Images Depict Mature Plants
Black Truffle Lobelia
Lobelia cardinalis 'Black Truffle'
Black Truffle Lobelia is the cardinal flower I’d use when the foliage needs to work as hard as the flowers. The dark leaves are beautiful long before bloom time, and the red flower spikes are a hummingbird magnet. Give it moisture, sun to part shade, and a spot where the contrast can show. It is especially good near pond edges, in rain gardens, and mixed with other moisture-loving native perennials.
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A Dark-Foliage Cardinal Flower with Brilliant Red Blooms
Dark Chocolate Foliage with High-Impact Contrast
Black Truffle Lobelia is a dramatic cardinal flower cultivar grown for its dark chocolate-purple foliage and brilliant red flower spikes. Also called Black Truffle Cardinal Flower, this upright perennial brings bold contrast to moist borders, rain gardens, pond edges, and pollinator beds.
The foliage emerges especially dark in spring, often appearing shiny and nearly black before warming to rich maroon and dark purple tones during the growing season. This foliage color gives Black Truffle more season-long interest than many green-leaved cardinal flowers, even before the flowers open.
Scarlet-Red Flower Spikes for Hummingbirds
From midsummer into fall, Black Truffle Lobelia produces upright spikes of deep red tubular flowers. These blooms add strong vertical color and pair beautifully with the dark foliage below.
The red flowers are especially valuable for hummingbirds, making this plant a standout choice for hummingbird gardens, pollinator plantings, rain gardens, and moist native-style beds. Butterflies and other pollinators may also visit the flowers, adding ecological value to the showy display.
Perfect for Rain Gardens, Pond Edges, and Moist Borders
Black Truffle Lobelia performs best where the soil stays consistently moist. Use it in rain gardens, low spots, pond edges, streamside beds, moist meadows, and along reliable water borders. It can also grow in average garden soil if watering is consistent, especially during establishment and hot weather.
This is not a dry-soil perennial. For best performance, avoid sites that dry out for long periods. In full sun, steady moisture is especially important. In warmer climates, part shade can help protect foliage and reduce stress during summer heat.
Upright Structure with Native Cardinal Flower Heritage
Black Truffle typically grows about 3–4 feet tall and 2–3 feet wide, giving it enough presence to stand out in the garden without becoming woody or bulky. The upright flower spikes add height and drama to mixed perennial beds.
Because it is a selection of Lobelia cardinalis, Black Truffle carries the garden appeal of native cardinal flower with the added benefit of dark foliage. Use it with other moisture-loving perennials to create layered late-season color and a stronger habitat planting.
Low Maintenance with Moisture and Seasonal Cleanup
Plant Black Truffle Lobelia in full sun to part shade with moist to wet, well-drained soil. It appreciates organic matter and consistent moisture, especially during the first growing season and while flowering.
Cut back old stems in late winter or early spring, before new growth begins. Deadheading is optional, but leaving some spent flowers can support natural reseeding where conditions are favorable. Divide or thin clumps in spring if plants become crowded.
| Hardiness Zone: | 3-9 |
|---|---|
| Mature Height: | 3 to 4 Feet |
| Mature Width: | 2 to 3 Feet |
| Sunlight | Full sun to part shade; part shade is helpful in hotter or drier sites |
| Soil | Average to moist, fertile, well-drained soil; performs best with consistent moisture |
| Water | Water regularly after planting; prefers moist to wet soil and should not dry out for long periods |
| Bloom Time / Color | Midsummer to fall; bold red to scarlet-red tubular flower spikes |
| Ornamental Features | Dark foliage, red flower spikes, upright habit, hummingbird appeal, dramatic late-season contrast |
| Wildlife Value | Attracts hummingbirds, butterflies, bees, and other pollinators |
| Resistance | Generally deer resistant; low maintenance with consistent moisture |
| Landscape Uses | Rain garden, hummingbird garden, pollinator garden, pond edge, streamside planting, moist border, native-style garden, cut flower garden, mixed perennial bed |
How to Care for Black Truffle Lobelia
Before you purchase your Black Truffle Lobelia, be sure to read the care instructions to keep your plant happy and healthy for years to come!
How should I plant Black Truffle Lobelia?
Plant Black Truffle Lobelia in full sun to part shade with consistently moist, well-drained soil. Choose a location where the dark foliage and red flower spikes can be seen, such as a rain garden, pond edge, moist border, hummingbird garden, or pollinator planting. Dig a hole about as wide as the root ball and just as deep. Set the crown level with the surrounding soil, backfill gently, and water thoroughly. Space plants about 18–24 inches apart, or up to 2–3 feet apart if you want each clump to mature with more room.
How often should I water Black Truffle Lobelia after planting?
Water Black Truffle Lobelia deeply after planting, then keep the soil consistently moist while roots establish. During the first growing season, water when the top few inches of soil begin to dry. Established plants still perform best with steady moisture, especially in full sun or during hot weather. Black Truffle can handle moist to wet sites, but it should not be allowed to dry out for long periods.
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When should I fertilize Black Truffle Lobelia?
Black Truffle Lobelia usually needs little fertilizer when planted in fertile, organic soil. A light spring topdressing of compost is often enough to support healthy growth, dark foliage, and strong flowering. Avoid heavy high-nitrogen fertilizing, which can encourage soft growth. Consistent moisture, good soil organic matter, and the right light exposure are more important than frequent feeding.
When and how should I prune Black Truffle Lobelia?
Cut Black Truffle Lobelia back in late winter or early spring before new growth begins. Remove old stems and seed stalks to make room for fresh spring growth from the crown. Deadheading is optional. Remove spent flower spikes for a tidier look, or leave some seed heads if you want to encourage natural reseeding in a rain garden or native-style planting.
