Bountiful Gardens

Thunbergia: The Cheerful Black-Eyed Susan Vine

Thunbergia, most commonly known by the species Thunbergia alata or the Black-Eyed Susan Vine, is a delightful and fast-growing flowering vine. It is cherished for its charming, simple flowers that pop against a backdrop of heart-shaped green leaves. While the classic variety features bright yellow or sunny orange petals with a distinct, deep-purple to black center that looks like an "eye," modern cultivars have expanded the palette to include shades of white, salmon, and apricot. Grown as an annual in our climate, this vine brings a cheerful, vertical element to the garden with remarkable speed.  This vine is wonderfully easy to grow, asking only for a bit of support to show off its climbing habit.

Why is Thunbergia So Popular?

The Black-Eyed Susan Vine is a staple in many gardens for its combination of beauty and vigor. Its popularity stems from several key attributes:

Rapid Growth: It is an incredibly fast grower, able to quickly scramble up a trellis, cover a mailbox post, or spill energetically from a hanging basket in a single season.

Cheerful Blooms: The bright, happy-looking flowers bloom profusely from summer until the first frost, providing a long season of color.

Versatility: It is equally beautiful whether trained to climb a support or allowed to trail and cascade from containers, window boxes, and hanging baskets.

Easy for Beginners: It's a very forgiving plant that delivers impressive results with minimal fuss, making it perfect for new gardeners.

Attracts Pollinators: The open-faced flowers are a welcome sight for bees and butterflies.

When to Plant:

The best time to plant Thunbergia is in the spring or summer, well after the last frost has passed and the soil has become thoroughly warm.

Growing Instructions:

Sunlight: Plant in full sun for the most prolific blooming. It can tolerate some light afternoon shade, but flowering will be best with at least 6 hours of direct sun.

Support: This is essential. Thunbergia is a twining vine and needs something to climb. Provide a trellis, arbor, fence, or even simple netting or strings for it to grasp. If planting in a hanging basket, no support is needed as it will happily cascade over the sides.

Soil: It is not picky about soil but performs best in standard, well-draining potting mix or garden soil.

Watering: It prefers consistent moisture to fuel its rapid growth. Water regularly, especially for plants in containers during hot, dry weather, but avoid letting the soil become waterlogged.

Fertilizing: To keep it blooming vigorously, feed container-grown plants with a balanced, water-soluble fertilizer every 2-3 weeks. In-ground plants in reasonably fertile soil require less frequent feeding.

A History from Africa to the World's Gardens

The genus Thunbergia is native to tropical regions of Africa, Madagascar, and Southern Asia. It was named in honor of Carl Peter Thunberg (1743-1828), a highly accomplished Swedish naturalist and a student of the legendary botanist Carl Linnaeus.

Thunberg was an intrepid explorer and scientist, often called the "father of South African botany" for his extensive work documenting the flora of the region. He also undertook a perilous journey to Japan, which was largely closed to foreigners at the time, where he collected and described hundreds of new plant species. Naming this beautiful African vine after him was a fitting tribute to his immense contributions to the world of botany.