Help with New Natal Plum (Carissa macrocarpa)

[NaturalArt]

I purchased this adorable natal plum pre-bonsai stock from my nursery 2 days ago. The only thing that I have done with it so far is give it a humidity tray with aquarium stones and place it indoors in a western facing window. I live in Colorado so it will likely not get moved outside until end of April or May. I haven't even watered it yet because everything I've read online about care has said that it likes to have a period of dryness since it is very susceptible to root rot, and the first inch of soil is still very damp to the touch (when I picked it up from the nursery it was SOAKING wet).

My concern is that today I noticed a fine white substance on the surface of the soil, reminding me of mold (pictures attached). What should I do? I know it will need to be repotted at some point as the roots are circling the bottom of the pot, fortunately the visible roots look healthy and the tree still looks happy (I purchased it with the few red leaves). I have not opened up the root ball to investigate as I was going to wait until the end of winter/ early spring to repot. Should I repot sooner if that is mold? I do not know what kind of soil it is currently planted in but my guess is that it's very organic. I have bonsai soil mix made up by my nursery that I was going to use down the line to repot with.

Obviously this little tree still has a lot of development to do and I was to allow the trunk and nebari to thicken up, I was thinking about leaving the lower most branch as a sacrifice branch, but I would love to hear some opinions. When I repot it should I transfer it to a larger pot (with or without the sacrifice branch)? If so what size pot would someone recommend? I would prefer to stay away from planting it outside because from what I've gathered this plant is very temperature sensitive and Colorado is very temperamental about temperature.

Any other suggestions would be greatly appreciated!

Thank you!

 

[Leo in N E Illinois]

Actually, I would not worry, you natal plum looks reasonably healthy. The fungus is probably not pathogenic. It might be mycorrhizae, but more likely it is just a run of the mill non pathogenic soil fungus that took advantage of the overly wet soil. It should ''disappear'' when the soil dries out.

Natal plums like to go from wet to just about dry, or be dry for a day, then watered again. You don't want to leave them dry too long, or new growth will stop. The soil it is in does not look bad, it looks nice and coarse, good air voids, which is why the roots seem healthy even though it was very wet. You might want to top up a bit with your bonsai mix. Keep the surface roots covered. You are correct, it is best to repot in spring. You can wait until then to repot.

If you can, summering outdoors, keep it in a pot, or a bonsai pot, but put it outside on a shelf, bench or other spot off the ground. It will enjoy the sun in summer. Colorado does have wildly varying weather, so it probably won't be outside all that long. Best to avoid frosts and freezes with Natal plum.

 

[Bonsai Nut]

Think of it like a succulent and you won't go far wrong. They do not need humidity, so I wouldn't worry about water in the humidity tray. They grow just fine in the landscape here in Southern Cal, and once established need very little supplemental watering. Your tree's leaves are lighter green than they should be, and I see a little fungus on some of them. All lead me to believe this tree was being overwatered and kept in too-humid conditions. This is what a healthy one will look like:

 

[NaturalArt]

Actually, I would not worry, you natal plum looks reasonably healthy. The fungus is probably not pathogenic. It might be mycorrhizae, but more likely it is just a run of the mill non pathogenic soil fungus that took advantage of the overly wet soil. It should ''disappear'' when the soil dries out.

Natal plums like to go from wet to just about dry, or be dry for a day, then watered again. You don't want to leave them dry too long, or new growth will stop. The soil it is in does not look bad, it looks nice and coarse, good air voids, which is why the roots seem healthy even though it was very wet. You might want to top up a bit with your bonsai mix. Keep the surface roots covered. You are correct, it is best to repot in spring. You can wait until then to repot.

If you can, summering outdoors, keep it in a pot, or a bonsai pot, but put it outside on a shelf, bench or other spot off the ground. It will enjoy the sun in summer. Colorado does have wildly varying weather, so it probably won't be outside all that long. Best to avoid frosts and freezes with Natal plum.

Thank you very much for the reply!
I'm glad to hear it's nothing bad, should I wait until the soil is more dry to top off the surface, or is it okay to add it now?

 

[NaturalArt]

Think of it like a succulent and you won't go far wrong. They do not need humidity, so I wouldn't worry about water in the humidity tray. They grow just fine in the landscape here in Southern Cal, and once established need very little supplemental watering. Your tree's leaves are lighter green than they should be, and I see a little fungus on some of them. All lead me to believe this tree was being overwatered and kept in too-humid conditions. This is what a healthy one will look like:

View attachment 222558

Thanks for the reply, and that is a gorgeous plant!

Over-watering is absolutely my suspicion as well, when I picked it up at the nursery I had to drain out a significant amount of water from the pot (while narrowly avoiding getting water all over myself lol), so I think not only was it over-watered but it was left in standing water. I'm hoping with a proper care routine that it will bounce back quickly.

 

[Carol 83]

Give it as much light as you can, indoors. . My natal plums are the only trees that don't react at all, when brought indoors for winter.