This cultivar of the clematis was introduced in 1903, and has become one of the most popular clematis ever raised. Clematis may be planted and trained to cover walls, trellis, posts, fences, arbors or to cover rocky sites and can be very useful in these locations to add a touch of color and greenery. This clematis produces masses of 4-6′ beautiful rosy-pink flowers with white stamens July - August. A quick summary of this flower is that it is easily Grown. The plant grows to a height of 2.4 meters. This is a vigorous, bushy plant.

Properties:
Sun Requirements: Full Sun, Partial shade
Hardiness Zones: 4,5,6,7,8
Soil: Grows best in a fertile, well-drained, alkaline soil with a pH of 5.6-6.5. A choice site is key to the success of establishing this perennial; roots should be kept cool and moist.
Clematis do best in neutral or slightly alkaline soils, but they are somewhat adaptable. If you have very acid soil, try to add some calcium when you plant.
Support: It will need support.
Planting: Roots should be planted when the environment is cool and moist, while the vine itself should be in the sun.
Watering: Comtesse de Bouchard requires 1″ of water a week.

Pruning: Pruning late-flowering clematis is easy, and this clematis is no exception. Before the growth happens in early spring, cut back on the stems to a pair of strong buds 15cm to 20cm (6in to 8in) above ground level. An added advantage of this technique is that the clematis growth is removed each spring and so never becomes too much of a burden on its supporting plant, and as a result, the late-flowering clematis becomes useful for training into shrubs, trees and climbing roses.

Adding some white vines to your garden adds a lot of value, and adds a lot of variety. Some of the benefits that vines bring to your garden include:
1. Vines cover the space between fences and grills and bring a sense of privacy to your garden
2. Vines bring a good green effect to the boundaries of a garden, when grown on the edges
3. A flowering vine makes the place seem much more full of flowers and colors
4. Vines can cover an area that is otherwise dull and ugly, or where vegetation finds it difficult to take hold
5. Vines, when grown carefully and allowed to cover the upper part of a garden, bring a sense of a live roof to your garden (you can use them over wooden slats that cover potions of a garden). In times when the sun is harsh, a vine covered roof brings some shade to plants underneath
6. A vine can take a very small root space on the ground, but otherwise reach a much larger footprint over the ground
7. Mixing different types of vines ensures that the garden is always full of flowers; thus making the garden look better and attracting the butterflies and bees to your garden

There must be many more advantages, so if you can suggest more, please let me know.

Passiflora incarnata is different from the other varieties of the Passiflora variety (which are mostly tropical evergreen). Passiflora incarnata is deciduous, capable of surviving winter freezes (very common to large chunks of the United States) and is commonly called passion flower / maypop. Passion flower is commonly found in the southeastern United States and is quite often seen growing alongside ditches by the side of the road, and in sunny and moist places that are fertile.
Passion flower grows to a height of 8-11 feet, and like many other vines, extends tendrils to leverage any support nearby, other plants, fixed structures, to reach the desired height. The plant has large serrated leaves that have two characteristic glands at the base of the blade on the petiole; also, passiflora incarnata has complex flowers that are very beautiful. These flowers have a diameter of 2-3 inches, and have a pattern of white and purple.
The plant looks beautiful, but the vine nature of the plant makes it invasive (it can easily spread in all directions very fast), so sufficient control needs to be emphasized if growing this plant.
The plant has a fleshy fruit called the Maypop; an oval yellowish berry about the size of a hen egg; it is green at first, but then becomes orange as it matures. In this species, the yellow mucilage around the seeds of the fruit is sweet and edible, however it is quite seedy and mostly benefits wildlife.

Growing conditions:
Light: Passion flower Needs part to full sun.
Zones: USDA Zones 6-9. In the winter, the plant dies down to the ground, and like many others, recovers in spring.
Moisture needs: The plant needs a small amount of moisture, and evenly moist soil is the best type for it
Mulching required: Mulching helps
Propagation: Seeds, cuttings

Photo (from Wikipedia)

When you prune, be sure to do the following:
Cut to healthy wood if removing dead, diseased, or damaged growth.
Cut back to a lateral shoot or bud.
Cut to a bud or stem that is pointing in the direction you want the vine to go.
Cut cleanly and don’t leave a stub, which is an invitation to bugs and diseases.
Pruning mature vines can be difficult, because their long stems become tangled. Don’t be tempted to yank. Instead, prune one stem section at a time until you’ve cut out all you want to remove. Check out this very informative site:
http://www.bbg.org/gar2/topics/sustainable/handbooks/pruningtrees/

A query you could have is if you have a large orange trumpet vine, should those vines be cut back to the trellis ?
You can prune trumpet vine anytime. You could probably cut back to 1/2 or 3/4 of the trellis height and still have lots of growth next year.. Here’s a nice website about your trumpet vine:
http://www.beginner-gardening.com/trumpetvine.html