(Preface: I'm not sure whether this will be of any interest to people other than me, but what the hell. Saturdays tend to be slow blog days anyway, and I've gone to the trouble to make graphs and spreadsheets so I may as well use them. Don't feel compelled to care.)
I have, at the moment, 725 plants. Officially. I actually have more than that, but they're not mature enough to count (seedlings, cuttings), not in containers and/or not indoors, part of Nina's terrarium, or otherwise not quite ready for prime time.
Besides those 725, I have had 484 more over the last three years, which are no longer with me for one reason or another, for an overall total of 1209. Here's what happened to the 484 missing ones.
230 of them were sold, traded, or given away. Most of these were specifically propagated for the purpose of selling/trading/giving, and don't really count as being dead, though I'm sure a good number of them probably are by now.
One plant was thrown out because I was impatient for it to do something. It was a pineapple (Ananas comosus), and probably was actually rooting, but it wasn't doing so quickly enough to suit me. I think lack of space was also a factor.
One plant (Adenium obesum) was thrown away because it went dormant and I thought that it was going dead instead. My bad.
One plant (Rhapis excelsa) was divided at the wrong time of year, and of course I couldn't get the division to root.
One plant (a Begonia) was getting too much sun, and burned up before I realized that that was its problem.
Two casualties I blame on a combination of being overpotted and having bad soil.
Two plants were rooted in water but then failed to switch over in a timely fashion to growing in soil.
Three plants are just perverse and impossible to please (Fenestraria rhopallophylla, Philodendron 'Xanadu,' Streptocarpus 'Purple Martin'), and I never had a chance.
Three plants were discarded because something fell on them, or they fell off a shelf, and broke in an unsalvageable way (though in one case I was secretly glad about this: I didn't like the plant anymore, but had no good excuse for getting rid of it until The Accident).
Four were lost to fungal infection.
Five were cut back at bad moments and failed to come back from the pruning.
Five were transplanted too early, or in the wrong season, and died as a result.
Seven died of insufficient light, or more accurately, they died because of being ugly, because of insufficient light.
Nine were lost to spider mites, though usually spider mites weren't enough without some exacerbating factors (dry air, neglect, being a croton) to push them over the edge.
Nine died due to unknown causes: either I just didn't record a cause, or I couldn't figure out what to blame.
Ten were already in bad condition when I made them official plants and just failed to get any better; most were rescues.
16 plants were thrown out due to mealybugs. I have, on occasion, actually tried to fight mealybug infestations instead of pre-emptively discarding the affected plants, and sometimes this has even worked out, but it's rare enough that I no longer automatically try to save the plant. The overwhelming majority in this category are Haworthias, because I got one plant that had mealybugs, noticed the mealybugs and tried to divide it so I could at least salvage a couple offsets from the situation, and counted the divisions as plants. Even with squishing all the adult bugs I could find and dunking the divisions in rubbing alcohol, I still found bugs on the offsets mere days later, so the one plant with bugs got counted like nine times. Also quite a few Marantas in the mealybug group.
21 were simultaneously overwatered and underwatered. Saintpaulia ionantha cvv. owns this category: I'd let them get too dry, realize it too late, and then try to overcompensate by standing them in water, which I would then forget to dump out.
21 were overwatered. Crappy soil was probably a contributing factor in some of these, but I'm more than capable of overwatering a plant even with good soil.
30 involved me putting a cutting or division of a plant on the official spreadsheets prematurely, and then having to count it as a fatality when it failed to take.
39 plants were underwatered. When I say I'm not good at plants that can't occasionally cope with the occasional long drought, I'm being totally sincere. You'd think that the plants would know this by now, and stop jumping into my arms in the garden center.
64 were thrown out because they were ugly. This was often my fault to some degree or another, so there's a bad-care aspect to most of these too, but plants in this category, though they probably could have been rehabilitated back to respectability, never did that much for me in the first place, weren't in good enough shape to sell or give away, and were taking up valuable space that could have been used by something else.