I've only grown New Guineas from plugs so I'm not familiar with the seed grown variety. I did find some 'grower facts' from another seed company, however. Click on the attached link, then click on the 'grower facts' to open a pdf file.

Here is a link that might be useful: New Guinea Impatiens from seed

It has been years since I grew a run from seed instead of rooted cuttings and that was when the first commercially available line came out......Tango.

I notice that some new lines are now available and that could change the equation a lot. Growing seed-start NG imps are a little more challanging than yiour buzy lizzies. First off is the longer production time to reach the size you'd expect to buy them if they were sold potted. Under ideal conditons we are talking six to eight weeks to size up. I found them to be more sensitive to growing conditions, especially in regard to growth and proper exposure and watering. They can sit for a long time at a squatty size and will lose their precious leaves if they feel insulted. LOL. I can't complain about how they did eventually when planted outside in my trial beds but it took a lot time for them to kick in compared to those I started from rooted cuttings, and considerably longer to come to bloom.

I still think cuttings are the easiest way to go, however, I doubt you'll find any on the market not patented and you can't take cuttings off patented stock. If you have ideal conditions under which to grow them it would be tempting to try it, especially with the new seed introductions. Some seed-grown annuals tradtionally offered only by cuttin are as good or even better than the old varieties. I love the anelonia "Serena" series for example compared to the cutting grown plant. I switched over to it.