How to Grow Canna Lily 'Black Knight'
Wikimedia Commons
Canna Lily 'Black Knight'
Canna × generalis 'Black Knight'
flowerCanna 'Black Knight' is a striking tropical perennial featuring deep burgundy-black foliage with vibrant red flowers that bloom in tall spikes throughout summer and fall. This bold cultivar reaches 4-5 feet tall and makes an excellent focal point in gardens, containers, and tropical landscapes. It brings dramatic color and architectural interest to any planting scheme.
When should you plant Canna Lily 'Black Knight' in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Canna Lily 'Black Knight' timeline · Pittsburgh, PA (Zone 6b)
-
Plant Canna Lily 'Black Knight'
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
First Canna Lily 'Black Knight' blooms
Around Jul 16≈ 90 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Canna Lily 'Black Knight' dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 7b-11, where it can overwinter outdoors; grown as an annual or potted plant in colder zones
Sign up free to see if Canna Lily 'Black Knight' grows in your zone — and get a personalized planting timeline.
Get my Canna Lily 'Black Knight' timeline →Growth Stages
Dormancy/Planting
2-4 weeksRhizomes are dormant and just planted in soil or stored in cool conditions
Plant rhizomes in spring after last frost. Soak rhizomes overnight before planting to encourage sprouting. Keep soil warm (70°F+) to trigger growth.
Sprouting & Vegetative Growth
4-6 weeksShoots emerge from rhizomes; dark burgundy stems and foliage develop rapidly
Maintain consistent moisture and warmth. Feed with balanced fertilizer every 2-3 weeks. Remove any weak shoots to encourage strong growth.
Stem Elongation
3-4 weeksTall stems with large, deep burgundy leaves grow upward; plant reaches mature height
Support tall stems if in windy locations. Continue regular feeding with balanced or slightly higher potassium fertilizer. Keep soil consistently moist.
Flowering
8-12 weeks (summer through fall)Tall spikes of bright red flowers emerge from the foliage, creating dramatic color contrast against dark leaves
Deadhead spent flower spikes to encourage continuous blooming. Maintain consistent watering and weekly fertilizing with higher phosphorus to support flowering.
Senescence & Dormancy
4-6 weeksIn fall and winter, foliage begins to yellow and die back in cooler zones; rhizomes prepare for dormancy
In zones 7b-8, mulch heavily (6-8 inches) to protect rhizomes. In colder zones, dig rhizomes after first frost, dry them, and store in cool (50-60°F), dry conditions over winter.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Spray with water to dislodge; use miticide if severe. Increase humidity to deter.
-
Remove affected leaves. Apply insecticidal soap or neem oil. Maintain good air circulation.
-
Hand-pick in early morning; use pheromone traps away from plants. Apply insecticide if population is severe.
-
Remove by hand or prune affected foliage. Apply Bacillus thuringiensis (Bt) if infestation is heavy.
-
and
Remove manually, especially at night. Use beer traps or copper barriers. Reduce mulch contact with soil.
Uses
Edible Rhizomes
CulinaryCanna rhizomes are edible and nutritious, with a starchy tuber similar to taro that can be boiled, roasted, or ground into flour. In tropical regions, they are cultivated for food and have been used for centuries by indigenous peoples. [source]
Bold Focal Point & Landscaping
OrnamentalThe striking dark burgundy foliage and bright red flowers make 'Black Knight' an excellent choice for creating dramatic focal points, tropical gardens, water features, and containers. The tall, architectural form provides vertical interest and defines garden spaces. [source]
Pollinator Attraction
WildlifeCanna flowers attract hummingbirds, bees, and butterflies, making them valuable for pollinator gardens and increasing biodiversity in landscapes. [source]
Cut Flower Arrangements
HouseholdThe tall, colorful flower spikes and dramatic foliage make excellent long-lasting cut flowers for large arrangements and contemporary floral designs. [source]
Traditional Medicine Uses
MedicinalIn traditional and indigenous medicine, canna has been used to treat various ailments including inflammation, wounds, and digestive issues, though scientific validation is limited. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Canna lilies are grown for ornamental flowers and foliage, not harvest. Deadhead spent flower spikes regularly to encourage more blooms throughout the season. Cut flowers last 1-2 weeks in arrangements. In fall before frost, dig rhizomes carefully, dry for 1-2 weeks, trim stems to 2 inches, and store in dry peat moss or sawdust at 50-60°F until spring.
Fun Facts
- 🌱 Canna 'Black Knight' is named for its deep, almost black foliage that resembles the dark armor of medieval knights, creating striking contrast with its bright red flowers.
- 🌱 Cannas are one of the few tropical plants that also grow well in temperate zones, making them exceptionally versatile for gardeners worldwide.
- 🌱 The plant was hybridized extensively in the 19th and early 20th centuries, and 'Black Knight' remains one of the most popular dark-foliaged varieties for its dramatic appearance and reliable performance.
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Canna Lily 'Black Knight' planting timeline
Tell us your zip code and we'll calculate exactly when to start Canna Lily 'Black Knight' seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Canna Lily 'Black Knight' timeline →