The great advantage of a separate cutting garden is that once established you know that there will always be flowers you can pick for the house without having to raid the border. Since the cutting garden serves the specific purpose of supplying blooms for bouquets it does not matter how the plants are arranged or if colors clash which is the opposite of the desired effect of the border. This article by Ciscoe Morris which I found on the Seattle Times website suggests flowers to include and also explains the harmony element.

I CREDIT THE FACT that I?ve managed to stay married to such a good-looking and intelligent woman (you never know who is going to be reading this) because I never fail to surprise her with a beautiful bouquet on her birthday with flowers right out of the garden.

The problem is that it?s difficult to rob my mixed border of its beautiful blooms to make flower arrangements. Fortunately, if you have a little extra garden space, you can create a cutting garden. All you need is an out-of-the-way sunny area with rich, well-drained soil. If drainage is poor, construct raised beds, and fill them with quality potting soil. A cutting garden doesn?t have to be huge: A 4-foot-wide-by-10-foot-long bed can supply all the flowers needed for spectacular bouquets all summer long.

Pick plants that pump out plenty of blooms all season, such as zinnia, scabiosa, salpiglossis and cleome. Perennials that keep producing after cutting include campanula, dahlia, gerbera daisies, evergreen penstemon, phygelius, agastache and salvia.

Leave a little space for a few perennials, with really showy flowers such as delphinium, globe thistle and oriental lilies. They rarely rebloom, but they make fantastic centerpieces for special occasions. Nothing beats a fragrant rose in an arrangement, so add a couple of repeat bloomers in your cutting bed as well. Keep your cutting garden blooming away by fertilizing and watering regularly, and pick your flowers often to promote prolific blooming.

See more at Seattle Times