Rosemary is a fiddle to grow from seed.

It is a tender perenial and it is best to get good quality nursery seedlings and plant in situ where they will get full sun with possibly some afternoon shade.

You will need to leave a good 2 feet (60cms) around the seedlings for them to thrive. (we didn't leave enough space in the herb spiral for it and after a great start it didn't thrive. It didn't really matter - I had heaps of rosemary elsewhere in the garden!. I did have enough in the spiral to use - waste not, want not)

Rosemary will grow in fairly average soil with a ph of 6.5 to 7, but does need good drainage.

Growing rosemary near cabbages and beans will repel moths and beetles

check out growing rosemary in a herb spiral

PS Since writing the above the rosemary bounced back into live again, as did the marjoram which was next to it. I suspect they both got too much water - maybe a function of where they were on the spiral relative to my watering system.