Mold or precipitate on houseplant soil? Yellow peaks in soil clump tops

Question

Ever since I got my 2nd hand dragon tree, the soil has had these yellowish peaks. Until today, I never really thought about them.

However, I added some new soil on the old about a week ago. The yellow peaks seem to be already appearing. It is also on the ceramic pot.

So far I had attributed them to calcium deposits from evaporation, but Google rather proposed yellow slime mold. I have never seen any real fungal activity in the pots.

This happens also in the 2nd generation of the plants, i.e. with cuttings.

Here are a couple of photos from a pot where some cuttings are growing.

What do you think these yellowish things are?

Answer 1

These are mold or fungi that are eating the organic matter in the soil less mix which will have a higher percentage of bark and peat than soil in the garden.

All they need to get going is wet soil. They do no harm to the plant.

You can use a chopstick or old fork to break up the top of the soil and try and keep the plant a little drier. Dragon tree or Dracaena reflexa var. angustifolia (Dracaena marginata) is easy to overwater and best cultivated with more light and less water

Answer 2

I just showed my plants to two professional plant caretakers. They said that it certainly is not mold/fungus, but precipitate. Mold or Fungus would also have a distinctive smell.

I also saw a while ago some other dragon trees with the same precipitate.