting Oncidium?

[HotPot]

I have potted into Hydroton from bark as I want to try the semi hydrponic method. I trimmed away all roots that were not newish and white. Now Watering - do I fill the bottom of the pot up to the drain hole that is 2.5 cm from bottom or do I leave it a bit dry until roots start to grow? I have of course soaked and washed the hydroton first.

[tom499]

I have found its best to keep plants on the dry side when moving into S/H. Like with all repots, it is best not to water for a period after repotting, to limit rot that can occur on roots damaged by repotting etc.

Oncidiums have the luxury of psuedobulbs, so will be happy to have their pot dry out between waterings.

Once new roots start to grow you can look to water more often.

[Ray]

I'll both agree, and disagree with Tom on this one.

1) It is perfectly fine to let the plant dry out for a few days after removing it from the old medium. As he said, it helps prevent rot from occurring by letting the wounds dry out. However...

2) Once the plant starts putting out new roots, in order to get it acclimated fastest to the new root environment, you MUST keep the medium saturated, so those new roots will tailor themselves to that environment.

I'll also add that you should never just "top up" the reservoir, but always fill the pot rapidly to the top, saturating and flushing the medium, and refreshing the reservoir will all new solution.

Also, expect all of the existing roots - those you left on the plant at repotting - to die after a few weeks. (Hence the need to make such a change right as new roots grow.)

[HotPot]

ok thanks for the advice, I will try keeping it dryish for a few days. I did cut off most of the roots and there are some nice young white roots left.
The most important thing I got from this was a side point about not just topping up - a mistake I was bound to make - thanks for pointing that out.