Water rosemary plants evenly throughout the growing season. Once they develop flowers, trim the plants regularly so that they do not become too lanky. During the winter, keep rosemary plants indoors in pots and expose them to plenty of bright light.
The best time to plant rosemary is in the early spring, about eight to 10 weeks before the last frost. The soil should be around 70 degrees Fahrenheit when you plant the seeds or cuttings. Seeds should germinate within 14 to 21 days after planting, and you can transplant them outside when they are a couple of inches tall. Rosemary plants grow up to 4 feet wide, so allow them adequate space when planting.
Rosemary thrives when planted in an area that receives six to eight hours of sunlight each day. This herb also prefers soil with good drainage. You can apply a basic 5-10-5 fertilizer during the spring if you prefer, though there is little need to fertilize the plants.
You can harvest rosemary slowly throughout the summer. Remove small sprigs of the plant with scissors and hang them in a warm, airy place to dry them out. Discard the stems before using the leaves in any recipes.