Black and Blue Salvia (Salvia guaranitica ‘Black and Blue’) is a captivating perennial known for its deep blue, tubular flowers and contrasting dark calyces and stems. Blooming from late spring through fall, its rich nectar attracts hummingbirds, bees, and butterflies. This low-maintenance plant is a favored garden addition.
Planting and Site Selection
Proper planting and site selection are crucial for Black and Blue Salvia. Plant in early spring after the last frost. These plants thrive in full sun (at least six hours daily) for abundant flowering. While partial shade is tolerated, especially in hotter climates, too much shade can cause leggy growth.
Well-draining soil is essential to prevent root rot. A moderately fertile, sandy or loamy soil enriched with organic matter like compost works best. Loosen the soil to about 12 inches deep and incorporate compost for nutrients and drainage. Space plants two to three feet apart for air circulation, deterring fungal diseases.
Essential Care Practices
Consistent care maintains the health and prolific blooming of Black and Blue Salvia throughout the growing season.
Watering
Proper watering is important, especially during establishment. Newly planted salvia needs deep watering two to three times weekly until roots develop. Once established, it is moderately drought-tolerant but performs best with consistent moisture. Allow the top few inches of soil to dry out between waterings, typically once per week for mature plants. Avoid overhead watering to reduce fungal infection risk.
Fertilizing
Black and Blue Salvia is not a heavy feeder and thrives with minimal fertilization. Apply a balanced, slow-release fertilizer in early spring as new growth emerges. During peak blooming, a phosphorus-rich fertilizer every four to six weeks encourages continuous flowering. Avoid excessive nitrogen, which promotes foliage growth over flowers.
Pruning
Regular pruning benefits plant health, maintains shape, and encourages continuous blooms. Deadheading spent flower spikes prompts new flowers instead of seed production. For shaping or rejuvenation, cut back significantly in late fall or early spring, typically to about three inches above the soil line. Summer pruning of leggy stems promotes a bushier habit.
Addressing Common Issues
While Black and Blue Salvia is generally resilient, gardeners may encounter problems affecting its appearance and performance. Understanding these issues allows for timely intervention.
Black and Blue Salvia is generally pest-free. However, under very dry conditions, it can become susceptible to aphids or spider mites. Regular foliage inspection helps early detection, allowing for treatment with appropriate organic pest control methods.
Diseases can occur, particularly in conditions favoring fungal growth. Common concerns include powdery mildew (white spots on leaves) and root rot (from overly wet soil). These issues link to poor air circulation or overwatering. Proper plant spacing and avoiding overhead irrigation significantly reduce fungal problems.
Leggy growth or lack of blooms often relate to environmental factors. Insufficient sunlight causes stems to stretch, resulting in a leggy appearance and reduced flowering. Overwatering or excessive high-nitrogen fertilization also contributes to leggy, less floriferous plants. Adjusting location for more sunlight or refining watering and fertilization practices can resolve these concerns.
Winter Care and Overwintering
Black and Blue Salvia’s winter hardiness depends on the local climate. It is a tender perennial, reliably hardy in USDA Zones 7-10, where it typically returns each year. In warmer zones, the plant may remain evergreen or die back to the ground, re-emerging in spring.
In colder regions (Zone 6 and below), it is often grown as an annual due to sensitivity to freezing temperatures. Overwintering is possible with protective measures. Apply a thick layer of mulch (four to six inches deep) around the plant’s base to insulate roots. For potted plants, bring them indoors to a cool, bright location above freezing, like an unheated garage or basement. Some gardeners also dig up the plant, including its rhizomes, and store them in a cool, dry place over winter, similar to cannas.