Clematis

Clematis (Clematis hybrids)

Large-flowered Clematis, Hybrid Clematis

Full to part sun, medium moisture, well-drained soil essential — roots rot in standing water; tolerates clay only when amended with organic matter; pH 6.0–7.0; classic guideline: "head in the sun, feet in the shade."

6–20 feet tall depending on cultivar, blooming spring through fall depending on pruning group; flowers 4–8 inches across in white, pink, red, purple, or bicolor; climbs by petiole wrapping, requires a trellis or support no thicker than 1/2 inch in diameter.

Propagation by internodal stem cuttings in late spring; pruning group (1, 2, or 3) determines timing and method — incorrect pruning is the most common cause of non-flowering.

Native region: Not native to Tennessee; ornamental introductions from Europe and Asia, widely hybridized since the 19th century.

Clematis hybrids are among the most purchased flowering vines in Middle Tennessee garden centers, yet failure rates are high. The most common problems in Columbia-area gardens are: (1) clematis wilt (Calophoma clematidina), a fungal pathogen that collapses new shoots rapidly — cut infected stems to ground level and the plant typically recovers from undamaged crown buds; (2) root rot from planting too deep or in poorly drained clay soil — set the crown 2–3 inches below soil surface and amend clay with compost; (3) spider mite infestations during Middle Tennessee's dry spells in July–August. The Zone 6b/7a transition zone suits most group 2 and group 3 hybrids well. Mulch the root zone heavily to moderate the soil temperature swings between winter cold and summer heat.