Pseudolithos mccoyi was hard for me for a long time. First one I got was DoA, second one withered into nothing in too much sun. Third one is still alive, less than 10% direct sun, 75-100 degrees Fahrenhei, constant air circulation, and high humidity have caused a huge growth spurt. Anything from tropical coastal deserts are kind of hard to grow, because they like a strange mix of relative dryness and humidity in my experience.

Senecio scaposus var. addoensis is the only plant I have given up on so far. Very strict dormancy in Florida. I had had it for 2 weeks, and it got caught in a single rainstorm and was completely dead by the end of the week.

Dorstenia buchananii var. longepedunculata, I was giving it a strong drink every week and a half and I had substantial stem growth. Got caught in the sprinklers one night for 10 minutes and the stem base rotted upwards and down into the caudex. I didn't notice until the stem started sagging. I tried squeezing the caudex and the insides of it oozed out :-(

Pseudolithos cubiformis also got caught in the sprinklers that same night. I had to cut off its largest lateral stem because of rot less than 24 hrs later. It's still alive though! :-)

Aeoniums are a challenge to me. I imagine they are easy to grow, but so far I've been doing something wrong and I've killed several. Knock on wood, I have one right now that isn't dying!

Euphorbia susannae and Euphorbia obesa for me. I don't know why, just dies. I have trouble with Pachys too. I think I need to be much harsher to them over the winter than I am (water wise). I've gotten some other Euphorbs that instantly died (were from a mail order). But I think it might have been a discreet error on my part.

I'm with Ben. Particular species of Dorstenia and Pseudolithos have given me a lot of trouble. I think I'm on my third or fourth Dorstenia gigas. I can usually keep them alive for a year or two, but they don't grow at any appreciable rate. It's July now, and my current plant is still not growing. I'm hesitant to give up because it's such an amazing plant, but they may simply need more heat and sun than my climate provides.

Pseudolithos cubiformis is one of my favorites, but they also rot quite easily. I currently have 3 seedlings after losing one just last week. At least I can get these to grow, but you have to be very careful about rot.

-Chris

edithcolea grandis was fine one day and mush the next. Wanted to see its flowers but oh well

I kill semperviums all the time. They are easy to grow, but seems like I can't keep one alive.