Oncidiums and Potting

[atcrosby]

I continue to have issues with my Oncidiums Alliance plant where they don't seem to be thriving. This weekend I spent some time investigating the causes. It appears in my issue is the medium where the top is dried out and the bottom portions is wet. This comes after a full week with out any additional water added so I am wondering if this is preventing the roots from growing and filling the pot.

My medium is a bark / charcoal mix. This past week I purchased from QuarterAcre Orchids, JF's Excellent Oncidium Mix which is Small wood chips, diatomite and a 'special ingredient' which is calcium. I repotted some of these oncidiums (One Wilsonara and the ever mysterious Intergeneric Oncidium) in this stuff. Thinking the bottom is never becomes dry, I put styrofoam peanuts on the bottom of the pot so 1/3 of it is inert material and the medium on top of this.

I should mention these pots sit on top of humidity trays since these plants are all grown in my bedroom where they get S/W light. Could the humidity trays be playing a role in keeping the bottom of the pots overly damp? Also, the pots are azalea type pots with holes only on the bottom.

Any suggestions from the experts?

[Aniko]

I encountered the same problem with my oncidium (Wet bark at the bottom), dead roots.I did the same tricks with Styrofoam + I perforated the whole plastic pot, using a heated wire. The disturbance set back the plant for few weeks, but now some fine roots started, they looks like rice. Hopefully, yours will do the same just need some time to start.
(I don't use humidity tray, even though I have air conditioning).
Aniko.

[arleneg]

Tom, make sure you have a gap between the bottom of the pot and the humidity tray so air can pass through the pot bottom. When I water my oncidiums, I let water trickle down the potting medium (bark & perlite).

[Cynthia, Prescott, AZ]

If you really want to turn your plastic pot into a basket for drying out your plant, use a hot glue gun to melt holes into the pot. I look for the largest nose on a cheap chinese glue gun. How about only putting the holes in the lowert half and accross the bottom?

For those that have a problem with the pot not drying at the bottom, there is the possibility that you are not packing the mix into the pot well enough. The mix should be well pressed into the pot, with the roots wet before hand to allow them to bend to the pressure on them without breaking. This heavy packing will result in much better wicking of moisture thru the pot. If you place the mix gently or lightly into the pot, you can expect this problem even with air under the pot, assuming the usual holes in the bottom. Azalea pots are great. Bulb pans are even better for the larger plants. Cynthia

[Aniko]

Cynthia, thank you - I think you pinpointed the cause of problem !!!
Indeed, the bark isn't packed at all...
Aniko.