Jim Gerdemann is a retired botanist and Professor Emeritus of the University of Illinois, and Janice Gerdemann is a retired teacher: both have a life-long passion with gardening. In the 1970s they bought land near Yachats, OR, on the lower slope of Green Mountain where good cold air drainage help to provide a mild microclimate in which to raise and experiment with a wide variety of native and non-native species. A spring and small stream provide enhanced beauty and interest throughout the year. The site is home to a wide variety of wildlife. Black-tail deer, North American Elk, raccoon, black bear, cougar, coyotes and one bobcat have visited. The rare Giant Pacific Salamander (7 to 8 inch long) has been sighted three times. The property boasts a wide variety of birds, including wrens, hummingbirds, warblers (five species), kinglets, chickadees, nuthatches, woodpeckers (including the pileated), and raptors. The Gerdemann Garden is now twenty-five years old.

Although a few trees were removed to provide adequate sunlight, most of the trunks and limbs were left in place to decay and provide "nurse logs," as in a natural forest. Invasive exotics such as blackberry, broom and English Ivy are not tolerated. All of the native flowers, such as Trillium, Iris, Viola, Columbine, Erythronium, Camas, Bleeding Heart, Western Lily and others are encouraged.

The original plantings were mainly Rhododendrons with a concentration on species and hybrids that are not commonly cultivated in Oregon . Many of these are borderline in hardiness, such as species of Maddenia, Arboria, Grandia, Falconera, and Vireya. Gerdemann also has planted some older and seldom-obtainable English Rhododendron hybrids. In addition, he has hybridized and named several new plants, including the series of semi-hardy Vireyas that he calls "Tropic Alpines" and that can be grown out of doors in many coastal areas.

Gerdemann also has planted species not typically grown in Oregon, such as the New Zealand tree ferns; protoaceae such as Australian Grevillia and the Chilean flame tree; and the Chilean Lantern Tree. He has included other Southern Hemisphere species throughout the garden. Presently, he is evaluating several palm tree species. Because of the garden's good microclimate, Dr. Gerdemann has been able to grow many plants of borderline hardiness (including, for example, most Maddenia and a few Vireyas) without protection.

In fact, Gerdemann's experiments with non-native species gives other gardeners knowledge about what plants will thrive in the Pacific Maritime climate and soils. Furthermore, they have done this while maintaining all the native species in their almost four acres, giving special attention to planting around fallen trees and other natural features. Essentially they worked with the land instead of imposing a pre-conceived design on it. Many of their flourishing experiments now grace others' gardens. Today, the Gerdemann Garden contains approximately 60 native species, 266 rhododendron species, over 350 hybrids, 424 species of trees and shrubs, and many perennials.

Many species are represented by more than one form. For example, there are 21 forms of Rhododendron arboreum.

Most importantly, from its inception, the Gerdemanns have always shared their garden with others. They have hosted countless organized tours, including garden clubs, naturalist groups, master gardeners, botanical specialists and tourists from all over the world, including China, India, Korea, England, New Zealand, Sweden, Iceland, and Italy - and many of their flourishing experiments now grace others' gardens.