help with oncidium roots gone wild

[Junebug]

I would split and repot unless you can figure out some way to provide the upper roots with more moisture.

Last year my large Onc. Sweet Sugar developed upwards growth like your plant and it did become a problem. At first she was a vision of health, however the new roots from the new upper bulbs were not receiving enough moisture to support their growth and they were drying up before they could reach the pot. I kept them misted and even tried adding more SH pellets between the bulbs but nothing worked. My oncidium convinced me that she was past due for a repot when her new leaves began yellowing at their tips.

I noticed from your pictures that your plant looks healthy and that it's potted in a bark mixture (mine was SH), so maybe this won't be a problem for you. Instead of repotting you might try tucking some lightly packed sphanum around the bases of your new growth.

This experience was a lesson for me. Splitting and repotting the multilevel growths was not an easy task. In the future I will not allow my oncidiums to get too large before splitting or repotting. Mine had filled it's 7" pot to the brim and I think it was just looking for some place to grow and upwards was the only option.