Clematis require about 6 hours of full sun per day to grow best although some light shading during the hottest part of the day is beneficial. It is essential for the roots to remain cool and moist, so protect them with a heavy mulch, the shade of low growing plants, or even a large flat rock. A few of the very large flowered varieties should be planted in a more easternly exposure, to prevent excessive flower fading caused by to much sun. Clematis likes peaty soil, but you must add enough lime to ensure the soil is not to acidic. Generous amounts of bone meal and compost should be added to the soil, but only cultivated in shallowly.
Clematis flowers form either on the current season's growth or on that of the previous year.
Jackman clematis forms its buds on the new growth. This type of Clematis have a tendency to become bare at the bottom of the vine unless pruned annually in late winter or very early spring. Cut these plants back nearly to the ground, leaving at least one pair of healthy looking buds on the trunk. Most clematis will require staking so the twining leaf petioles can cling and climb upward, although it is not a problem if you choose to let the plants sprawl over the ground, fences, or whatever. About the weather,,,Hmmmmmmm.