Many leading garden designers do not always follow color rules. They begin planning with a few basic colors and build from there. Much like paint, flower and foliage colors will affect the appearance of what they are planted next to. One way to test their effect is to place plants side by side while still in their containers. Move them around the garden until you find a suitable position. Within each color are many shades and hues. Color descriptions on plant labels can be misleading. The eye is more discerning, so buy plants in bloom whenever possible. It is important to gauge which plants will be in bloom at the same time. It is possible to have several distinct color combinations at different intervals throughout the season.
On the color wheel, yellow is a primary color, but in the landscape it is used like a complimentary color. In its paler hues it is a perfect background color for purple or orange. It can also be blended with lavenders and blues for a cooler feel. When brighter yellows are used, they stand alongside hot colors like orange and red. Yellow flowering plants to include in the landscape are: rhododendron, rose, evening primrose, daffodil, tulip, daisy and coreopsis. Dark foliage will bring out yellow flowers, but lighter foliage can muddy them. Choose purple flowers with yellow eyes to blend with true yellow flowers.
Purple is a secondary color, so it can have red or blue tones. True purple is an intense color that will immediately catch the eye. Although it commands attention, it has a soothing effect on the senses. In its lighter hues it brings out other tones and blends well with yellow. Lavender-flowered plants are good background plants to use in large swathes. Shrubs like hydrangea, lilac and rhododendron have good purple varieties. A number of herbs have purple flowers such as lavender, salvia, purple coneflower and violet. If you like wildflowers, you can find a wide assortment of purples as well as orange and yellow.
Orange can be one of the more difficult colors to place in the landscape. It is very dominant and can clash with some colors. Don't fight this -- place orange where it can shine. Strategically place it at a distance from conflicting colors. Yellow is a transitional color that can be placed between orange and other colors. If you want purposeful contrast, place orange right next to deep purple flowers. A cluster of orange Exbury azaleas makes a strong statement in the spring garden, or plant repeat-blooming orange roses where you want ongoing color. Orange summer perennials are daylily, rudbeckia, crocosmia or geum. Good filler plants are annual calendula and nasturtium.