Plant taxonomy classifies red salvia plants as Salvia splendens. Despite an official common name of scarlet sage, many people refer to the plants simply as red salvia. They are members of the mint family and, while technically a perennial plant, red salvia is often grown as an annual in temperate zones. Although the scarlet variety is the best known, Salvia splendens comes in other colors including white, salmon, pink, purple, lavender, burgundy, and orange. Best planted in mid-spring once the soil has warmed to at least 70 degrees Fahrenheit, red salvia will grow quickly, eventually reaching heights of 18 to 30 inches at maturity. The dark-green, heart-shaped leaves emit a fragrance that mammalian pests dislike, making them both deer and rabbit resistant. To improve the look of your red salvia (and to encourage them to produce bountiful flowers), it’s important to deadhead faded blooms. You can do this by pinching off the flower spikes that have finished blooming—make sure to pinch down to the bottom of the stems.
Light
Red salvia can grow successfully in a spot that receives partial shade, but ultimately it will grow (and bloom) better the more hours of sun it receives. Strive to plant your salvia in a location that gets at least six to eight hours of bright sunlight per day.
Soil
Plant your red salvia in soil that is moist but well-draining. The plant prefers a loamy mixture that is rich in organic matter but doesn’t get boggy or retain too much water. If the soil in your landscape isn’t nutrient-dense, amend it with organic matter before planting. Mulching the top layer of the soil can also help a sandy mixture retain a bit more moisture, especially during the hotter summer months.
Water
Red salvia plants like consistently moist soil, but overwatering them can cause roots to rot. Generally, a watering schedule of every seven to ten days is sufficient, depending on rainfall amounts and hot daytime temperatures. Before watering, verify that the first inch or two of soil is dry. If soil is dry, water deeply to ensure water reaches the plant roots.
Temperature and Humidity
Red salvia plants are fairly temperature-sensitive and prefer to be grown in soil (and environmental) temperatures that are consistent. Most importantly, red salvia is not frost tolerant and should not be subjected to prolonged temperatures below 32 degrees Fahrenheit. Red salvia does not have any special humidity needs.
Fertilizer
For best results, fertilize red salvia plants with the same balanced fertilizer you use to fertilize your other annual flowering plants. Generally, red salvia plants are not heavy feeders and will do fine with just one springtime fertilization.
Other Salvia Varieties
Many cultivars of salvia sold at garden centers and online. While they all have the same care requirements, they will often vary in both color and height. Some of the most popular varieties include:
‘Alba’: a variety with white flower spikes that can grow to 24 inches tall’Ablazin™ Purple’ a variety that produces royal purple flower spikes and can reach 26 inches tall’Carabiniere’: a compact variety with red flower spikes that grows to 14 inches tall’Salsa Scarlet Bicolor’: a unique variety that features bicolored red and white flower spikes and reaches a height of just 6 to 12 inches tall
Common Pests/Diseases
Monitor red salvia for pests like slugs, snails, and whitefly, all of which might bother the plants. In fact, when shopping for plants at the garden center, carefully inspect the undersides of the leaves for whitefly to avoid bringing any home with you. Whiteflies are notorious greenhouse pests, and, occasionally, they will make the trip from the greenhouse to the garden center, undiscovered. If a plant is infected, remove the pests with a strong blast of water (from a garden hose). If that doesn’t work, treat the plant with a mild insecticidal soap or horticultural oil like neem oil. Keep in mind, your applications will need to be repeated until all signs of infection have ceased.
