New - Need watering advice for Sharry Baby
 

Background: I have never kept a plant alive in my life except aquarium plants (my aquarium plants are flourishing). I believe I am a chronic overwaterer. BUT, the conservatory near me was selling retired orchids and I have fallen in love with the chocolate orchids they have. I have done a lot of a internet research, but there are so many options that I just feel overwhelmed. I would like a plan of attack that includes: bare minimum number of days I need to wait before watering again, estimate on how much water to give them, should I let them soak ever?, and do I want the bark to get completely dry or just mostly dry?

More specifics:
-potted in 4.5 in clay terracotta pots
-course bark potting mix
-using 6 in trays with pebbles and water for humidity (also, how often should I refill theses?)
-one plant has slightly wrinkled pbulbs but I think everything else looks good (question: does this one need a different watering agenda? if so, for how long?)
-plants are currently in a south facing bay window ie they have direct sunlight. I could move them to a north facing window where they would be like 5 ft away from the window instead.
-stalks have been cut off as they were brown (I sterilized the knife and used a dab of cinnamon on the cuts afterward). So they are not in a growing phase right now.

Thanks in advance for the help!

The first thing to grasp about orchid growing is that the plants do much of their gas exchange through their roots (most terrestrial plants do so through their leaves). That means that the potting mix must retain water but remain open and airy so that the gas exchange is not stifled, which suffocates and kills the roots.

Judging by your photos, that relatively coarse bark should stay quite open, so I suggest that you try the following:

1) Take a plant to the sink, and run water thoroughly through the potting medium until it is quite soaked.
2) Let is stand for about 15 minutes or so in order to let the bark swell a bit.
3) Repeat step one.

At that point, the bark should be well saturated, yet open and airy, yet likely will absorb water quite well with a single dousing in the future.

Water again when the pot is dry. This is not done on a schedule, as the drying rate is determined by the draw by the plant and by your growing conditions. It is possible the two pots will dry at different rates.

Those so-called "humidity trays" aren't doing anything but catching drips from the pot.

Oncidium hybrids like it bright, but direct, southerly sun might burn them. If you can move them farther away from that window, it's probably an improvement. The north-facing window simply won't have enough light for them.

I don't have a Sharry Baby, but from what I understand most Oncidium like a lot of water. With bark that coarse I doubt you have to worry about overwatering. If you've only recently potted them in that bark, I would suggest watering at least twice a week, since new bark will hold less water. With ceramic pots it's harder to tell when the bark is dry, but you can test the weight of the pot, it will be much heavier when fully soaked.

As for the light, I have one Oncidium (Howeara Lava Burst) two feet from a south facing window and it does get some direct sun in the early afternoon (supposedly the worst time for orchids to get direct sun, but it has been perfectly happy!), so you may find they don't mind the direct sun. I have another Onc (Twinkle) about 9 feet from the south window, which might not really be enough light. A sheer curtain on that south window if you could get such a thing might be just right, or can you find a little table/plant stand to put a few feet from the south window?

Take Ray's advice. Notice the weight of the newly watered pot, water when it feels lighter. With bark and clay pots, you'll be hard pressed to overwater. I use humidity tray's and I believe they help (some). My Sharry Baby is in an 8" clay pot and sometimes sits in water. This year it had 6 spikes.

Thanks so much for the help! I will water tomorrow morning per Ray's instructions. And I will try to check the pots weight as well as the bark's dryness, but these both sound like things that will take some time for me to be confident that I am doing right.

I used to have a Sharry Baby until I left it outside one fall, and it froze to death. This plant loves water, and in the growing season I was frequently watering it by filling up the saucer it was sitting it, with an amount that would be taken up within 2 days or so. (The substrate was medium bark with some sphagnum mixed in). Once the saucer has been empty a couple of days, I'd water again, but the frequency would depend a lot on the conditions. Every couple weeks I'd give it a good flush at the sink.