Salvia is the name for the family of plants known as sage, an herb in the mint family that is known for aromatic leaves that are used in seasoning. When used in cooking, sage gives fatty meats a slight peppery flavor. The leaves are oval and silvery green, and grow on a woody stem. Although there are many species of sage, only a few are grown for their culinary uses. Other varieties of sage shrub are used in landscaping for their attractive leaf displays.
When grown as an herb, salvia will remain useful for a maximum of five years. After that point the quality of the sage plant drops off. According to the National Gardening Association, once the quality of the salvia drops off, it is best to start new plants from seeds or cuttings to replace the old plant. Although plants may be started easily from seed, the seedlings may not have the same leaf shape and color as the parent plant, particularly if the seeds are gathered from a hybrid species of salvia.
Sage can be started from seed indoors before the last frost of the year to get a head start on the growing season, or sown directly into the ground once the chance for frost has passed. Like many herbs, salvia does well in full sun and well drained soil. The seed should be sown soon after harvesting. The seeds do not store well, and may lose their viability quickly.
If grown from seed, sage is slow to establish. Because of this, it is important to nourish the seedlings as they become established. Once a sage shrub becomes established, it is extremely hearty and may live through very harsh conditions.
Because sage is native to the Mediterranean, it is not fussy about the type of soil that it is grown in. However, once seedlings have germinated, you should feed them a weak, all-purpose liquid fertilizer in order to aide in their growth. Since seedlings are delicate, you should only apply liquid fertilizer at half-strength. Dilute the plant in twice as much water as the package directions say before watering. Once your sage seedlings develop three or four true leaves, you can increase the strength of your fertilizer.
Like many shrubs, sage will thrive if a handful of bonemeal is worked into the soil twice yearly. Bonemeal is rich in phosphorous and is an excellent source of calcium. If you are growing sage in containers, use bonemeal more sparingly by sprinkling it on the soil surface. The reason for this is that sterile potting soil has few of the microbes in the soil that help plants to process bone meal.
Sage requires very little fertilizer. If you fertilize the plant frequently, the shrub will grow prolifically but the leaves will have very little taste.