Clematis prefer a moisture retentive but not water logged soil and are very tolerant as far as soil
They much prefer either full or part sun and will not do well in full shade.
Less vigorous varieties can be planted in containers, provided they are of a good size, but will need regular feeding to ensure a satisfactory display.
Pruning a clematis depends upon the type of plant involved.
Generally the following applies but it's sensible to check each variety as some have differing rules.
Plants which flower early on last year's shoots:
In the first year, plants should be cut back to about 12" above ground level to ensure that several shoots are produced, thereafter they should be pruned immediately after flowering, but this is only necessary if the plant has become very tangled, otherwise leave well alone.
Large flowered varieties which flower in May and June:
These varieties can be left and only pruned once every 3 or 4 years to avoid bare stems with flowers at the very top. Stems should then be pruned in February to about 2ft above ground level at a strong pair of buds or side shoot.
Plants flowering in late Summer on that year's growth:
In February cut back the old stems to a strong pair of buds around 6" above ground level to avoid a top heavy plant.
Clematis benefit from an annual feed of rose fertiliser in late Winter and this should be followed by a layer of mulch over the roots. In dry spells they appreciate watering from time to time, but make sure it's a good soaking rather than a light sprinkle which tends to draw the roots to the surface and make them more liable to drought conditions.
Clematis prefer their feet in the shade and their heads in the sun, so ideally try to plant them so that their roots are in a cool damp area - perhaps under other bushes or even by placing some slates over the root area but allowing the plant to scramble up into sunshine. They look great when supported by shrubs or even trees, but are not self supporting so if against a fence or wall, trellis or even netting can be used to good effect. In some cases you may need to tie in the new shoots to help them cling.
Powdery mildew, Aphids, Capsid bugs, Caterpillars, Wilting/dieback (which mainly affects the large flowered varieties), Slugs/Snails