Any of the ‘woody’ herbs are hard to start from seed. Professional greenhouses and nurseries propagate those plants from cuttings.
It CAN be done, but you need the patience of a Saint! Please remember; Burpee IS trying to sell you seed, so they will make it sound easy. It is not.
https://www.burpee.com/blog/how-to-grow-rosemary-from-seed_article10491.html
As for the plants you have already, I am having great success this year with Rosemary I’ve brought indoors because I finally figured out that they need to be sitting in a tray of water for humidity, and they need weekly misting as well as weekly watering. And a south-facing window or supplemental light from a grow light.
This is the first time in my long ‘career’ of trying to over-winter Rosemary (In Zone 4/5) that I’ve had any success.
And I are a Paid Perfeshinal! :)
Rosemary is being planted everywhere where I live as hedging - saw this in Northern California too - it has beautiful small blue flowers and smells wonderful. It also attracts bees - a lot of them, and I suspect this is why it is being planted all over the place.
Neighbor says she comes out to the median and picks a few sprigs when she cooks lamb chops for her husband. He told me later it is his favorite dish.
This is great - I DID decide of my own free will to try to grow rosemary from seed. The one that’s still alive, it might be trying to root - I’m just kinda spritzing it with water once a day or so - and that’s why I just haven’t started over by now. This is high altitude (8600 feet above sea level) and so if you have a rosemary plant you just set it in the window or on the stairwell and outside when it’s above 60 degrees. In a really big planter.
Thank you so much! 🥰