Black and blue salvias, also known by their botanical name Salvia guaranitica ‘Black and Blue’, are popular garden plants that can be grown as either annuals or perennials depending on your climate. Their striking cobalt blue flowers and dark calyces make them stand out in any garden. But should you plant them as annuals and replace them every year, or can you enjoy them as perennials that return each spring?
Annual vs Perennial
The difference between an annual and a perennial plant is their lifespan. Annuals complete their entire lifecycle in one growing season They germinate from seeds, grow, flower, set new seeds, and die all within a single year Perennials can live for many years, going dormant in winter then re-emerging the next spring.
Most plants are genetically programmed to be either annuals or perennials but there are some that fall in the middle. Black and blue salvias are one of these “tender perennials”. Their genetics make them capable of being long-lived perennials but they lack the cold hardiness to survive winters in some climates.
Native Climate
To understand how to best grow black and blue salvias, it helps to consider their native climate. This plant originated in Brazil, Paraguay, and northern Argentina where winters are mild. These parts of South America have a climate zone classification of 9 or warmer, meaning winter lows seldom drop below 20°F.
Black and blue salvias thrive in their native subtropical climate. The tuberous roots store enough energy over the growing season to keep the plants alive through winter. Then as temperatures warm in spring, new foliage emerges from the established root system.
Growing as Perennials
In areas with similarly warm winters, like Zone 9 and warmer, black and blue salvias are easy to grow as perennials. Once established, they will come back bigger and better each year. These include places like southern California, southern Florida, south Texas, and the Gulf Coast.
Farther north where winters get colder than Zone 9, this plant has a harder time overwintering. However, you can improve their odds by providing protection. Plant them in a sheltered microclimate, like against a south-facing wall. Surround the roots with mulch for insulation. Cover the plant with a fabric row cover or bring it into a cold frame or unheated greenhouse over winter.
With good siting and a bit of winter protection, you may be able to sucessfully overwinter black and blue salvia even in Zone 7 or possibly Zone 6. It’s worth trying if you are an avid gardener up for the challenge! Just be prepared that the plants may not make it through the winter some years despite your best efforts.
Growing as Annuals
In climates with cold winters, most gardeners choose to treat black and blue salvias as annuals. This means allowing the plants to die off when cold weather arrives then purchasing new plants each spring. Although more work, this guarantees you’ll have vigorous, flowering plants each growing season.
When grown as annuals, black and blue salvias are smaller, reaching just 2 to 3 feet tall during one season of growth. But they still bloom prolifically, producing their signature blue flower spikes for months on end. As a fast-growing annual, this salvia adds instant color and height to gardens or containers.
The main advantage to growing black and blue salvias as annuals is reliability. You start fresh with new plants each year rather than hoping older ones make it through winter. Annuals also tend to look better, lacking the leggy or woody growth that can plague perennials after some years.
Best Uses
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Containers – Since their lifespan is limited as annuals, black and blue salvias are a great choice for container plantings. They add vibrant color and attract hummingbirds and butterflies all season long.
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Borders and beds – The tall vertical shape stands out along borders, walkways, and as a backdrop to shorter flowers. Plant en masse for bold drifts of blue.
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Pollinator gardens – Butterflies, hummingbirds, and bees flock to the flower spikes. The nectar-filled blooms provide food for pollinators from midsummer into fall.
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Cottage gardens – The informal, naturalistic style of cottage gardens suits these tender perennials. Their spiky blue blossoms blend well with old-fashioned annuals and perennials.
Growing Tips
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Provide full sun exposure. At least 6 hours of direct sun per day is best. With too much shade, plants become leggy and flower less.
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Grow in rich, well-drained soil. Amend clay or sand with compost to create an ideal loamy soil.
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Establish new plants, then allow the soil to dry slightly between waterings. Avoid overwatering.
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Remove spent flower spikes to encourage continuous new blooms. Deadheading improves their appearance.
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Cut plants back to the ground in late winter, before new spring growth begins.
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Propagate by taking stem cuttings or dividing root clumps in spring.
Final Thoughts
The beauty of black and blue salvias lies in their vivid flower colors that energize the garden from midsummer into fall. Their adaptability as annuals or tender perennials lets you enjoy their benefits even in climates where they struggle to overwinter. With the right growing conditions, they will thrive and provide seasons of magical blue blossoms and plenty of pollinator activity.
Salvia ‘Black and Blue’ Plant Profile
FAQ
How do you winterize black and blue salvias?
Do salvias like sun or shade?
How to plant black and blue salvias in pots?
Is black and blue salvia a perennial?
‘Black and Blue’ salvia is an attractive cultivar that is grown as a perennial or subshrub. It is hardy in zones 7 through10, but it may be grown as an annual in colder climates. They are one of the most popular and common salvias on the market. This plant grows 2 to 5 feet tall and equally as wide. It has an upright, open, and clumping habit.
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.
What does black and blue salvia look like?
When ‘Black and Blue’ salvia is grown as an annual, it is shorter. It may only reach a height of 2.5 to 3 feet. The leaves of this plant appear wrinkled, and the undersides are a paler green than the upper surface. The deep cobalt blue flowers with the black calyx are distinctive for this cultivar.
What is Salvia guaranitica black and blue?
Salvia guaranitica black and blue is a species within the Salvia genus and belongs to the Lamiaceae family. This plant can be biennial, annual, evergreen, or herbaceous. It is known for its simple or pinnately-lobed, fragrant pale to dark green leaves and two-lipped blue flowers on spikes.
Why is Salvia a black & blue plant?
The genus name Salvia comes from the Latin word salveo meaning “to save or heal”, in reference to the purported medically curative properties attributed to some plants in the genus. ‘Black and Blue’ is a cultivar that features deep cobalt blue flowers with black calyces. Flowers appear on spikes to 15” long over a long mid-summer to fall bloom.
Is Salvia a perennial?
Varieties that grow in the southern zones – 7-10 – are considered perennials. Even though they are often grown as annuals in zones 3-6, it is possible for plants in zones 4-6 to come back the following year but as a new plant from the reseeding salvias in the fall. Though it often regrows, it is a different plant, not the same root.