Try setting the temperature at 25C (77F) of the germination flats. I read someplace that both are fussy about germination temperature and after doing this my results dramatically improved. I also have noted germination time to be anywhere from 15-30 days for both. The New Guinea Imps I sowed was fresh seed but even so only got about a 65% germination rate.

Good luck and show us some pics when it happens

SCG

Thanks SCG for your input! Troublesome green algae starting to form on these flats........ Great.....

When (if?) it happens, I'll post some pics......

Okay, so I sowed some geraniums 'Maverick series' and 'Summerbreeze Ivy' Feb 6 evening and have 50% germination this afternoon. Soil temp was 25C and I rolled them lightly on 320 grit sandpaper to try and scarifying them a bit. Don't ask me why.

Fastest I have ever seen. The begonias are still hiding on me.

Hope your getting some success.

SCG

Day 16 & no joy here........ Unless growing bright green algae counts.... I had sowed 30 Pets in the same flat as begonias & they germinated in 4-5 days from three year old seed...... Go figure...

Tried to pot up the Pets to get them off the heat mat & it appears I've lost most of them.......

Most of my annual beds require shade annuals so I'm pretty bummed out..... I'll give Coleus a try here shortly...... With a LFD of May 5Th, I'm running out of time....

I am out of impatien seeds (don't do well In my gardens) but have coleus 'pastel wizard' 'black dragon' 'versa lime' and 'sun watermelon' seeds off the top of my head if you should need. But don't quote me on names or availability.

Thankfully I always start new varieties early as I am having a mouse eat my seedlings. Haven't caught it yet but protecting the expensive geranium and petunias!!!! Would have sucked to have it decimate flats of flowers

Let me know if you want coleus seed..

SCG

Hi, I am in the UK and I think I have finally mastered the art of germinating semp begonias
I started my sowing towards the end of November, I seived the compost and filled my tray then soaked it in warmish water and left to drain in the propogater set at 75. The following day I gently compressed my compost, I then gently scattered the minute seed over the surface, Gently misted the seed and Sealed with a bag, 10 days later there was about 90% germination I then left the bag off and placed the container close to the light and dropped the temp to 70
That was 11 weeks ago and the seedlings are now ready to start pricking out,
Hope this helps. Begonia do require a long growing period.

ron.j that is interesting as every time I grew them in bags if I didn't harden them off to come out of the bag they just disappeared. I shall try again LOL