How do you grow your climbers? Against a trellis, covering a fence, over a pergola? While there is nothing wrong in this approach, why not mimic what climbers do in the wild, and give them another plant as a host? If you decide to adopt this approach, there a few points to consider.
Firstly is competition. Shrubs and trees are there for the duration and grow relatively slowly. Climbers on the other hand want, and need, to reach the light as fast as possible. It’s comparable to the tortoise and the hare. In order to prevent the host from being swamped, it needs a head start of a few years to build up a decent size before planting the climber. By then, the hosts roots will also have made the most of the surrounding soil, so the climber will need to be planted just beyond their reach and trained back towards the host.
Secondly, size matters. However much of a head start it has, a small shrub will soon by overwhelmed by a vigorous climber. Clematis montana will smother anything less than twenty feet tall as soon as your back is turned. So match the host and climber to achieve the best results.
The third point to consider is pruning regimes. A spring flowering shrub will need reducing just as a late flowering climber is getting into its growing stride. However, a late flowering shrub can be cut back in spring, immediately after a winter flowering climber has finished it display.
You can match the flowering times of the two partners, or you can pick ones that bloom at different times of the year, getting two seasons of interest from a space. The choice is yours. If you go for the former, should you match the flower colours or pick differing ones? Again, the preference is personal. I prefer to go for contrasts so it is obvious there is more than one plant. Here are a few examples that have worked well for me:
Clematis ‘Kaiu’ clambering into physocarpus opulifolius ‘Diabolo.’ The flowers of the clematis are quite delicate, and the dark leaves of its host show up the pale colouring well.
Similarly, the bright flowers of clematis texensis ‘Gravetye Beauty’ are highlighted against the foliage of physocarpus opulifolius ‘Dart’s Gold.’ Training clematis into trees was less successful as the flowers were only carried at the top of the hosts, too far away to be appreciated.
On a smaller scale, euonymus fortunei’ Silver Queen’ is a good host for clematis ‘Arabella.’
This is a shorter clematis that flowers for several weeks from early summer, and the smaller shrub is the right size to host it.
Finally an accidental combination that has worked out well for all concerned. I planted two wisteria to climb over a broad arch, but they both preferred next door’s conifer.