I like to compare the skill and the art involved in setting up a planter to that of flower arranging. The vast majority of us have at sometime placed a couple of flowers in a vase and enjoyed the results. Some of us have taken a bit more time and arranged the flowers so that they show themselves off to best advantage. A smaller number of us really go to town on flower arranging and are always searching for new flowers or foliage and unusual vases and vessels. There is a lesson that should be learned from the "go-ahead" flower arrangers, and I do believe gardeners could do worse than borrow some of the energy and ideas. But the flower arrangers have a simple time compared to the planter gardener. They've got the advantage of being able to place their arrangements out of the way of strong winds, baking sun and drenching rain. Florists can always work happily in the knowledge that what they arrange will stay basically the same for the lifetime of the display.
The planter gardener - with a few exceptions - has to possess a vision of how a display will look several months on, when the planting matures. The few small plants planted at the beginning of the season will grow and by the end of the summer there will be a planter burgeoning with flowers and leaves.
In the meantime, you have had to water, feed, prune and pinch out as well as do battle with the pests and diseases that do their best to thwart your efforts' It is not off-putting; its gardening.
Colour
Plants in pots are in intimate contact with one another and their area of display is confined. So, in container plantings, the subtle colour details and mixtures that may easily become lost within a border setting are there to be appreciated, right before you.
If you are unsure about how to use colour in your planters, get inspiration from lifestyle and interior magazines and convert what you discover there into ideas for plant and planter colours. And try these colour combinations that I find work fine. I find white is very versatile: with green it achieves a unique freshness;
Combined with yellow and green it really is cool and lively; with pinks and blues it has a romantic feel; also it really sets off bright colours such as oranges and reds.
Purple works in many combinations: with grey and pink its sophisticated; with yellow more light-hearted; with brown it's sombre but classy; with crimson it will appear regal; with orange, jazzy; and with white, cool. Blue as a flower colour is in short supply, however any element of blue in any planting is eye-catching. Reds, yellows, and oranges are ideal for flamboyant displays; with magenta and violet they create vivacious mixes.