Ornamental Trees
Subjecting plants to standing water helps select varieties that can better tolerate poorly drained soils. Researchers put trees through many survival tests before they're made available to the nursery trade and propagated for consumers. Minnesota has a thriving horticultural industry, with annual sales of more than one billion dollars.
PROPER PLANTING IS CRITICAL if you want healthy, vigorous trees and shrubs. Start with a hole at least twice as wide as the rootball. If you're planting a tree or shrub with a main trunk, gently brush soil away from the stem to find the first root closest to the soil surface. This area is the 'root flare,' the transition zone between a tree's trunk and roots.
When a tree or shrub is planted too deeply, the roots may partially or completely encircle the trunk above the root flare and interrupt the flow of sap to the roots. Eventually, the flow stops and the tree dies. This condition — known as girdling root syndrome — may also cause the tree to fall in a windstorm, as U of M researchers documented in the severe storms of 1998.
Adjust the soil depth in the planting hole so the first root will be just below the soil surface. When you fill the hole you may add compost, peat or composted woodchips to replace up to one-third of the original soil volume. For proper drainage, it is vital that the soil you use for backfill consists mostly of original soil.
Water regularly during the first few growing seasons until the plant is well established. The type of soil (clay, sand, etc.) will determine how much water is needed.
Red Maple, Acer rubrum
Autumn Spire* 1992 upright form, good red fall color, 40'
Northwood* 1980 hardy, bright orange fall color, 50'
Buckeye, Aesculus
Autumn Splendor* 1980 dark red fall color, resists leaf spot diseases, shiny nut-like fruits
Flowering Plum OR Almond, Prunus
Princess Kay* 1986 10-15 feet, usually no fruit, attractive trunk and branches
Manitou 1923
Newport 1923
Redbud, Cercis canadensis
Minnesota Strain* 1992 hardy, early spring flowers
Corktree, Phellodendron amurense
His Majesty* 1996 fast growing, open-spreading, male selection producing
Kentucky Coffeetree, Gymnocladus dioicus
Stately Manor* 2002 male selection, no seed pods, easy to grow grass under this tree
Crabapple, Malus
Sparkler 1969
Vanguard 1963
Radiant 1958
Flame 1934
*=varieties available from retail nurseries, those without are heirloom varieties with limited availability
Continue on to 150 Years of Shrubs
'Northwood,' as its name indicates, is a maple that does well in the northeastern areas of Minnesota. Known for rapid growth, it is a round or oval tree that matures to about 50 feet high. It prefers moist, acidic soils.
'Autumn Splendor' buckeye is grown for its glossy green foliage and burgundy fall color. At maturity it reaches 35 feet, with an upright-oval form. It produces large yellow flowers and a fruit similar to the horse chestnut.
'Princess Kay' is a showy, double-flowered selection of Canadian wild plum (Prunus nigra) found growing wild in Itasca County, Minnesota. Its fragrant flowers last from seven to 10 days in late April or early May. Very attractive for northern landscapes, it must have well drained soil.
'Minnesota Strain' redbud displays an attractive dark pink to purple flower in early May. Growing to 12 feet, the small trees are open-spreading with multi-stems and are suitable for protected sites in southern Minnesota.
'Sparkler' crabapple's rose-pink flowers are a spring highlight. Newer varities are more disease resistant, but this spreading tree still yields deep red fruits and winter food for birds.
