Plant the rosemary in sandy soil with good drainage. According to Gardening Know How rosemary plants are difficult to germinate by seed, but will grow from cuttings very easily--take a fresh cutting, and place it in a mixture of peat moss and perlite, keeping it moist until roots form, then plant it.
Place the rosemary in a sunny spot--rosemary plants need around 6 hours daily, so if you are planting in the garden, this needs to be taken into consideration. Rosemary plants also need warmer weather, given that they are Mediterranean natives. If winters in the area reach below 30 degrees Fahrenheit, plant the rosemary in a pot so that it can be moved indoors during winter.
Water the rosemary only once the soil is dry to touch. Rosemary easily becomes sodden if over-watered and can survive in dry conditions. This means a good soak every ten days or so.
Prune rosemary by cutting not more than one-third of the plant and making cuts above the leaf joint. Pruning encourages a bushier appearance, and clippings can be propagated, or dried and used in the kitchen for cooking or for scenting linens in the linen cupboard if slipped between sheets and towels.
Repot potted rosemary periodically--the indication that roots are becoming root bound is a yellow discoloration on the leaves. Repotting should be undertaken at least yearly.