What kind of soil does rosemary need to be planted in?

Give rosemary as much sun as possible and water sparingly. It can take regular watering but doesn't tolerate sodden soil.

To this end a sandy, lean loam is best. Sandy loam has no more than 20% clay with at least 50% sand and the remainder the intermediate silt. For a lean soil you need less organics mixed into the soil but a top layer of wood chips or other coarse mulch will help retain water in the soil during dry spells without adding to much winter water retension.

Harsher conditions like periodic drying and low fertility can make herbs concentrate their fragrant oils. It grows best in neutral soil between pH6.0 to 7.0.

Mediterranean plants are well adapted to hot dry summer drought periods but they do not grow well in winter wet soil. So if you have a lot of clay to retain water the soil will need to have coarse sand or fine gravel added to increase drainage in a large enough area for the cultivar you have. Rosemary that is grown in wet soil during winter cold will stand much less chance of surviving.