Prosthechea brassavolae pseudobulb went squishy
 

My concern is that today I noticed the second newest pseudobulb had gone squishy and folded under the weight of the leaves. Why could this be? I considered dehydration, but its not very wrinkly and still bright green.

Its a relatively new orchid that I received a few months ago. It's growing new roots but they aren't long enough to absorb water yet.

I ended up losing the last Prosthechea I had (a P fragrans) to fungus, so I'm a bit extra paranoid for it.

How are you watering these? Fungus is unlikely if you are growing them with typical home relative humidity.

Turns out it was dehydration after all. I started growing it constantly wet after I posted this and the bulb hardened back up.

I'm kinda surprised. Everything I've read said they should dry out before watering again and that they even need a winter rest.

When people say to let Cattleya types dry out between waterings stems from advice given to beginners to avoid root rot. If the medium is airy or chunky enough then you could water Cattley types every day and they would thrive. Water doesn’t rot roots, lack of air does.

Edit : A note about the rest, do not keep it bone dry like you would a Catasetum, instead you should let it dry between waterings, maybe watering around every 2 weeks with some mistings in between. Although there is no rain during the dry seas there is still heavy dew and high humidity and the plants are never dry for months on end. Not watering will shrivel the bulbs severely and possibly kill the plant outright.

Edit 2 : No fertilizer during the rest either.

Many of us found out the hard way Prosthechea and Anacheilium want to stay between wet and moist. I now use S/H for them, or if in bark stand the pot in a shallow dish of water. I think sphagnum would also be great for them.

If potted in bark or sphagnum, the medium will age rapidly, and repotting will be needed every 1-2 years.