Hi all,

I am new to this forum and a complete noob in plantology.

Last week I have relocated to beautiful Los Angeles and added two plants to my living space - a Mexican fence post cactus and a dumbcane, as you can check out the pictures below.

Like many amateurs, I thought cactus can withheld high heat thus I left it be for a week on my patio. Later I found out it's got (I am hoping) sunburnt and I do not know what to do. When it was at the nursery it was getting a more gentle sunlight from a shaded area. I called the nursery where I got it from and he said to cut it off as it is dying. But I have also done numerous hours of research that I am quite sure it isn't a fungus disease. The plant still feels firm rather than soft and mushy. And the black/brown spot are where the plant got hit with direct sunlight the most.

Can someone kindly ID it? Below are some pictures of the damage. I have left the cacti in a more shaded area for now before I decide to do any surgery with it. Also a bit concern on the bottom, upon panicking my girlfriend decided to water it last night (first water since we got it) though it still feels firm, the colour seems darker than most of the plant. Can we still save this plant?

Much appreciated!

-Eric

It does not look good, but I wouldn't give up right away. If the plant does recover, it will be really scarred. It will need protection from the sun and/or heat (to the extent you are inland and summer is not a breezy, foggy experience like it mostly is here). Bright light is important but direct sun should be limited to the morning hours, not mid day. Filtered light or brightest shade will work too. Not deep shade.

As a general rule you have do do a gradual stepwise accommodation to the sun when you get a new plant. Assume it was growing in a greenhouse or under shade cloth unless you can confirm with the nursery on the spot that it's been adapted to the sun.

Usually this means a few weeks of moving the plant each week to a slightly more exposed location. Three notes about sunburn: (1) the sun is most intense energetically around the summer solstice (ie. right now); (2) the most intense sun comes at mid day, so overhead protection or shade cloth can be very useful to block or filter those rays; and (3) heat makes plants more vulnerable to sun.

At this point you have to exercise restraint with the water. Always wait for the soil to go dry at depth (not just the surface) before watering. There is no particular advantage to allowing it to sit bone dry for any extended period, but there is an increased risk of rot if it does not dry out enough often enough.

Be aware the soil will go dry slower when a plant is in crisis (not drinking deeply) and when it is receiving shade protection.

Baja_Costero said:It does not look good, but I wouldn't give up right away. If the plant does recover, it will be really scarred. It will need protection from the sun and/or heat (to the extent you are inland and summer is not a breezy, foggy experience like it mostly is here). Bright light is important but direct sun should be limited to the morning hours, not mid day. Filtered light or brightest shade will work too. Not deep shade.

As a general rule you have do do a gradual stepwise accommodation to the sun when you get a new plant. Assume it was growing in a greenhouse or under shade cloth unless you can confirm with the nursery on the spot that it's been adapted to the sun.

Usually this means a few weeks of moving the plant each week to a slightly more exposed location. Three notes about sunburn: (1) the sun is most intense energetically around the summer solstice (ie. right now); (2) the most intense sun comes at mid day, so overhead protection or shade cloth can be very useful to block or filter those rays; and (3) heat makes plants more vulnerable to sun.

At this point you have to exercise restraint with the water. Always wait for the soil to go dry at depth (not just the surface) before watering. There is no particular advantage to allowing it to sit bone dry for any extended period, but there is an increased risk of rot if it does not dry out enough often enough.

Be aware the soil will go dry slower when a plant is in crisis (not drinking deeply) and when it is receiving shade protection.

hi there thanks for the comment! should i just leave it in a shaded area without cutting off the black part/tissues for now?

Yes.

I concur with all Baja's advice, but would like to add that the nursery did not do you any favors, this plant can take all day full sun in the Phoenix area, so growing it in any kind of shade in the LA area is really setting the buyer up for failure, on top of that they should have given you a south facing marker on the pot so you could orient it the same way, which would have helped with the sunburn. Given how one sided the burns are, which could just be due to how it was exposed at your place, but it could also have been caused by having the north facing side from the nursery facing the dominant sun side on your patio.

I would only cut if the burn does not stop spreading now that it is out of the sun.

mcvansoest said:I concur with all Baja's advice, but would like to add that the nursery did not do you any favors, this plant can take all day full sun in the Phoenix area, so growing it in any kind of shade in the LA area is really setting the buyer up for failure, on top of that they should have given you a south facing marker on the pot so you could orient it the same way, which would have helped with the sunburn. Given how one sided the burns are, which could just be due to how it was exposed at your place, but it could also have been caused by having the north facing side from the nursery facing the dominant sun side on your patio.

I would only cut if the burn does not stop spreading now that it is out of the sun.

noted thank you sir. i will wait a few days. if it spreads i will separate the tip and perhaps grow it in a different pot.