While horticulturalists don't consider rosemary and basil as companion plants that benefit each other, they safely coexist in your garden. Both rosemary and basil add flavor to salads, sauces and main dishes. Plant rosemary and basil together in an herb garden or in pots next to the back door to quickly season meals. Basil needs a bit more water than rosemary, but both thrive in full sun. Grow frost-tender basil and rosemary as annuals in cold climates.
Herbs, such as rosemary and basil, do more than season meals. Many flowering herbs attract beneficial insects that eat lacewings and aphids. Herbs often have unusual foliage or flowers and scent the air with their fragrance. If you lack space, tuck rosemary and basil into perennial beds or grow them in containers. Plant an herb garden alone or in a vegetable garden. Most herbs need full sun and moist, well-drained soil.
Rosemary produces small, stiff leaves on woody stalks, while basil produces succulent, tender leaves on soft stems. Pull the needlelike leaves off rosemary plants to use with roasted meat dishes or in potatoes. Rosemary has an arresting, savory flavor and a little goes a long way. In fact, rosemary is toxic in large quantities, according to "The Herb Identifier." Pinch off basil leaves, wash and use them whole or cut them with a sharp knife. Basil has a fresh, mild taste. Use it liberally to add color and flavor to pesto and bruschetta.
Start basil seeds indoors four to six weeks before the last frost or sow seeds directly in the ground in early summer. Buy slow-growing rosemary plants from nurseries rather than starting them from seed. Plant both herbs outdoors only after daytime temperatures are above 70 degrees Fahrenheit. Water basil and rosemary to keep the soil evenly moist. Pinch back basil if it starts to get leggy or produce flowers. Harvest basil and rosemary before the first frost or bring the plants indoors for the winter.
Storage and Use
Cut rosemary and wrap small bundles with a rubber band. Place the rosemary in a brown paper bag and store it in a cool, dry location for two weeks. Once dry, rub the leaves off the stems and store in a dry container. Use dried rosemary sparingly as the flavors become more concentrated. Basil can be dried using the same method, although it loses its fresh, appealing taste during the drying process. Make and freeze pesto to use extra basil or freeze the basil leaves alone. Frozen basil leaves retain their flavor, although the leaves darken.