Plants I killed

As growing houseplants in semi-hydro is an experiment and there are tons of things I don't know or understand yet, I managed to kill quite a few plants. But I've learnt from my mistakes every time.

One plant that died on me was a Calathea albertii. It was a salvaged plant from clearence shelf. After repotting it bounced back nicely but then started losing old leaves. However, new shoots sprouted. The plant lived for a good 3 months but kept dying back. I couldn't seem to find the reason why. Then noticed tiny white and black powdery things on the back of the leaves that didn't respond to any treatment I tried so had to get rid of the poor thing before the didease spread to other plants..
Calatheas can be finicky. I am having problems with a zebrina and a roseoptica at the moment (maybe dry air due to heating, will try to bag them for the rest of the season).

Another loss is a Haworthia pentagona that collapsed a few days after I transplanted it. Maybe got too wet while I removed the soil from the roots. It never seemed to mind the showers though.

I learned that ferns don't especially like direct sun and semi-hydro. I am lucky with my Asplenium nidus as it is doing fine but not as lucky with Polystichum tsus-simense aka Korean rock fern. It simply dried out beyond saving in a few days time on the windowsill. I was too careless I believe.

The mango I grew from seed got a bad thrips infestation. The avocado seeds didn't even sprout, maybe it's best to root them in water

I don't know anyone who hasn't killed a plant yet - by accident, by carelessness, by incompetency or other reasons. So don't be sad if you fail once or twice, next time you will be more careful.