Clematis
Clematis is a member of the buttercup (Ranunculaceae) family, and are very popular  perennial climbing vines that sport beautiful, showy flowers in many shapes and sizes. There are about 250 species and many more hybrids, made up of mostly woody, deciduous climbing plants, although a few are evergreen and a few herbaceous. They flower at different times throughout summer right into the fall. There are three main flower forms:
1. Small white flowers in loose, irregular clusters
2. Bell shaped flowers
3. Flat or open flowers.
The fruit is often showy as well, with ball shaped and feathery. Clematis are generally hardy plants with many being hardy to USDA zone 3, and can survive for 25 years or more.
Clematis, Niobe
Planting Clematis
The best time to plant clematis is in early Spring, but some varieties are OK to plant in the fall. Spring planting is done after all danger of a hard freeze is past, but you should still protect your newly planted clematis from heavy frosts. Once your area frost date is past, your clematis will start putting out new roots and shoots, and leaves will start appearing.
Frost Dates for Canada - Old Farmers Almanac
Frost Dates for U.S. - Old Farmers Almanac
Europe Hardiness Zone Map
British Isles Hardiness Zone Map
Clematis plants may also be available bare root and should be obtained in early spring and planted while still dormant. Some species and small-flowered hybrids have fibrous roots that are susceptible to root damage so disturb roots as little as possible. Choose plants that have multiple stems, healthy, dark green growth and a root system that fills the container. If starting out with small plants, it's a good idea to grow them in gallon pots during the summer so they'll gain some size. Fertilize throughout the growing season and then plant them in the ground in the fall, preferably in early September to allow the roots to get established before freezing weather.
Soil
Clematis prefer well drained soil amended with composted matter. They like neither sandy nor clay soils so if you have either of these types of soil, dig the hole for the clematis vine about 2 times larger than needed and mix in composted soil with your regular soil to get it fertile. Clematis like soil rich in humus and calcium with a pH of 6 to 7. The soil should be kept moist but not wet. Mix the soil dug from the hole with composted manure (hen, cow or salmon) at a rate of 50/50 (50% natural soil from the hole and 50% composted manure).
Planting Instructions
Cut the stems back to 12 inches in height - this helps the plant branch out as it begins to grow and reduces the chance of stem breakage during planting. Plant Clematis with the crown one to two inches below the soil surface and refill the hole with amended soil. You should firm the soil up a bit and then water well to settle the soil around the roots. If planting bare root plants, soak the roots in a bucket of water for an hour to fully hydrate them.
After planting, place a protective barrier around the base of the plant if it might be in danger of getting mowed over or damaged by string trimmers or animals. Since clematis likes their roots to be cool, spread a two-inch layer of mulch or plant some groundcover or low-growing perennials that have shallow, non-invasive roots. Hardy geraniums, creeping phlox, coralbells, silver mound or alyssum would do fine.
Clematis are sometimes slow to get established. In the first season, there may be little growth and few or no blooms, however, it is important to get the roots well established. Fertilize annually for rapid growth during establishment. The ideal N-P-K for Clematis is 15-5-5 fertilizer, and should be spread in a large area around each plant. Once the clematis is established, you may not need to fertilize any more. Plants will need about one inch of water per week during the growing season.
Sun Exposure
The majority of Clematis like their roots shaded and the top growth exposed to the sun. Most clematis require at least 6 - 7 hours of sunlight a day. Varieties with solid colour flowers that like full sun include dark blue, violet and red types. Many clematis can grow well and bloom in semi-shaded places or against a wall facing north (e.g. pastel colored Clematis and some small-flowered species). Diffuse light or northern locations encourage more abundant flowering and better flower color of light-colored or shaded varieties.
Transplanting Clematis
Transplant clematis in the fall, late winter or very early spring before dormancy breaks. Make sure the soil is moist and dig as large of a root ball as possible... the more roots you get, the less shock to the plants system that could hinder growth. Make sure your new site meets all of the plants requirements before moving the plant.
Pruning Clematis
Not all clematis can be pruned in the same way. There are three methods of pruning that can be applied to the major groups of clematis, depending on the time of year the plant flowers.
1. Early-flowering Clematis
Plants in this group bloom in early spring from buds produced the previous season. Prune these back as soon as possible after bloom but no later than the end of July. This allows time for new growth to produce flower buds for the next season. Remove shoots that have bloomed. You can prune out more vines to reduce the size or to form a good framework of branches. Do not cut into woody trunks.
Plants in this group (A) include:
C. alpina
C. macropetala
C. armandii
C. montana
C. chrysocoma
2. Large-flowered Hybrids
Large-flowered hybrids bloom in mid-June on short stems from the previous season's growth and often again in late summer on new growth (these blooms are smaller). Prune in February or March by removing dead and weak stems, then cut back remaining stems to the topmost pair of large, plump green buds. This cut could be a few inches to a foot or two from the stem tips. Plants in this group have the tendency to become bare at the base as they mature. Underplant to help conceal the stems. You may be able to force a flush of new growth from the base by cutting the vine back to 18 inches immediately after the flush of bloom in June.
Plants in this group (B) include:
'Nelly Moser'
'Miss Bateman'
'Lasurstern'
C. x jackmanii
'Duchess of Edinburgh'
'Mrs. Cholmondeley' *1
3. Late-flowering Clematis
Plants in this group flower on the last two to three feet of the current season's growth. Some types begin blooming in mid-June and continue into the fall. This is the easiest group to prune since no old wood needs to be maintained. In February or March cut each stem to a height of about two to three feet. This will include removal of some good stems and buds. Eventually the length of the bare stem at the base will increase as the vine matures.
Plants in this group (C) include:
C. viticella
C. flammula
C. tangutica
C. x jackmanii
C. maximowicziana
'Perle d'Azur'
'Royal Velours'
'Duchess of Albany' *1
**NOTE - See more pruning groups below **
Clematis Diseases
Wilt - caused by the fungus Ascochyta clematidina and commonly called "wilt." It is the most common and damaging problem of clematis characterized by fungal stem rot and leaf spot.
Symptoms include sudden stem collapse, usually when the flower buds are about to open and within a few days the stem and leaves turn black. Only one or perhaps several stems in a plant may wilt. The stem discolors and may exhibit lesions below the first pair of wilted leaves. Any part of the plant can be attacked down to and just below the soil level.
Treatment - remove the diseased stem below the wilted section or even below soil line. Plants usually recover from buds lower on the stem.
Powdery Mildew - caused by the fungus Sphaerotheca pannosa. Causes young leaves to curl and turn purple and the canes may become distorted and dwarfed. If seriously infected, the clematis can die and as well, badly infected buds won't open. Mildew often occurs on plants in poorly ventilated locations.
Symptoms - Leaves, buds, and stems are covered with a white powdery coating.
The white 'powdery' growth on the leaf surface contains thousands of fungal spores which the wind can carry to young leaves. spreading the infection. Mildew develops rapidly during warm, humid weather.
Treatment - a thorough cleanup in the fall and/or spring is a must... rake up and destroy all diseased leaves fallen on the ground. Prune ALL of the diseased stems by cutting several inches below the good stem and then apply a fungicide. Taking these measures will limit the initial growth of fungus. During the growing season, continually clean up and destroy all diseased leaves as new growth is very susceptible. It is very important to thoroughly spray or dust the plant, upper and lower leaf surfaces and the growing tips. Treating the infected plants on a weekly basis should suffice, however during rapid growth or rainy periods, treat more often. Good air circulation is essential so don't crowd amongst other plants and shrubs.
Pests
Aphids - feed early in the season on new growth.
Slugs - attack newly planted plants or even feed on bark of young stems.
Earwigs - feed on blooms and foliage or bore into unopened flower buds.
Rabbits and mice - feed on or girdle stems.
Birds - feed on over wintering buds.
Pruning Groups
Large-flowered Hybrids
* 'Nelly Moser' - 8 to 10 feet in height. Group B pruning.
* 'Barbara Jackman' - 8 feet in height. Group B pruning.
* 'Perle d'Azur' - 16 feet in height. Group B pruning.
* 'Vyvyan Pennell' - 8 feet in height. Group B pruning.
* C. x jackmanii - 8 to 10 feet in height. Group B pruning.
* 'Marie Boisselot' - 8 to 12 feet in height. Group B pruning.
* 'Comtesse de Bouchard' - 6 to 8 feet in height. Group C pruning.
* 'Hagley Hybrid' - 8 feet in height. Group B/C pruning.
* 'Mrs. Cholmondeley' - 20 feet in height. Group B/C pruning.
* 'Niobe'-8 feet in height. Group B/C pruning.
Species and Small-flowered Types
* C. alpina-6 to 8 feet in height. Group A pruning.
* C. alpina 'Candy'-6 to 8 feet in height. Group A pruning.
* C. armandii-15 to 30 feet in height. Group A pruning; can cut to base to rejuvenate vine.
* C. chrysocoma-20 feet in height. Group A pruning.
* C. macropetala-To 15 feet in height. Group A pruning.
* C. montana-20 to 30 feet in height. Group A pruning.
* C. flammula-15 to 20 feet in height. Group C pruning.
* C. maximowicziana-To 30 feet in height. Group C pruning.
* C. tangutica-10 to 15 feet in height. Group C pruning.
* C. viticella (Abundance)-10 to 12 feet in height. Group C pruning.
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