Jackman's Clematis Plant Profile

Never Again Fear Pruning This Popular Vine

Jackman clematis flower closeup.

Dragan Todorovic/Getty Images

Jackman's clematis is so commonly grown that some gardeners despise it for its very popularity. But that's a shame. Popular plants generally gain their popularity for good reasons. Jackman's clematis is a vigorous yet compact vine with fabulous flowers. The fact that a great many people grow it does not detract from these superior qualities; on the contrary, it confirms them.

  • Botanical Name: Clematis Jackmanii. The latter is the cultivar name and refers to 19th-century British nurseryman, George Jackman.
  • Common Name: Jackman's clematis, Jackman clematis, Jackman virgin's bower
  • Plant TypeDeciduouswoody, flowering vine
  • Mature Size: 10 to 13 feet (occasionally more)
  • Sun ExposureFull sun to partial shade
  • Soil Type: Fertile, well-drained, and kept evenly moist
  • Soil pH: Neutral
  • Bloom Time: July (zone 5)
  • Flower Color: Dark purple-violet
  • Hardiness Zones: 4 to 8
  • Native Area: The genus is indigenous to several regions across both the Northern Hemisphere and Southern Hemisphere.

How to Grow Jackman's Clematis

This vine is fussier about exactly how you plant it than many plants are. After you bring the vine home from the garden center and gently knock it out of its pot, plant it so that the top of the root ball lies 3 to 4 inches beneath ground level. Going down that deep promotes the development of what are termed "latent" buds below ground level. Their presence is your insurance policy against the disease, clematis wilt, which could cause above-ground vegetation on your vine to die.

The practice of deep planting also helps keep the roots cool. It is critical to shelter clematis roots from the blazing sun. Another way to keep your vine's roots cool is to spread about 2 inches of mulch over the root zone. Other gardeners shade the base of the vine with ground covers (but avoid any with deep root systems, as these would interfere with the root system of the clematis).

Still others place flagstones or other objects at the base to cast shade. However, the latter practice could provide an open invitation to a known clematis pest: Slugs like to eat clematis almost as much as Hosta. If you do go with flagstone, check it frequently and see if you can catch any slugs napping (rendering the flagstone essentially a "slug trap"). Dispatch any slugs that you do find. Pest damage can also come from earwigs and spider mites.

This perennial is considered a climber. It will twine its way around the support (trellis, etc.) that you provide for it.

Light

Treat this flowering vine as a perennial vine for sun in the North. But it can take a bit more shade than can many other types of clematis, and, in the South, it is a good idea to give it partial shade.

Soil

More so than with many other plants, a major soil consideration in growing Jackman's clematis is that the soil must be kept relatively cool. If the soil gets too hot, it is bad for this vine's roots.

Water

Do not let the soil dry out completely at any point during the period of active growth for the plant.

Fertilizer

If you are an organic gardener, fertilize with compost. Otherwise, apply a complete fertilizer each spring. Err on the side of too little when using commercial fertilizers rather than too much.

Best Features of Jackman's Clematis

Jackman's clematis is a hybrid plant, which is why the botanical name of this buttercup-family member is sometimes given as C. x Jackmanii, the parents being C. lanuginosa and C. viticella. Its large (5 inches across) blooms, which are deliciously dark, make it one of the prettiest flowering vines. This vine is big enough to capture your attention when in bloom without being too overpowering for a small space (as a taller type of clematis might be).

When to Prune Jackman's Clematis

Jackman's clematis falls into pruning class 3 (some prefer to say "pruning-type 3" or "pruning group 3"). That means:

  • It blooms on new wood.
  • And therefore the time to prune it is from late winter to early spring.

Some experts say it is best not to prune a new vine very much (unless it is to remove dead branches, which can be done at any time), advising you to give it time to put on some growth. But, once it matures, you may see it losing vigor (or it may just be getting too overgrown for your tastes), and that is the time to begin a spring pruning regimen (if you have not already). While some perform a drastic pruning, many growers prune clematis in a more targeted fashion, cutting the vines down to a preferred height where there are good leaf buds present.

Uses in Landscaping

A standard way in which to use the vine is as camouflage for eyesores in the landscape, or for landscaping around mailboxes, where the vine is trained up a mailbox post as a decoration. In fact, this latter use is so widespread that Allan Armitage jokingly lists "Clematis mailboxensis" in his catalog of perennials as if it were a variety that you could grow.

A wide variety of structures can serve as support for the vine's vertical growth, though, whether they be existing features in your landscape or features that you create specifically to showcase your clematis. Many growers train their clematis vines to climb upon other plants (shrubs and vines, mainly). Two famous garden writers, Armitage and Michael Dirr, make mention of this practice in their gardens. Just remember to clean up in fall by cutting back this growth, which will allow you to "hit the reset button" for next year.​

Other Dark-Flowered Types

Jackman's clematis is not the only kind with bluish or purple flowers. Others include:

  • C. Etoile Violette
  • C. Durandii
  • C. The President
  • C. macropetala Maidwell Hall
  • C. Venosa Violacea