Fair warning: Longwinded post because I'm procrastinating as I'd rather analyse and write about plants than analyse academic writing, which is what I really should be doing.
This discussion about troubles with transplanting seedlings has me scratching my head a bit. I went back and consulted my photos, logs and spreadsheet.
My seedling results
Seeds: 94
Germinated: 61 (65% seeds)
Survived first winter: 50 (82% of seedlings)
The germination rate has not been the same for everything:
Seeds bought from Etsy - obesum modern cultivars only: 28
Germinated: 28 (100%)
Survived first winter: 27 (96%)
Seeds bought from Swedish seller - obesum, somalense, arabicum, socotranum: 66
Germination: 33 (50%)
Survived first winter: 23 (70%)
The first winter mortality was mainly due to an infestation of spider mites and my initial lack of understanding of watering requirements in the winter, leading to root rot, particularly in the arabicums and socos as they are slower growers and therefore less thirsty than their obesum and somalense buddies.
So basically, I have had trouble with germination, but once they've germinated, my seedlings have been fine throughout their first spring, summer and fall, including transplanting.
Seeds sown in June had higher germination rates than seeds sown in late March.
Now, I'm well aware that my climate here with indoors growing, plant lights and extreme sunlight conditions with midnight sun in the summer and hardly any light in the winter is quite the mismatch from the climate of most (if not all) people in this forum, so seasons are not comparable, so maybe there's something I'm missing in terms of what we're doing differently in how we grow our seeds. Or maybe I've just been compensated for poor luck with germination by having good luck with transplanting the seedlings. Still, of all the seedlings I've lost, I can't write any of them down to transplanting. Maybe it's just down to the indoors climate being easier to control and not having to worry about rain, wind, pests (as much) or low temperatures.
Either way, I figured I'd share my process of transplanting. Maybe it's the same as yours, maybe I'm doing something stupid as I'm still pretty new to Adeniums with my first seeds sown in March 2021, but maybe there's some nugget in there that might be helpful?
Most of my seeds have been sown either in Root Riot cubes or small individual pots, then transplanted to one pot size up, in some cases two, when they were starting to look a bit cramped in the first pot/cube, usually after about 2 months. Only once did I germinate in a communal pot (a clear plastic food container with lid, creating a makeshift mini greenhouse), and those seedlings were transplanted to individual pots at the same time as the Root Riot ones.
Root Riot germination (IKEA hack double decker because I don't have enough window space):
First transplant of seeds sown in cocopeat, slightly less than 2 months after planting:
(Sidenote: These photos were taken outdoors about half an hour before midnight, July 29 2021. That's about as dark as it gets in summer.)
Second transplant, just under 4 months from planting seeds:
When I transplant them, I remove all the potting medium from roots, getting the last off with a paintbrush to make sure I'll spot any signs of rot and also making sure that if there is any kind of fungi or mildew or anything formed while the seedlings were in a more humid environment, it wouldn't come along to the next pot. Cleaning up the roots also gives me a hint of how each individual seedling is growing. Does it have a long, carrot like tap root or not? Should I mark some for root training?
I did damage some roots a bit when doing the first transplant of seedlings grown in Root Riot. The cubes become this hard-ish mass that is really difficult to separate from the roots without breaking the teeny tiny ones. They all survived, though, even if some of them still have Root Riot bits left on them.
I make sure to have a potting medium that doesn't promote wet feet. I've mixed them a bit differently every time, but some combination of cocopeat, pumice, perlite, sand, potting soil and vermiculite.
One thing I'm very careful with is overwatering. If I would have watered my adenium seedlings like my sweet peas, nasturtiums and sunflowers, they would probably all have rotted. It's so easy to get overly enthusiastic and water them to death. Since it can be quite hard to tell, I got a moisture meter and don't water unless it says "dry". I don't check ALL the pots, but a few here and there, especially the more sensitive ones and the ones that are semi-dormant.
Also, don't give up on the runts! Just because they're smaller or slower than their peers, it doesn't mean they can't grow up nicely.
Look how tiny Tracy was at 2 months compared to the others:
At 4 months (at 21:42 for light reference), she was starting to catch up:
Now she has more branches and a wider reach than any of the others and she is the most frequent and abundant bloomer of all of them.
Okay, I'm gonna stop now and go back to my books. ^^;
