Many excellent books have been written on gardening. Most of the authors of these books are from the eastern states, the South, or the West Coast. George Luxton's Flower Growing in the North, published in 1956, dealt only with flowers. When Gardening in the Upper Midwest appeared in 1978, it was the first comprehensive treatment of problems faced by gardeners in this region. The second edition places greater emphasis on fruits and vegetables.
The climate of Minnesota and surrounding states and Canada is different from that in other parts of the United States. In the winter, the temperature can drop to — 40°F. or colder. In the summer, temperatures can climb to 100°F. or higher. Not only does this area have extremes of temperature but it also has a fluctuating rainfall. Summer droughts are not uncommon. Generally, the rainfall decreases as one moves in a northwesterly direction. Average annual rainfall in our area ranges from about 28 inches in the southeast to about 16 inches in the northwest. Fortunately, most of this rainfall comes during the growing season.
The severity of our winters places the greatest limitation on the plants that can be grown. Winter injury on plants takes many forms:
Tip kill and dieback on woody plants may be the result of an early heavy freeze that occurs before plants have fully hardened, thus killing the late growth. Plants must be selected that mature earlier in the fall, and cultural practices must be modified to hasten this maturity.
Lack of flower bud hardiness is another problem with many kinds of plants. Peaches, flowering quince, and many azaleas cannot be grown successfully here because they lack flower bud hardiness. Breeding to develop hardier varieties offers the best solution to this problem.
Winter burn on evergreens is common. We have all seen yews and hemlocks turn red and brown in late winter. The plant hardiness laboratory in the Department of Horticultural Science at the University of Minnesota has shown that one cause of winter burn is a sudden drop in temperature. The sun, reflected from a white snow surface on a still day in February, may cause the temperature in the leaves to rise as much as 50° or 60° F. above the air temperature. If the sun goes behind a cloud or a building, the temperature drops suddenly and tissues within the leaves are killed. By planting sensitive varieties on sites where they will receive some winter shade, the problem of winter burn can be reduced. Another practical approach is to plant species and cultivars (see p. 9 for definition) that are naturally resistant to winter burn. The University of Minnesota Landscape Arboretum and Horticultural Research Center, both located on State Highway 5 west of Chanhassen, are evaluating thousands of species and cultivars of ornamental plants for winter hardiness and landscape qualities such as texture, foliage, color, bloom, and resistance to insects and diseases. We have identified a number of winter burn-resistance selections in evergreen species that typically show v/inter burn.
Sunscald on the southwest side of the trunk is still another type of winter injury that occurs on thin-barked trees especially during the first few years until they have developed a crown that shades the trunk. The Norway maples are particularly sensitive to this type of injury. Wrapping the trees in the fall with a tree wrap made of weather-resistant paper minimizes sunscald.
Soils are also highly variable, in both texture and pH. Heavy clay soils and sandy soils are intermixed in certain areas. In the same yard great differences in soil texture may exist. The gardener should understand the effect of soil texture on soil moisture and plant growth. Some plants do well on clay soils, others on sand. In northern parts of the area it would be unwise to attempt to grow apples on sand because of problems of winter injury. On heavier soils nearby, apples thrive.
The pH of the soil is another important consideration. Iron chlorosis, a yellowing of the foliage caused by a lack of available iron, can be a problem on alkaline soils, which are common in the Red River Valley and throughout the western parts of the region. Members of the rose family are extremely susceptible to iron chlorosis. Some plants, like ashes and lilacs, tolerate alkaline soils and these should be planted. Few soils in the region are extremely acid. Adding lime to such soils corrects any acidity problem.
If one recognizes the limitations, gardening in the North can be a rewarding experience. Some plants like peonies, lilacs, and flowering crabapples grow to perfection. We may never have a cherry blossom festival like that held in Washington, D.C. each spring, but we can have displays of flowering crabapples that are every bit as spectacular. In addition, we have the lovely fruits to attract birds to our yards during the winter. Fruit and vegetable growing can also be rewarding experiences.
This book is written to help new gardeners and those who may have moved here from a milder climate. It is also hoped that experienced gardeners may find information that will make them even better gardeners.
The book is organized to give gardeners a ready reference to the many gardening problems that arise. The first 6 chapters are devoted to a general discussion of plants and how they grow and to cultural practices like soil management, pests and their control, and the pruning and training of plants. Chapters 7 and 8 cover the growing of fruits and vegetables in the home garden. The rest of the book is devoted to the aesthetics of gardening, including landscape design, the lawn, and the selection of ornamental plants. Lists are included to help gardeners select the right plants to make their yards more beautiful and useful. (Plants are listed alphabetically by scientific names, with common names in parentheses.) There are chapters on the selection and care of deciduous trees, deciduous shrubs, evergreens, vines, ground covers, perennial and annual flowers, bulbs, and garden roses. Ferns are included in Chapter 17. A hardiness zone map, keyed to the individual plants, is provided in Chapter 11, p. 112.
The information in this book is based on my experience as a gardener, my teaching and administrative experience at the University of Minnesota as head of the Horticultural Science and Landscape Architecture Department,Superintendent of the Horticultural Research Center, and director of the University of Minnesota Landscape Arboretum. I have also answered thousands of gardening questions in my weekly gardening column in the Minneapolis Star and Tribune and on my monthly gardening program on WCCO radio.
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