|Crimson Star Clematis|
To begin with, they really do want a minimum of six full hours of sunshine every day. Without that, you'll find the number of blooms will decrease and the plant will not be as healthy. Full sun is excellent. If you grow them in the South, you'll find that a light shade will help the bloom colours from fading.
Having the right soil is critical if you want to succeed with Clematis. This plant adores a rich, organic soil that is heavily amended with compost. There is little point in putting this plant into clay soils as it will not thrive. Similarly, hot sandy soils will not allow the vine to grow to its full potential.
To plant, did a hole approximately two feet by two feet and approximately twelve inches deep. The soil from the hole should be amended with compost before backfilling the plant. I generally use one shovel of compost for every two shovels of original soil.
Carefully take the clematis out of its pot. Cut away fibre pots or slide the plant carefully out of plastic pots. The objective is to minimize root disturbance.
Put the root ball into the hole so the original soil line is approximately three to five inches below your garden soil line. This puts the bud down three to five inches.
If the plant is dormant and the buds are not swelling or showing green, you can backfill the hole to the original soil level.
However, if the plant has any active growth or bud swelling that will be covered over by backfilling to this garden soil depth, you can not cover active growth.
In the case of active growth, only backfill to the original pot soil line. This means you'll grow the clematis in a bit of a hollow for the summer but you'll finish backfilling to the garden's soil line in the fall after the plant has gone dormant.
Our objective is to get that bud down three to five inches but not to cover over growth that will rot or die if covered with soil.
Clematis come with a stake in the pot.
Do not remove this stake on newly planted clematis
Removing the stake can easily lead to the plant flopping about in the wind and breaking something you don't want broken. Remove the stake in the late fall as part of your garden cleanup (you do clean up your garden don't you?) :-)
Shallow Rooted Protection
Clematis are shallow-rooted vines and keeping those roots cool and evenly moist (protected from the hot sun's rays) is our gardening objective. The easiest way to do this is to mulch the plant. Add three to four inches of organic mulch (not rocks) around the base of the plant. Keep the mulch eight to twelve inches or so away from the base of the vines to avoid any rot and mouse damage. (mice sometimes hide in overwintering mulch and chew off tender bark for lunch) Organic mulch is used because as it decomposes, it provides nourishment for the clematis. Rocks do not decompose quickly enough to be of benefit to the plant. :-)
Do water at least weekly and do water deeply. Remember this plant likes even moisture so check under the mulch during the heat of the summer to ensure the soil is damp. Do not plant this vine where the ground is wet as winter wetness will rot it off.
These vines are heavy feeders. I like to use compost every spring with several shovels full being applied around the base of each plant. And when the new vines are two to three inches long, I'll usually give them a boost of fish food emulsion.
The nitrogen in the liquid emulsion really gets those vines growing. I note that feeding a high nitrogen chemical food (a little too much nitrogen) may stop blooming rather than enhance it because you'll grow huge vines at the expense of flower production.
Clematis is a vine so they do need some kind of support in most garden settings (I have grown them and simply let them wander around and over the perennials; it is an interesting thing to do).
You'll require trellis or arbors for support or even nearby shrubs. I once used a Beautybush as a support for a yellow-flowering C. tangutica and after three years you couldn't see the shrub (it had died because the clematis shaded it out).