Black and Blue salvia (Salvia guaranitica "Black and Blue") is an anise-scented sage cultivar which may grow up to 6 feet tall in ideal growing conditions, producing 15-inch spikes of deep blue, two-lipped flowers from mid-summer into fall. Effective as a border, bedding or container plant, Black and Blue salvia offers the added benefit of attracting hummingbirds and butterflies to the garden. The low-maintenance perennial requires little care to thrive.
This plant likes regular watering, preferably once or twice a week, especially during the summers. However, make sure to drain the soil completely. Whenever the top 2″ inches of the soil is dry, water it. The plants love a humid atmosphere and grow well in around 50% humidity.
Anise-scented sage requires full sun to partial shade to grow well. However, keep it under a sheltered, well-lit spot, preferably south-facing or west-facing. Avoid a north facing planting if possible.
Only the container-grown plants require monthly fertilizer. In a garden, they require little fertilizer as an excess of it can reduce flower production.
They love rich, well-drained soil. Avoid poorly-drained soils as that can cause root rot. Go for sandy, chalky, and loamy soils with a slightly acidic pH of 5.5 – 6.5.
Black and blue sage is simple to prune. Once it’s through flowering, simply cut off the stems all the way to the ground. Prune once or twice a year after the flowers have died or faded.