No roots after 4 weeks?
It's a mix of regals, zonals and angels;
Temperatures remain above freezing year-round over here, and it is a practice to sow seeds in the fall. (Mediterranean climate)
The book "Geraniums - The complete encyclopedia" by Faye Brawner states that rooting hormones are not necessary. I took cuttings in early spring (Around February) and success rate was good. My collection was growing steadily and I decided to take advantage of the cool weather of March. April is still colder than average this year and this might give me a week or two of mercy to try and practice my propagation skills.
The cuttings I took in March were not better than plastic plants: They looked the same! It's more than three weeks. I occasionally took the soil clump out to examine the root and find none. After waiting, I decided to scrape the soil. A few were infested with stem rot, as you might have expected. To my surprise, I find that most stems remained green and they seem to get all their humidity through the cutting area rather than setting new roots. The did not wilt, but they did not root either.
The exception was P. Sidioides. This one seems to root within a week, even when the air is hot.