Watering depends on your growing conditions. I have my jade outside (in shade from 11:00 AM till 4:00 PM), in a greenhouse (which during the summer months will often get up to 110 F even with a large fan running and the doors/vents wide open), and a large plant on a porch where the plant gets about 4 hours of early morning sun. The ones outside get watered when my in-ground irrigation system is running and when it rains. These plants get more water (by far) than the others that are indoors. Needless to say, the ones in the GH dry out really fast and the ones on my porch moderately fast. Those are the ones I will occasionally do the submersion on. I submerged them yesterday in fact. Like you, I am using an almost "desert" mix that drains rapidly and retains only a bit of moisture. I try to water my greenhouse/porch plants every week, and I am watering them heavily. But when they are neglected and show those shriveled leaves, it is submersion time.
Yes, I completely submerge the plants, though the large ones might be tall enough that the top 1/3 of the plant doesn't get submerged. The tub is approximately 30"x18" and 12" deep. I have actually left plants submerged in the tub for an hour (I get busy with my other plants
) but when I remove them and let them drain, all the water is going to run right out. I have never lost a jade plant as far as I know. The tub might be impractical for many, but since I keep one filled with water outside one of my greenhouses just for this purpose, it is handy for me.
