How to Grow Stunning Black and Blue Salvia from Seeds

Black and blue salvia (Salvia guaranitica ‘Black and Blue’) is a show-stopping flower loved for its rich saturated colors and towering height. The flower spikes are a vivid iridescent blue while the bud sepals are a deep midnight black. Combined together, it creates a gorgeous two-tone effect.

This tropical-looking salvia makes a dramatic statement planted in borders or containers. Hummingbirds also can’t resist the nectar-rich blossoms. Black and blue salvia thrives in zones 7-10 blooming from summer well into fall frost.

Read on to learn everything about growing black and blue salvia from seed. With proper care, you’ll be rewarded with these elegantly tall, colorful blooms:

Black and Blue Salvia Seed Basics

  • Botanical Name: Salvia guaranitica ‘Black and Blue’
  • Type: Tender perennial, grown as an annual in colder zones
  • USDA Zones: 7-10
  • Mature Size: 4-6 feet tall x 3 feet wide
  • Exposure: Full sun
  • Soil: Moist, well-drained soil
  • Germinates: 10-15 days at 70°F
  • Optimal Soil Temperature for Germination: 70-75°F
  • Seed Viability: 1-3 years

When to Sow Black and Blue Salvia Seeds

Because it’s a long season, heat loving plant, black and blue salvia should be started indoors 8-10 weeks before your last expected spring frost.

For most zones, aim to start seeds in early spring, around February or March. Use seed starting mix and sow seeds 1⁄4 inch deep indoors beneath grow lights or in a sunny window.

Maintain a soil temperature of 70-75°F for best germination, which takes 10-15 days. Grow the seedlings on at 65-70°F until transplanting time arrives in late spring after danger of frost.

Harden off the plants for 7-10 days before transplanting into the garden after all risk of frost. Space plants 18-24 inches apart in full sun locations with fertile, well-drained soil.

How to Grow Black and Blue Salvia from Seeds

Follow these tips for successfully growing black and blue salvia from seed:

  • Use fresh seed – Salvias seeds only stay viable for 1-3 years, so use fresh seed each season for best germination.

  • Pre-chill seeds – For quicker germination, chill seeds in the refrigerator for 5 days before sowing.

  • Use seed starter mix – Sow seeds in sterile seed starting mix to prevent fungus and damping off disease.

  • Plantseeds 1⁄4 inch deep – Cover the tiny seeds lightly, keeping soil moist but not saturated.

  • Cover seeds – Cover newly sown seeds with plastic wrap or a humidity dome to maintain even moisture.

  • Bottom heat helps – A heat mat or grow lights further encourages rapid, uniform germination.

  • Grow on at 65-75°F – Once seedlings emerge, remove the humidity dome and grow on the young plants with plenty of light.

  • Harden off – Acclimate seedlings to outdoor conditions for 7-10 days before transplanting into the garden after frost.

How to Care for Black and Blue Salvia

To keep your black and blue salvia thriving once transplanted:

  • Plant in full sun (at least 6 hours direct sun per day).

  • Space plants 18-24 inches apart to allow for growth.

  • Water regularly to keep moist, especially in dry conditions.

  • Apply a balanced liquid fertilizer every 2-3 weeks during the growing season.

  • Stake tall stems as needed to prevent flopping.

  • Prune back by 1/3 after initial summer bloom to encourage re-blooming into fall.

  • Mulch plants to retain soil moisture and suppress weeds.

  • Lift tubers or take stem cuttings in fall to overwinter in zones 8 or below.

Common Problems and Solutions For Black and Blue Salvia

Leggy, weak seedlings – Insufficient light, overcrowding. Give more light, avoid overwatering.

Failure to bloom – Too much nitrogen fertilizer, overcrowding, or insufficient sunlight.

Leaf spot diseases – Improve air circulation and avoid wetting foliage. Remove diseased leaves promptly.

Inadequate flowering – Pinch back spent flowers to encourage reblooming. Needs full sun.

Flopping – Stake tall flower spikes that begin to bend over with supports.

** root rot** – Improve drainage and do not overwater. Allow soil to dry between waterings.

Tips for Using Black and Blue Salvia in Gardens

  • Highlight black and blue salvia in borders, beds, and container plantings

  • Allow plenty of space for the tall flower spikes and bushy foliage

  • Underplant with lower growing annuals and perennials

  • Use as a backdrop for smaller plants

  • Feature in pollinator and butterfly gardens

  • Cut flower spikes for striking arrangements

Alternate Salvia Varieties to Grow

If black and blue salvia isn’t hardy or suitable for your growing zone or conditions, consider planting these other impressive Salvias from seed:

  • Scarlet Sage – Vibrant red blooms on 18-30 inch plants. Hardy annual.

  • Autumn Sage – Long blooming with red, pink, or white flowers. Perennial in zones 9-11.

  • Mexican Bush Sage – Heat and drought tolerant with purple-blue flowers. Hardy perennial.

  • Pineapple Sage – Brilliant red blooms and sweet, fruity scent. Tender perennial for warmer zones.

Whatever Salvia variety you choose to grow from seed, you’ll be rewarded with season-long color on these beloved hummingbird magnets. With stunning black and blue blooms rising elegantly on tall, multi-branching stalks, this exotic-looking salvia makes an unforgettable statement in the garden.

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‘Black and Blue’ Salvia (Salvia guarunitica) Growing Information for Home Gardens

What is a black and blue salvia?

The description of these plants has been written based on numerous outside resources. One of the most popular salvias, Salvia guaranitica ‘Black and Blue’ (Anise-Scented Sage) is a particularly attractive perennial featuring showy spikes of large, deep cobalt blue flowers, 2 in. long (5 cm), emerging from black calyces.

How tall does black and blue salvia grow?

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.

Is Salvia guaranitica a perennial?

Salvia guaranitica black and blue is an attractive perennial that bears cobalt blue flowers and either light green or black calyces. Also known as “Black and Blue” Salvia, the cultivar belongs to the Salvia genus of evergreen shrubs. Native to southern South America, especially Brazil, the plant height is 6′ feet tall and is grown as an annual.

Can Salvia be grown from seed?

Salvia can be grown from seed, but ‘Black and Blue’ is best propagated from cuttings, and I’ve relied on starter plants, which thrive on the sunny front steps. (There are a few plants on the shady north side of the house, and these perform admirably, although some of the stems tend to overreach if they don’t receive a few hours of direct sun.)

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