

Pelargonium cuttings ready to move to soil
Pelargonium scabrum (left), and Pelargonium glutinosum (right), with two of the rooting mediums which I typically use: either just perlite, or a mix of perlite and coconut coir.
I do also use more of a soil mix (for ones that respond well to it), but I usually start with either one of these first. I generally avoid any compost at this stage, because it holds on to water for too long.
P. scabrum cuttings I have found to be quite easy to root, with minimal losses.
I have tried rooting P. glutinosum cuttings previously, and it didn't go well. I usually remove cuttings when I see any signs of yellowing (as you can see along the stem in the second image), however the new growth on this one looks fine so maybe it's okay? If the new growth looks yellow/brown and wilted, I don't even bother.
One thing I have noticed is that you should be mindful when top watering when your cuttings are cut on top (pic 2). If there is water just sitting on your cuttings, it can promote fungal issues and infections. Which is why I really try to maximise air movement to speed up the evaporation of excess water. You can also bottom water. When I start cuttings indoors, I'll usually put a fan on to just move air around gently. Otherwise just outside, away from direct sun.
Or just use tip cuttings (as is typically recommended), however tip cuttings can sometimes be too tender/soft/bendy which usually results in failures. You're looking for new growth (not older woody growth), but not too tender either, so you may need to take your cuttings a little lower down in these cases.