Lobelia, named after the Flemish botanist Matthias de Lobel is a diverse genus of flowering plants with over 400 species, admired for their vibrant flowers and versatility in gardens. While most Lobelia species prefer warmer climates, some can tolerate colder conditions. This guide provides a comprehensive overview of Lobelia, covering its characteristics, native habitat, landscaping uses, planting and care instructions, and other essential insights for gardeners.

What Makes Lobelia Special? Lobelia stands out due to its unique and attractive flowers, which come in a wide array of colors, including blue, purple, red, white, and pink. The flowers are typically tubular and two-lipped, with five lobes. The upper two lobes may be erect, while the lower three lobes often fan out, creating a distinctive appearance. Lobelia's long flowering period, extending from spring to fall, provides continuous color and visual interest in the garden. Many species are also excellent for attracting pollinators such as bees, butterflies, and hummingbirds.

Lobelia's adaptability to different environments is truly remarkable. From the "tree lobelias" found in the mountains of tropical Africa to moisture-loving species like Great Blue Lobelia that thrive in wetlands , this genus showcases its versatility and potential for diverse garden settings.

Description and Details Lobelias are primarily herbaceous plants, with some being shrubby and even exhibiting unique tree-like forms in certain environments. They display a variety of growth habits, ranging from compact and trailing to upright and bushy. The leaves are typically simple and alternately arranged along the stems, with shapes varying from lance-shaped to oval. The flowers are often borne in racemes (elongated clusters with stalked flowers) or spikes.

Here are some of the most popular Lobelia species cultivated in gardens:

• Cardinal flower (Lobelia cardinalis): This perennial variety has tall, upright stems with vibrant red flowers. It prefers full sun to partial shade and moist soil.
• Blue lobelia (Lobelia siphilitica): This perennial Lobelia features blue flowers and prefers moist locations in full sun to part shade. It can grow up to 3 feet tall. The leaves of Great Blue Lobelia can be long and narrow with tapered ends (ovate or broadly elliptic) or may be more rounded at one or both ends (oblanceolate to obovate).
• Trailing lobelia (Lobelia erinus): This widely cultivated annual species is known for its profuse blooms and cascading growth habit, making it perfect for hanging baskets and containers. It comes in a wide variety of flower colors, including blue, purple, red, white, and pink. It typically grows 6-8 inches tall but can trail up to a meter in length. The fruit of Lobelia erinus is a 5–8 mm capsule containing numerous small seeds.

Other notable Lobelia varieties include:

• _Lobelia x speciosa_: These are large-flowered hybrids between Lobelia cardinalis and Lobelia siphilitica. They come in a wide range of colors from white, blue, and deep purple through to vibrant red.
• _Lobelia tupa_: This striking variety has bright red flowers and dark green foliage. It is a half-hardy perennial that typically grows 1-2 feet tall.
• _Lobelia laxiflora_ subsp. _angustifolia_: This variety features slender arching stems with narrow leaves and blue flowers. It is a low-growing perennial that reaches about 8 inches in height.

Lobelia and Medicine Historically, some Lobelia species have been used in traditional medicine. Lobelia inflata (Indian tobacco) was particularly popular for its purported medicinal properties. It was used as an "asthmador" in Appalachian folk medicine. However, it is crucial to note that Lobelia contains lobeline, a toxic alkaloid that can be dangerous if ingested. Therefore, internal use of Lobelia is not recommended without the guidance of a qualified practitioner.

Native Habitat Lobelia species are found in various regions worldwide, mainly in tropical and warm temperate zones. They have a subcosmopolitan distribution, primarily in tropical to warm temperate regions, with a few species extending into cooler temperate regions.

Great blue lobelia (Lobelia siphilitica) is native to North America and is typically found in damp to wet ground, often in areas with some shade. Its habitat includes roadside ditches, floodplains, lake margins, swamp forest, and wet prairies. It prefers moist to wet soil and can tolerate full sun if sufficient moisture is present. Lobelia siphilitica has a wetland indicator status of FACW (Facultative Wetland), meaning it is frequently found in wetlands but can also occur in non-wetlands. This makes it a suitable choice for gardeners interested in creating wetland or rain gardens.

Landscaping Design Tips Lobelia's versatility makes it suitable for various landscaping applications:

• Borders and Edging: Upright varieties like Lobelia cardinalis and Lobelia siphilitica are well-suited for borders or background plantings. Compact varieties like Lobelia erinus 'Crystal Palace' are excellent for edging pathways and borders.
• Containers and Hanging Baskets: Trailing varieties, often cultivars of Lobelia erinus, are ideal for hanging baskets, window boxes, and cascading over walls.
• Ground Cover: Some Lobelia species can be used as a weed-suppressing ground cover, especially in shady areas with moist soil.
• Pollinator Gardens: Lobelia's vibrant colors and nectar-rich flowers attract pollinators like bees, butterflies, and hummingbirds, making them a valuable addition to pollinator gardens.
• Water Gardens: Certain species, such as Lobelia cardinalis and Lobelia siphilitica, thrive in moist environments and can be incorporated into water gardens or planted near ponds and streams.

Lobelia is also an excellent choice for creating contrasting color schemes in the garden. For example, blue Lobelia can be paired with yellow, orange, or red flowers for a bold contrast, while violet-purple Lobelia complements gold, fuchsia, or red flowers beautifully.

Companion Plants Companion planting involves pairing plants that benefit each other in various ways, such as attracting beneficial insects, deterring pests, or providing support. Lobelia can be paired with various companion plants to create stunning combinations and enhance the overall health and beauty of your garden. When selecting companion plants for Lobelia, it is essential to consider their growing requirements, such as light, moisture, and soil preferences.

Planting and Care

Planting

• Timing: In most regions, it is best to plant Lobelia transplants in the spring after the danger of frost has passed. For hot summer climates, consider planting in late September through December for blooms in early spring.
• Location: Lobelia can tolerate a variety of light conditions but prefers full sun to partial shade. In hotter climates, it is best to provide some shade, especially during the afternoon. Consider planting Lobelia on the north side of your home to protect it from intense sunlight. Lobelia species are generally hardy, with hardiness ratings ranging from RHS H3-H5.
• Soil: Lobelia prefers well-draining, moist soil that is rich in organic matter. Amend the planting area with compost or a good quality potting mix before planting.
• Spacing: Space Lobelia plants 6-18 inches apart, depending on the variety.

Care

• Watering: Lobelia prefers consistently moist soil, so water regularly, especially during hot weather or dry spells. Avoid overwatering, which can lead to root rot.
• Mulching: Apply a layer of mulch around the base of the plant to retain moisture, suppress weeds, and regulate soil temperature.
• Fertilizing: Lobelia benefits from regular fertilization throughout the growing season. You can use a time-release fertilizer at planting and supplement with a liquid fertilizer every 4-6 weeks.
• Deadheading: If plants become leggy or flowers begin to wane, lightly shear plants by up to a third and fertilize to encourage new branching and flowering.
• Pinching: In early spring, pinch back newly emerging stems that are about six inches long to encourage a more compact plant.

Temperature Lobelia prefers winter temperatures in the range of 40°F to 80°F.

Propagating Lobelia Lobelia can be propagated from seeds or stem cuttings.

Propagating from Seeds:

• Start seeds indoors 8 to 10 weeks before the last frost.
• Use a high-quality seed compost and water thoroughly.
• Sprinkle seeds on the surface of the soil but do not cover them.
• Keep the soil moist and maintain a temperature between 65°F and 75°F.

Propagating from Stem Cuttings:

• Spring is the ideal time for taking stem cuttings.
• Choose healthy stems and cut them to about 4-6 inches long.
• Remove the lower leaves and dip the cut end in rooting hormone (optional).
• Plant the cuttings in a moist potting mix and keep them in a warm, humid environment.

Other Insights for Gardeners

• Pollinator Attraction: Lobelia is a magnet for pollinators, especially bees and hummingbirds. The tubular shape of the flowers and the abundance of nectar make them particularly appealing to these beneficial creatures. Interestingly, the weight of a bumblebee plays a crucial role in pollination. When a bumblebee lands on the lower petals of a Lobelia flower, its weight depresses the petals, allowing the bee to access the nectar and pollen within.
• Toxicity: All parts of the Lobelia plant are toxic if ingested and can cause serious health problems. Keep children and pets away from these plants.
• Pests and Diseases: Lobelia is generally resistant to pests and diseases, but it can be susceptible to fungal diseases and stem rot if overwatered. Ensure proper drainage and avoid excessive moisture to prevent these issues.

Lobelia is a captivating genus that offers a wide variety of choices for gardeners. With its vibrant flowers, diverse growth habits, and long blooming period, Lobelia can add beauty and interest to any garden. By understanding its specific needs and characteristics, gardeners can successfully cultivate these stunning plants and enjoy their captivating blooms for months to come. Whether you are looking to create a vibrant border, a cascading hanging basket, or a pollinator-friendly haven, Lobelia's unique beauty and ease of care make it a rewarding addition to any garden.