Clematis ‘Jackmanii’ is one of the most famous and widely grown clematis varieties, introduced by the Jackman nursery in England. It was bred by George Jackman in 1858 and first exhibited in 1863. This variety came from a cross between Clematis lanuginosa and Clematis viticella or possibly Clematis hendersonii. Its introduction marked the beginning of the modern era of clematis cultivation, where large-flowered hybrids became popular.
Characteristics
- Flowers: ‘Jackmanii’ is renowned for its deep purple, velvety flowers. The blooms are large, typically 4 to 7 inches in diameter, with four to six sepals (often referred to as petals). The center of each flower features a contrasting light green or cream-colored stamen, which adds to its visual appeal.
- Growth Habit: This clematis is a vigorous climber, reaching heights of 8 to 12 feet or even more under ideal conditions. It uses its leaf petioles to cling onto supports like trellises, wires, or other plants.
- Pruning Group: ‘Jackmanii’ belongs to Pruning Group 3 (also known as Group C). This means it blooms on new wood, and for best flowering, it should be pruned hard in late winter or early spring, cutting back to a pair of strong buds about 12 inches from the ground.
- Bloom Time: It flowers from mid-summer to early fall, providing a long period of color.
- Foliage: The leaves are green, usually trifoliate, providing a lush backdrop to the vibrant flowers.
Cultivation
- Sunlight: Prefers full sun to partial shade. However, like many clematis, it’s best to keep its roots in shade while the upper part receives sunlight.
- Soil: Thrives in well-drained, fertile soil with a neutral to slightly alkaline pH. Mulching around the base can help keep the roots cool and moist.
- Watering: Consistent moisture is key, especially in the growing season, but the soil shouldn’t be waterlogged.
- Support: Needs a structure to climb on. This can be a trellis, arbor, or even other plants.
- Planting: When planting, it’s advisable to plant the clematis deeper than it was in the pot by about 2-3 inches. This helps in encouraging more shoots to come from below the soil, leading to a bushier plant.
- Fertilization: Benefits from regular feeding. A balanced fertilizer in spring followed by a bloom booster fertilizer after the first flush of flowers can enhance flowering.
- Disease and Pests: Clematis wilt can be a problem, though ‘Jackmanii’ is somewhat less prone than other large-flowered hybrids. Good air circulation and proper planting depth can minimize risks.
- Winter Care: In colder climates, provide some protection or mulch heavily around the base after cutting back in late winter.