I think the best way to think about a plant and what it needs is to find out what the conditions are where it grows natively. I think that the holiday cacti are from various high coastal forests in Brazil, where they grow in collected debris. So I would opt for a more fast draining chunky soil than the MG. Many people use a lot of bark in their mix. Also, I would think about how the temperatures and humidity changes in your home over time. I think that since these Brazilian forests are at high altitude they are cooler than it is in summer in most of the US, and certainly more humid than it is where I live, even in summer. So even if your care hasn't changed over the year, the conditions probably have. I also think that holiday cacti are plants that like more neutral towards the acid side for soil pH. So if you have been watering your plant for a year in a soil that doesn't drain well with water that is on the alkaline side like mine is, that can change the conditions that your plant is experiencing over the year, or even just since April. Anyway, I would use a chunkier soil with bark in it, I would keep the plants as cool as I could in the summer, and make sure to water them in such a way as to let the water run out the bottom of the pot and not collect around the roots.

The segment at the soil line had rotted and could no longer support it's branch. What could this be.

This may have started in the older soil as well, moisture may have been standing ( perched) on the soil surface for to long

I like the plant theology from a seed is a promise as well. My experience with the suggested bark mix of five years for my EC and 2nd season recovery of a TC has not been a disappointment.

I agree with the preceding posts, but would like to add something to consider.

Often, trying to replicate the growing conditions where a plant is found can be a well-intentioned error. For instance, many plants (like peace lily) found in riparian settings do very poorly in containers when the grower tries to replicate that setting. Plants found in sandy or clay soils also usually suffer in containers when that type of soil is used. Containers are so different from growing in the ground that in virtually all cases, the soils chosen for container growing need to be radically different than soils where the plant naturally occurs ...... which brings me to another point.

Where plants naturally occur is not a good indication that they actually prefer that location. In a perfect world, each plant would have it's own little plot of ground where it could grow unencumbered by competition from it's neighbors. A very large number of plants occur in areas that are only marginally suitable for their existence, simply because on sites where they could and would grow better if there was no competition, they are out-competed by more vigorous species and are thus relegated to existing on fringes or marginal sites that allow them, but not their competitors to survive.

Al

Great points to consider, Al!

With these jungle/holiday cacti, I have found that the bark-based mix is superb. The durable bark provides good anchorage for roots, and also holds little water when screened and potted appropriately...allowing for thorough watering and regular fertilizing without issues related to perched water or salt accumulation.

Josh