The crimson plant (Salvia splendens) is also known as scarlet sage and red salvia. A native of Brazil and South America, the crimson plant is a perennial herb grown year-round in the warmer USDA planting zones, 9 and 10, and as a tender annual in all other zones where temperatures consistently fall below freezing during the winter. The bright red, tubular flowers bloom in late spring through September, against a back drop of dark, glossy green foliage, which can grow up to 3 feet tall. Whether growing as a border plant in the garden or in containers to decorate a patio, caring for crimson plants is easy enough for even the most novice gardener.
Grow perennial crimson plants in a location that receives full sun all day and in well-draining soil. If necessary, amend the soil with compost in early spring to help it drain better.
Water the plants deeply using a soaker hose so the foliage stays dry. Let the plants dry out down to 3 inches deep before watering again.
Apply an all-purpose, balanced fertilizer such as, 10-10-10, in early spring. Sprinkle about 1 tbsp. of a slow-release, granular fertilizer around each plant and water in well. These light feeders only need one application of fertilizer per growing season.
Apply a 2- to 3-inch layer of mulch around each plant in early spring. Use chopped leaves, dried grass clippings or wood chips. Mulch helps the soil maintain consistent moisture, discourages weeds and keeps the shallow roots cool, while also adding nutritional qualities to the soil as it breaks down.
Remove faded flowers right away to encourage new growth and keep the plant looking tidy. Either pinch or clip off the flowers at the point where the foliage begins.
Stake tall crimson plants, if needed, to protect them from winds and heavy rains. Use a 1- to 2-foot wooden stake and tie the plant to it with strips of nylon material or twine.