Clematis Culture and Care

Vines and Shrubs-Adding Elevation and Structure to the Garden

Clematis are climbing or creeping plants that produce stunning blue, purple, pink, rose, yellow or white flowers.   Some may bloom all summer and into the fall, while others are early spring bloomers. Certain cultivars can grow up to 20 feet (6.1 m) tall and live for over 80 years. Clematis enjoy full sun on their foliage and cool shade over the roots in order to thrive.  They perform quite well in partial shade or half day sun.

Siting your plant’s location in the garden is important.  Look for a spot with low-growing perennials or ground cover that will shade the roots, but allow it to grow into full sun.  Clematis roots enjoy a cool, damp location  and sunlight on the vine and flowers.  Clematis may be sited near the base of a shrub or small tree. Plants will grow up the branches without harming the “companion” shrub or tree.   The location shouldn’t be so dry that it doesn’t retain moisture, but should drain well enough that standing water doesn’t sit around the roots. To test whether the soil in an area drains well, dig a hole and fill it with water. If the water drains immediately, the soil may dry too quickly. If the water stands in the hole, the soil may be too dense and may not drain fast enough. A hole in which the water slowly seeps into the soil will likely work very well for growing Clematis.

Clematis prefer the soil to be neutral or alkaline over acidic. If you conduct a test and determine that the pH is a little too acidic, sweeten the soil by mixing in limestone or wood ash.   Before you planting, amend the soil by working in compost and granular organic fertilizer.  This will ensure that the plant has enough nutrients to establish itself in the first few months after planting.  If you’re working with soil that tends to be clay heavy (slow to drain), dig the hole a few inches deeper than you normally would and add organic material to the bottom. If your soil is sandy (quick to drain), adding a bit of clay based soil and organic material will be appreciated.

Clematis may need to be fertilized from time to time if soil fertility is low.   Avoid using high nitrogen fertilizers (high first number in the series of 3).   Generally bulb fertilizers and slow release formulations are best.   Only fertilize established plants and those that show signs of need.

Dig a hole several inches deeper than the container the plant came in, so that when you plant it the soil buries 3 to 4 inches of stem.  Deep planting insures that the crown of the plant is protected from above ground stem damage and disease (often common with Clematis).  Very gently remove the clematis from the pot it came in, taking care not to rip or break the fragile roots and shoots. Set the root ball into the hole at least 3 to 4 inches below the surface and pat the soil around its base stem.  Planting Clematis deeply insures that they will survive any surface damage that may occur to the stems. Leave the stake in place so that the young clematis has something to grow against for the first year.  Place 2 to 3 inches of bark mulch around the base of the clematis to keep the roots cool. You can also plant or encourage the growth of low-growing perennials whose leaves will shade the roots of the clematis throughout the summer.

Give the Clematis long, deep drinks of water whenever the soil seems dry. To test whether it is dry, stick your finger in the soil, then pull it out. If you didn’t hit moist soil, it’s time to water the plant.  Avoid watering foliage, as this may encourage disease.  Water in the morning, rather than in the evening, so that the water has time to dry and be absorbed before night falls.

Many vine Clematis require a vertical structure on which to climb.  This can be accomplished with a trellis, wire fence attached to a post or any other number of structures that provide small attachment points for leaf petioles to wrap around.  During the first year, the support that came with the Clematis will be sufficient for the plant’s needs, but after that you’ll need to provide a larger support to encourage it to grow bigger. Clematis grow by twisting its leaf petioles around slender supports like twine, fishing line, thin branches, or wire. Be sure the support you provide isn’t too wide for the leaf stems to reach around. It should be less than .5 inches (1.27 centimeters) in diameter. If you have a trellis or arbor made with wide pieces of wood, line it with a wire or attach some fishing line to provide a support thin enough for the clematis to wrap around. As the Clematis grows larger and reaches around the support, you can help it stay in place by “trussing” it: loosely tying it to the structure.

While clematis aren’t prone to being affected by pests, they can get a fungal disease that can cause a stem or two, or the entire plant to turn black and die. If you see a dead or wilting stem on the clematis, use a clean pair of pruning shears to trim it away at the base (below the base of the stem disease). Disinfect the shears in a bleach solution between cuts so you don’t spread the disease to other parts of the plant.

In warmer climates certain types of Clematis will retain their woody stems through winter and as they age over the years become less productive.  In cases of where old woody stems are evident, carefully cut these out to ground level to encourage new vigorous growth.

Most Clematis does well with an annual pruning to encourage fresh growth. However, different cultivars require pruning at different times of year. It’s important to know exactly when to prune your specific cultivar, since you can damage the plant if you prune it at the wrong time of year.  Most bush or creeping types are cut to the ground each spring season and will renew their stems each year.

Pruning requirements.

Clematis Prune 1

Lightly prune after blooming. This group of Clematis blooms in spring on the previous year’s growth. Prune just after flowering by removing any weak or dead stems, then lightly shape and guide vines if needed.

Clematis Prune 2

Repeat bloomers with first flowering on previous year’s growth, then rebloom on the new growth. In early spring, when buds begin to swell, lightly prune if needed to shape vines. After the first bloom, give another light pruning to increase later blooms.

Clematis Prune 3

Summer and later flowering types on new growth. Hard prune in early spring as new leaf buds begin to swell low on the plant. Trim to 8-12″ tall, to a pair of strong looking buds.  This includes group is mainly comprised of Clematis integrifolia and its hybrids; all viticella cultivars; texensis hybrids.

Like all plants, each Clematis cultivar will perform differently in variable conditions.  Plant habits, growth rates and ease of culture are wide ranging and a single set of rules does not fit all.  Experiment with their location and growing structures. these interesting plants provide a multitude of enjoyment in the garden and are valuable accent plants.