Clematis Jackmanii — care and pruning

There is no such amount of contradictory and simply incorrect information about any clematis or clematis as about Jackman’s clematis (Jackmanii). It’s all about the constantly changing classification of varieties and the popularity of the “Jackmanii” variety itself. So I wrote this article to break it all down Thus:

  1. Clematis Jackman as a species does not exist and has never existed.
  2. The Jackman or a Jackmanii has only existed within the outdated classification of clematis. It included varieties obtained by crossing Clematis vitalba and varietal clematis of the Patens group. At the moment, the group is eliminated due to the inability to accurately determine the origin of many varieties, as well as due to the fact that many varieties have a complex origin. Now within new standard Matthews classification, the Jackmanii group is consolidated with the Lanuginosa group into one common large group “Late-flowering large-flowered clematis”.
  3. There is also a variety of clematis “Jackman” or “Jackmani”, which is part of a new group of large-flowered late-flowering clematis. Below you can find description, photos and information about blooming season, growing conditions, pruning group of the Jackmanii clematis as a variety.

Clematis Jackmanii

The variety of clematis “Jackmani” was bred by the British florist George Jackman (Jackmanii) Jr. in 1858 as a result of crossing Clematis lanuginosa and the variety Clematis diversifolia “Hendersonii”. The first flowers appeared in 1862, and already in 1863 the variety was introduced. So this is the modern vision. However, in William Robinson’s book “The Virginia’s Bower”, published in 1912, the following is written about clematis Jackmanii:

“This plant, according to Monsieur Lavalli, is a Japanese species, and not a hybrid, as previously assumed. And this is the fact, because this plant is well known to botanists who made collections in Japan.”

The quoted above is completely wrong: the records of Jackman’s breeding work have been preserved and they confirm his authorship. Nevertheless there are other arguments. The caption under Mike Denny’s photo, which depicts an old plant says “the result of cutting a twenty-year-old plant that was carried out 30 years ago.” Mike’s father, Vince Danny, considered this plant a specimen of the variety. Then English text is unreadable , but it is noted that the plant shown in the photo is common in Japan.

In fact, none of these forms is the original clematis “Jackmanii”. In the 2005 edition of the British Clematis Society Journal, Wim Snoijer wrote that the modern clematis “Jackmani” does not resemble its description and image in the classic 1872 book “Clematis as a Garden Flower”, written by Moore and Jackman and has withstood many reprints. However, modern samples correspond to the herbarium of 1881. From this we can conclude that the original clematis of Jackman has been lost for a very long time.

Clematis Jackmanii description

Jackmani clematis forms shoots up to 14 feet (4.5 meters) long, usually about 9 feet (3 meters). The growth rate and shoot-forming ability are average. Leaves up to 6 (9) nodes are trifoliate or nonparnoperistosyllabic, with 5 leaflets. The length of the leaf is 4.5 … 10.5 inches (17… 27 cm), including the length of the petiole 2 … 4 inches (7… 10.5 cm). The width of the sheet is 19…25 cm. The leaflets are simple whole, the terminal ones are sometimes dissected, lobed or separate. The shape of the leaflets is ovate or pointed-ovate. The tip of the leaflet is pointed or oblong-pointed. The length of the leaflets is 7…10.5 cm, the width is 4…8 cm, the length of the petioles of the terminal leaflets is 3…6.5 cm, the lateral ones are 2…4.5 cm

Clematis Jackmanii Images

Clematis Jackmanii vs The President

Params Jackmanii The President
Height 8′ – 12′ (240cm – 3.6m) Height6′ – 10′ (180cm – 3m)
Flower Size 10…15 cm 15…18 cm
Tepals 4-7.5cm long, 3-5cm wide, obovate or rhombic 6-8; 6.5-8.5cm long, 3.5-4.5cm wide, ovate to elliptic
Tepals color Violet Violet
Anthers color White or beige Red
USDA Zones 4-9 4-9

Сlematis Jackmanii bloom time

In my region, clematis “Jackmani” blooms on shoots this year from July to the end of September, blooming is abundant. The same blooming seasom of this clematis in the states of Vermont, Oregon, Michigan, Montana, etc.

Peduncles 20…24 cm long are formed on the upper 7 nodes of the shoot The buds are oblong-ovate, grayish-purple, usually directed downwards or to the side. The flowers are large, 10…15 cm in diameter, with 4-6 diamond-shaped sepals with a pointed end. The length of the sepals is 5…7.5 cm, width – 2.8…3.8 cm The color on the inside is dark purple with purple veins, eventually becomes purple. From the outside, the color is smoky purple with darker veins. The length of the stamens is 1.2 cm, including anther 0.5 cm. The staminate filaments are grayish-green, the anthers are light, the ligament is light green. The fruit is a nut 0.6 cm long, 0.7 cm wide with a 2.5 cm long spout. The nuts are collected in a multi-nut.

How tall does jackmanii clematis grow? How fast does jackmanii clematis grow?

In the early years, clematis Jackmanii rarely grows to 6 feet tall. Then it all depends on how good the cultivation conditions are. In one location, such a clematis, growing for more than 10 years, almost reached the top of the second floor.

Where to buy?

In case you are located in the UK, you definitely will not have any problems with buying clematis Jackmanii, it is available in almost all nurseries and garden centers. It is not so easy to buy this clematis, but it is on AmericanMeadows and presumably retailers have it . It can be definitely found at many American collectors.

Clematis Jackmanii care

I don’t have this clematis in my collection right now, it’s left in the old garden, which I don’t have access to right now. However, it had been growing near my fence for many years and I know well how to grow clematis Jackmanii. In addition, I observe several vines that grow in the neighborhood.

Сlematis jackmanii growing conditions

Hardiness 4-11
US states, where clematis grows well Oregon, Utah, Washington, NewYork, Michigan, California, Minnesota, Wisconsin, Arizona, Colorado, Connecticut
Heat Zones 1-9
Plant Type Climbers
Plant Family Clematis
Exposure Full Sun, Partial Sun
Water Needs Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Tolerance Deer

When to plant clematis Jackmanii

If you live in a state where there is a cold winter – for example, in New York, Oregon or Wisconsin, the best time to plant clematis is autumn. At low air temperature, the aboveground part of the clematis almost does not grow, but the roots develop well in cool soil. Therefore, clematis planted in autumn has time to prepare for winter and begins to grow actively in spring.

One can also plant clematis Jackmanii in early spring, until the stems and leaves begin to grow rapidly. The earlier in the spring you plant a plant outside, the more time it will have to form a root system.

If there is no other possibility, then you can plant clematis in the summer, but very carefully – you just need to transship it with a lump of soil so as not to damage either the roots or stems.

If you are living in a state or region where there is no distinct winter, the best time to plant clematis is when the temperature of the air and soil decreases at least a little.

How to choose a place planting?

It also depends on which state you live in.

I live in a region whose climate roughly corresponds to USDA Zone 5 or 6. We have quite a lot of cloudy days, cold north-westerly winds often blow. Therefore, I have the best place to plant clematis Jackmanii — to the east, southeast or south of the wall or other covering.

If you live in a place where strong winds are rare, but there is a lot of sun, you need to choose a place so that the plant is protected from sunlight in a hot afternoon.

In general, the place for planting should be:

  • properly lit;
  • protected from strong wind;
  • protected from flooding;
  • protected from hot midday sunlight.

If you live in a region with cold winters, the distance from the center of the pit to the foundation of the wall should be at least 50 cm, so that the roots of clematis do not freeze in winter Clematis Jackmanii is hardy, but in severe frosts some of the roots may suffer from close contact with the frozen ground.

The best soil for planting clematis

The best soil for growing clematis Jackmanii is light loam or cohesive sandy loam. In general, it should be light, breathable, highly fertile soil with a large amount of humus. Clematis grows very poorly on heavy soils in which there is little air. Such soils can be improved by adding organic fertilizers.

It is better if the soil is slightly alkaline, because soil fungi that cause clematis wilt develop worse in such soil. Neutral or slightly acidic soil is also suitable.

How to plant clematis Jackmanii

It is better to prepare a pit for planting 2 weeks or earlier before planting. This is necessary so that the soil has time to settle.

The size of the pit is not less than 1.5×1.5×1.5 feet (approximately 45x45x45 cm). Such a large pit is needed because in the first years the root system of clematis will grow and develop only in it.

The soil extracted from the pit should be mixed with humus or compost in a ratio of 1: 1. There you also need to add a complex fertilizer of prolonged action, such as Osmocot or if you don`t have such a fertilizer, ordinary superphosphate – about 1 … 1.5 ounces.


Even if the soil is heavy and dense, it is impossible to fill the pit with looser soil. In this case, all the rainwater will accumulate in the planting pit, and the clematis roots will begin to rot.

If the clematis that you plan to plant doesn`t grow fast, it is better to break the clod of soil before planting and carefully wash the roots of the seedling. Check them. Rotted or damaged roots should be cut off, and the root sections should be sprinkled with a mixture of fine sand and ash. Then it is worth pouring all the roots with this mixture to protect the clematis from wilt.

Is it allowed to bury clematis Jackmanii when planting?

It is, if the lower part of the stem is lignified. You can bury it to the depth of this lignified part. But if the plant is new and its stems are green from below, you can not bury it.

Place the clematis in the planting pit so that it is 2 inches higher than the intended one. Now fill it with the prepared soil mixture. Having completely filled the pit, tamp the soil and water clematis abundantly so that the soil fits snugly to the roots.

Care for Clematis Jackmanii

The care is the same as for other large-flowered clematis – you can read about it in detail in my article Clematis care – how to get abundant flowering and protect clematis from diseases. Here I will describe it briefly:

  1. Clematis Jackmanii should be watered only in severe drought, rarely, but abundantly. Under a young plant, at least 1 gallon of water should be poured at a time, under an adult – at least 2 gallons.
  2. The soil around the clematis should be kept clean of weeds and regularly loosened to a shallow depth.
  3. Сlematis Jackmanii fertilizing. In the first year after planting, the Jackmanii clematis is not fertilized Starting from 2 years after planting, it is necessary to ferilize the plant at least 3 times per season: in spring when the stems grow, at the beginning of bud formation and at the end of summer. In the first top fertilization, a complex fertilizer with a predominance of nitrogen is used, in the second – a complex fertilizer with a predominance of potassium and phosphorus, as well as with trace elements, in the third – a phosphorus-potassium fertilizer without nitrogen.
  4. If you grow clematis based on a smooth trellis, it should be regularly tied up in the places where you need it, not the vine.
  5. Autumn pruning is very important.

Сlematis Jackmanii pruning

When to prune clematis Jackmanii?

Clematis should be pruned in autumn, when the growing season is almost completely over and cold weather is approaching.

Сlematis Jackmanii pruning group

Clematis Jackmanii belongs to the 3rd pruning group (strong pruning). This means that in the fall it is cut short, at a height of 1/2-1 feet above a pair of strong buds. If you live in a region with very cold winters, cut stems should be covered for the winter. If you don`t have a temperature below 5 °F, you can simply pour a bucket of dry peat or use another similar option as a shelter on the trimmed tillering node.


Is Jackmanii clematis deer resistant?
Clematis Jackmanii is resistant to deers and rabbits. Deers and rabbitis don`t like this vine.

What is the difference between clematis ‘Jackmanii’ and ‘Jackmanii Superba’?
Clematis ‘Jackmanii Superba’ has wider sepals than Clematis ‘Jackmanii’. ‘Superba’ has red stripes on the sepals immediately after flowering, which is not the case with ‘Jackmanii’. Over time, these stripes disappear.

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