How to Grow and Care for Jackman's Clematis

Jackman's clematis is one of the most popular of all flowering vines—so commonly grown that some gardeners despise it for its very popularity. But popular plants generally gain their popularity for good reasons. Jackman's clematis is a vigorous yet compact vine with fabulous flowers. Its large 5 -inch blooms are a delicious dark purple, making it on of the prettiest flowering vines. Clematis vines are often used to camouflage eyesores in the landscape, or for landscaping around mailboxes, where the vine is trained up a mailbox post as a decoration. It can be trained up almost any vertical structure, from garden walls to small trees.

Clematis can be planted in the spring, late summer, or early fall. 

Jackman's Clematis Care

This vine is fussier about the way it is planted than most plants. It is best planted so that the top of the root ball is a full 3 to 4 inches below the level it was in the nursery pot. Planting at this depth promotes the development of "latent" buds below ground level. Their presence is your insurance policy against the clematis wilt disease that sometimes infects above-ground vegetation.

This perennial is a true climber. It will twine its way around any support (trellis, etc.) that you provide for it. A wide variety of structures can serve as support for the vine's vertical growth, whether they are existing features in your landscape or features that you create specifically to showcase the plant. Many growers train their clematis vines to climb upon other plants (shrubs and vines, mainly). Just remember to clean up in fall by cutting back this growth, which will allow you to "hit the reset button" for next year.​

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; in the south, it is a good idea to give it partial shade.

Soil

Jackman's clematis prefers fertile, well-drained soil. A major soil consideration in growing Jackman's clematis is to keep the soil relatively cool.

Water

Do not let the soil dry out completely at any point during the period of active growth for the plant. It very much prefers consistent moisture.

Temperature and Humidity

While Jackman's clematis likes warm weather, it does not do well in excessive summer heat, especially if it is planted in a location where the root zone gets hot. It does not have any particular humidity preferences.

Fertilizer

If you are an organic gardener, fertilize the clematis with compost. Otherwise, apply a complete fertilizer each spring, then monthly through the growing season. When using commercial fertilizers, err on the side of too little rather than too much.

Types of Jackman's Clematis

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

• C. 'Etoile Violette' has smaller blooms than Jackman's clematis and blooms through the end of the summer.
• C. x Durandii is a non-twining clematis that will sprawl over the ground unless manually tied to a vertical support. It blooms for a remarkably long time, through the entire summer and into fall.
• C. 'The President' has huge flowers that bloom twice—in late spring and early summer, then again in late summer and early fall. Vines grow as much as 10 feet tall.
• C. macropetala 'Maidwell Hall' has smaller, nodding flowers with white centers. This easy-to-grow vine has a maximum height of 6 to 8 feet.
• C. 'Venosa Violacea' has large 6-inch flowers with petals that are white with purple margins. It grows 9 to 12 feet tall.

Pruning

For pruning purposes, Jackman's clematis is considered a "class 3" clematis that blooms on "new wood"—producing flowers on stems that have grown in the current growing season, not last year's growth. This means that the best time to prune the vine is from late fall to early spring, after flowering is complete but before new growth has begun.

It is best not to prune a new vine very much, giving it time to put on some growth (unless it is to remove dead branches, which can be done at any time) But once it matures, a clematis may begin to lose vigor or become overgrown, and this is the time to begin an early spring pruning regimen. While some perform a drastic pruning, most growers prune clematis in a more targeted fashion, cutting the vines down to a preferred height where there are good leaf buds present.

Propagating Jackman's Clematis

Clematis can be propagated with cuttings made from new, soft green growth.

1. Take a cutting below a leaf node. Your cutting only needs one leaf stem, so trim off any extras.
2. Dip the cut ends in rooting hormone. Fill a 4-inch pot with potting mix. Lay the cuttings on top horizontally. Lightly cover with potting mix and moisten the top with water.
3. Place the pot in a clear plastic bag and keep it in bright but not direct light, Keep the soil evenly moist but not soggy. In about four weeks, the cutting should have rooted. You'll see new growth and the cutting won't wiggle when you gently tug on it.
4. Transplant each rooted cutting in its own pot. Leave it in the pot for another growing season and harden it off before transplanting it outdoors.

How to Grow Jackman's Clematis From Seed

This variety is a hybrid and seeds collected from it won't produce plants that are true to type. Therefore growing it from seed is not recommended.

Potting and Repotting Jackman's Clematis

Due it its size and fast growth rate, Jackman's clematis is not the best clematis to grow in a container. A non-vining, bushy clematis such as Arabella clematis (Clematis x 'Arabella') is a much better choice for pots.

Overwintering

Jackman's clematis is a hardy plant but it still needs winter protection in the form of mulching. Apply a layer of at least 2 to 3 inches of mulch around the base to protect the roots from the freezing temperatures.

Common Pests and Plant Diseases

Slugs like to eat clematis almost as much as they do hostas. If you use stones to shade the base of the plant, lift them often to check for slugs napping beneath. Dispatch any slugs that you do find. Pest damage can also come from earwigs and spider mites.

Clematis wilt, a fungal disease that attacks the base stems of the plant, can be fatal to clematis. Its symptoms are a sudden progressive shriveling of the entire plant, usually in early summer. Black spots on the leaves may be evident. There is no cure for clematis wilt, but you may be able to prevent it by keeping the soil evenly moist, making sure the soil is neutral or slightly alkaline, and watering at the base of the plant rather than on the leaves.

If clematis wilt appears, remove all damaged portions of the vine. If the root system is strong, the plant may recover by the next season.

How to Get Jackman's Clematis to Bloom

If your clematis is not blooming, it could be improper pruning, too much nitrogen fertilizer, drought stress, or too little sunlight, Make sure to prune in the fall or winter, use a fertilizer high in phosphorus, and give the plant enough water. As for sunlight, check if surrounding plants cast too much shade on it, which can be often remedied by pruning them.

Common Problems with Jackman's Clematis

The roots of clematis do not like heat so It is critical to shelter clematis roots from the blazing sun. You need to take measures to keep the roots cool. The practice of deep planting helps keep the roots cool. 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, which is not ideal because they can interfere with the root system of the clematis. Still others place flagstones or other objects at the base of the clematis to cast shade. However, the latter practice can provide an open invitation to slugs.