The lilies are about the flowers, bold and illuminating the landscape the way few other perennials can. They do tend to add a boisterous element, so you should be okay with that. From a design standpoint, lilies have to be used with a painterly eye or they will overwhelm the garden. But man they are winter hardy. Oklahoma City is an excellent choice for northern gardens, surviving temperatures to -35 degrees Fahrenheit.
Gardeners reportedly grow Oklahoma City Asiatic Lily in Alaska.
Oklahoma City, typical of the asiatic lilies, grows 3′-5′ and blooms reliably in late Spring. Flowers are beacons and large, to 6″ or so across. Plant asiatic lilies here and there throughout the garden. Ideally, they appear as if they’ve just erupted out of the landscape.
Should you choose to grow an asiatic lily such as Oklahoma City, the main thing, as with most bulbs, is good drainage (crucial in winter). Provide moderate to full sun, neutral to acidic soil and don’t plant them upside down and you will generally succeed.
It is recommended to plant asiatic lilies where the top of the plants get sun and the bottom stays cool (similar to clematis). Considering their height, planting in the middle or back of the mixed border should easily meet this preference.
Many serious lily growers plant them in raised beds. While this is excellent practice, I would not recommend going to such lengths for the gardener who merely wants a splash of color about the mixed garden. I am a proponent of preparing beds well prior to planting anything, and so truthfully rarely do we experience drainage issues in our landscapes.
I’ve never watered a lily during summer, nor would I. Asiatic lilies are generally tough, resilient plants once established, and in our gardens we firmly believe in survival of the fittest. The more we can forego planting gardens that need supplemental watering, the better.
Plant Oklahoma City 6″ deep and 18″ apart. An excellent resource for lily culture can be found in Mike’s Backyard.