Clematis Jackmanii (Jackman Clematis) Plant Care Guide & Tips

Last Updated on October 31, 2021 by Phil

The Clematis Jackmanii is a beautiful flowering vines that grows best when trained to climb on different structures in your yard, garden or porch. It is likewise called by a few other names including Jackmanii Clematis, Jackman clematis and Jackman’s clematis.

The plant is actually a hybrid that was borne from the Clematis viticella and Clematic lanuginose. And as you would guess, its beauty is the reason it is one o the most popular flowering vines around.

That plant is well known for its stunning large dark purple blooms which bloom around June and late summer). It ability to grow to between 8 to 12 feet upon maturity covering a spread of about 4 to 6 feet also makes it an eye catching specimen. As such, you do want to give it enough space to grown.

Table of Contents

Clematis Jackmanii Plant Care

Clematis Jackmanii Light

The clematis jackmanii likes full sun and partial shade depending on where you live and what location you put it in. To explain, its ideal scenario would get to get full sun but keep its roots in cool in shade. This makes it a little bit more tricky compared to other plant.

One way to do this is to add mulch to keep its roots protected during hot weather. You can likewise grown groundcover around them which will work as well. Either way, to grow at its best and flower optimally, this clematis variety will need at least 6 hours of light daily.

It also means that if situated facing north, the Jackman clematis will do best when provided with full sun, including that in the mid afternoon.

However, if placed facing the south, it’s best position will be under partial shade while still receiving lots of bright light. This is especially true under the hot afternoon sun.

Clematis Jackmanii Temperature & Humidity

This flowering vine likes fairly warm conditions. As such, you want to keep temperature above 60 degrees Fahrenheit. And, it will begin to struggle once the climate drops below 55 degrees.

As such, it does best in USDA zones 4 to 8. Midwest and Northeast. The combination of weather and sunlight makes this plant prevalent in the Pacific Northwest, Southeast

However, in the colder regions, you do need to protect it from frost. Using a thick layer of much works very well. For larger plants, you may need to use other kinds of covering like tents, tarps or blankets.

Without ample protection, the winter cold will kill the plant all the way down. By protecting it, you’ll see it bounce right back come springtime. Often with a vengeance.

When this happens, your job is to carefully monitory them and guide them upward. The early shoots will be brittle so you need to be gentle with them. But, after a while, you’ll see its large blooms come out.

Clematis Jackmanii Watering

Clematis jackmanii like moist conditions. Just as importantly, they don’t do well if you let them dry out.

This is a risk that can happen during the summertime and very hot climates, especially if you follow a regular watering schedule. As the weather suddenly changes on you, you’re left using a less frequent watering routing.

Thus, best way to water the plant is to allow the top 2 inches of soil to dry before watering again. This reduces the risk of just eye-balling it or depending on the number of days between watering.

When you do water the plant, make sure to water the soil and not dose the plant from above. This keeps the plant dry while giving it moisture. Also deep watering is ideal for this plant, especially when the temperature is very hot.

During the rainy season or colder weather, scale back on watering depending on how much rainfall there is recently and how long it takes the top soil to dry.

Soil

Your clematis jackmanii grows best in moist, well draining soil. Additionally, giving it fertile, neutral to slightly alkaline soil allows the plant to thrive.

Soil should be able to moderately retain moisture and have good drainage. They don’t like poor soil so you may need to amend your garden soil before planting it. Similarly, they struggle with clay (heavy) and sandy (too light) soil.

Using mulch to protect its roots and keep them cool is likewise a good idea. This is especially important since the plant likes sitting under the sun.

Don’t forget to plan out where you want to grow it beforehand. The plant needs enough space depending on how you want it to grow. And, it will be around for decades so a little planning goes a long way.

That said, the clematis jackmanii is at is most stunning when trained to climb structures like trellis, arbors, arches, fences and walls. But, you can also allow them to grow around lower spaces like tree stumps and shrubs. Some gardeners use them as ground cover.

Finally, they don’t mind growing in containers as well. This is a good option if you’d like to enjoy their blooms but live outside of its hardiness zones.

Fertilizing

When it comes to feeding the plant, you have a few choices. The easiest is to use a general purpose fertilizer monthly during its growing season. You don’t need to feed it in the winter.

As with other plants, avoid overfeeding. If at any stage you are experimenting or just starting out with the plant, always be more conservative rather than aggressive with fertilizer. Too much will damage the plant whereas lack of plant food will just slow down its growth.

Besides fertilizer, you can go the organic way. That is, use compost. This is a safer method in that you won’t run the risk of overfeeding. Plus, there’s not residue buildup in the soil.

Compost is always a good idea because it not only improves your soil’s nutrient content but also makes it looser and airy to allow better drainage.

Pruning Clematis Jackmanii

Clematis are pruned based on how they grow, with 3 categories dividing them.

Group 1. Flowers will only grown on old wood (those that grew the previous year). For this group, the best time to prune is after it blooms in the spring.
Group 2. Will flower on both old and new wood (those that grown this season). Here, light pruning is better for woody stemmed clematis. You also don’t want to prune it in the fall or spring. Otherwise it will limit or delay flowering.
Group 3. Flowering occurs on new wood that grew this season. The best time to prune is late in the fall or early in springtime.

The clematis jackmanii falls under group 3. As such, you want to trim it back after it has completed flowering but before it will begin new growth. Here, you want to apply “hard pruning”. That is to cut it all the way to the ground leaving about a foot.

In addition, do remove dead or broken branches.

Clematis Jackmanii Propagation

The best way to propagate clematis jackmanii is through cuttings. To do so, you can take soft or hard cuttings and replant them separately.

The best time to propagate the plant is during early spring or summer. Although, gardeners are likewise successful doing so in the fall.

Alternatively, you can also propagate the plant from seed. Although starting this way takes a lot longer because you need to go through germinations. If you do plan to go this route, using a cold frame helps.

This lets you start the seeds during the cold months so the seedlings will be big enough once last frost arrives to be moved outdoors.

Clematis Jackmanii Transplanting & Repotting

The best time to transplant the clematis jackmanii from its nursery pot is during the spring or early summer. And, when you do, you’ll want to deep plant it.

This puts more soil between its roots and the sun. Doing so also keeps them cool. Since the plant likes full sun, protecting its roots is essential.

Another option to this is to use about 2 inches of mulch. This lets you adjust how much layering to put depending on the time of year.

Likewise, some gardeners grow ground cover around their Jackman’s clematis for this purpose. But, if you decide to do so, make sure to use shallow-rooting plants. Ground cover that grow deep, expansive roots will interfere with the clematis jackmanii’s own root growth. That’s not something you want.

Since the plant is a climber, it is most showy when given some kind of upright structure to grow on. This makes porches, trellises and arbors perfect. They will likewise let you display the plant in its full flory.

Finally, it’s worth mentioning again that planning ahead of time helps.

That’s because the Jackman clematis doesn’t like being uprooted. If you do, it won’t be able to grow as well as it did in its original spot.

Thus, the only reason to transplant it is if it is showing signs of distress or isn’t growing where it currently sits. Once you move it, be prepared to wait about a year or so before it starts growing again. It needs a lot of time to recover from the stress of moving.

Toxicity

Clematis jackmanii is toxic to people and animals, including cats and dogs. Every part of the plant is poisonous. So, you don’t want to mess with it. More importantly, you want to keep young kids and pets away since they’ll sometimes get curious and plant with plants.

Similarly, when working with the Jackman’s clematis, make sure to wear gloves. The plant can cause skin irritation. And, will be problematic if you happen to rub your eyes.

Pests and Diseases

Clematis jackmanii don’t have any major pest or disease issues. However, it has one huge weakness and that is to Clematis wilt.

Clematis wilt is a fungal disease that is deadly for this plant, which it primarily affects. Thus, the name. Unfortunately, there is not known cure for it. So, your best course is prevention.

Like all fungal problems, its cause is from moisture. But, there isn’t much else that’s known about how it comes about. Thus, even moisture and not getting the leaves wet when watering are the two best ways to avoid it.

That said, you its main symptoms are black spots and the plant getting wrinkled. When this happens the only thing you can do is remove the damage sections and how that tis roots are strong enough to withstand the infection. If so, the plant can start to recover by the next season.

As far as pests go, slugs, spider mites and earwigs do the most damage. So, it is a good idea to inspect the plant every so often and treat them when they happen.