Why is my Adenium obesum wilting?

Question

This desert rose, Adenium obesum, was put on a window sill on top of a radiator, and did well for approximately 10 days.

Then I left for the Holydays. I left the plant with extra water and no heating. The temperature must have gone under 10ºC, (50°F), but it wasn't watered any more during my absence of 15 days.

On my return, as you can see in the pictures, I found it wilting.

I thought it might be a watering problem, as the soil was completely dry, so I watered it, making sure all the water drained. I also moved it to a window sill where there is no radiator. Now the roots are moist, if I touch them from the bottom holes of the pot.

The soil is clearly peat based, and it looks like the bottom is moist, but the top quite dry. What should I do? Water it more? Leave it without water for a while? I really have no idea!

My house has a temperature of approximately 15-16ºC during the day, sometimes 17-19ºC when I turn on the heat at night. The aspect of the window is south-west, but it doesn't get much direct sunlight, about 3-4 hours when it's sunny. I am in the UK, Bristol.

Answer 1

Adenium obesum is a succulent. Like most succulents, it needs very little watering and will suffer if over-watered. These problems can be made worse if the soil is not a rapidly draining medium. You say that the soil appears to be peat-based, which is not good for a succulent. Peat helps to hold moisture in, which is the opposite of what a succulent needs. A little peat is okay, but high peat content is not. I suspect when you gave it 'extra water' before leaving you over-watered the plant causing some of the roots to drown. This particular plant also doesn't like going under 10 degrees C, so if the temperature dropped enough that may also have caused some injury.

I would suggest re-potting the plant into a cactus/succulent potting mix, watering less frequently and keeping it off the radiator.

Answer 2

It may have outgrown its pot. Perhaps take it out and see how densely packed the roots are.

Answer 3

If it's on a window cill, maybe the temperature immediately around it is colder than you imagine. Your room temperature maybe one thing, but if it's placed behind curtains it will be considerable colder. We've had temperatures to well below 0'C in your part of the U.K., I'm within about 50 miles of you, so have been aware of local temps.

Answer 4

I don't think it needs a new pot. The soil could be an issue. I suspect that it probably got cold. They really don't like temps under 50F. If it's cold for a short period (a few hours) the leaves will droop then drop off. It will make new leaves in the spring. If it's cold for longer, the leaves will drop and the stem/caudex will get soft. Then it starts to collapse.

Does it feel soft when you test the stem/caudex? The body can be a little soft when it hasn't been watered for a while. Normally it's firm like an apple. If the soil is damp and the body is soft you should probably deal with the soil sooner than later. If you suspect sub-soil rot, take it out of the pot. It can stay out of the pot with filtered sun for several weeks.

One other note, the plant does look etiolated which will make the drooping more pronounced. I grow my plants outdoor (except for the winter) and the node spacing is very short. The node spacing on your plant looks to be over an inch.

If this were my plant, I'd water it sparingly until spring, assuming it's not damp AND soft, monitor it to see if any other problems pop up. Repot it in the spring with more appropriate media and prune it. Give it a few weeks before watering then continue as before.

Other than cold, they are pretty robust. Good luck!