Clematis

Clematis 'Jackmanii'

climberRanunculaceae

Clematis (Clematis 'Jackmanii') is a climber from the Ranunculaceae family that grows up to 500cm tall. This plant thrives in full sun to partial shade and requires moderate maintenance. Blooms in early summer and summer and late summer with purple, blue, pink, white, red flowers and attracts bees and butterflies.

Hoogte

200–500 cm

Breedte

100–200 cm

Zonligging

full sun, partial shade

Waterbehoefte

moderate

Grondsoort

loam, chalky soil

Onderhoud

moderate maintenance

Bloeitijd

early summer, summer, late summer

Bloemkleuren

purple, blue, pink, white, red

Ecologische waarde

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Care tips

Planting

Clematis 'Jackmanii' thrives in full sun or partial shade, ideally with its roots in cool shade and its head in the sun. Choose a position against a wall, fence, trellis, or pergola where the plant can climb freely. This cultivar tolerates both loam and chalky soils, but the ground must be well-drained yet moisture-retentive. Before planting, dig a hole roughly 45 cm wide and deep, and work in plenty of organic matter such as well-rotted compost or manure to improve soil structure and fertility. Plant between March and May or in September and October. Set the rootball about 8–10 cm deeper than it sat in its pot; this encourages new shoots to develop from below ground and helps the plant recover if clematis wilt strikes. Space plants 200 cm apart if you're planting more than one. Spread the roots gently in the planting hole, backfill with improved soil, and firm in carefully. Water thoroughly immediately after planting to settle the soil around the roots. Apply a 5–8 cm layer of mulch such as compost, bark chips, or gravel around the base, keeping it a few centimetres clear of the stems to prevent rot. This mulch keeps the roots cool and conserves moisture. Install support at planting time—clematis 'Jackmanii' climbs by twining leaf stalks, so provide canes, wires, or trellis with gaps of 10–15 cm. Tie in the main stems loosely with soft twine to guide initial growth, and water regularly during the first growing season until the plant is established.

Pruning

Clematis 'Jackmanii' belongs to pruning group 3 (also called group C or the late-flowering group), which means it flowers on the current season's growth and benefits from hard pruning each year. Prune in February or March, before new growth begins in earnest. This timing encourages vigorous shoots that will carry flowers from early summer through to late summer. Use clean, sharp secateurs or loppers. Cut all stems back hard to a pair of strong buds roughly 20–30 cm above ground level. Don't be timid—this cultivar responds well to severe pruning and will quickly produce plenty of new growth once the weather warms. If you leave old stems unpruned, the plant becomes a tangled mass of bare, woody growth at the base with flowers appearing only at the top, well out of sight. As you prune, remove any dead, damaged, or weak stems entirely. Disentangle the old growth carefully from its support; clematis stems can be brittle, so work patiently. After pruning, the plant will look like a collection of short stubs, but by late spring it will have produced a framework of fresh shoots. Tie these in loosely as they grow to spread them evenly across the support and maximise flowering coverage. If your clematis has become severely overgrown or neglected, the same hard pruning in late winter will rejuvenate it. You may sacrifice one season's flowers, but the plant will reward you with healthier, more abundant blooms the following year.

Maintenance

Water clematis 'Jackmanii' regularly during the growing season, especially in dry spells. The roots need consistent moisture but must never sit in waterlogged soil. In spring and summer, water deeply once or twice a week if rainfall is scarce; in autumn and winter, natural rainfall is usually sufficient. Mulch helps retain moisture and keeps roots cool, so top up the layer each spring if it has thinned. Feed in March or early April with a general-purpose balanced fertiliser such as blood, fish, and bone or a slow-release granular feed, scattering it around the base and watering in well. Apply a second feed in June, ideally using a potassium-rich fertiliser such as tomato feed to encourage flowering. Avoid high-nitrogen feeds after spring, as these promote leafy growth at the expense of blooms. Clematis 'Jackmanii' is fully hardy in zones 4a–9b and needs no special winter protection in temperate Europe. The hard pruning in late winter naturally removes any frost-damaged growth. However, young plants benefit from a thicker mulch layer in their first winter. Watch for clematis wilt, a fungal disease that causes shoots to collapse suddenly, usually in late spring or early summer. If it strikes, cut affected stems back to healthy tissue below ground level; new shoots often emerge from the base thanks to the deep planting. Aphids, earwigs, and slugs can damage young growth—check regularly in spring and remove pests by hand or treat with an appropriate organic control. Powdery mildew may appear on leaves in dry summers; improve air circulation and water the roots, not the foliage.