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Where to plant and grow white pines

Site selection
White pine can and does grow in all parts of Minnesota. White pine blister rust hazard zones (see map) indicate the general level of hazard over broad geographic areas but should not be used to determine hazard on a specific site. White pine can be grown successfully in all hazard zones, but as hazard increases, it becomes more important to carefully select planting sites (soils, topography, shade) and to implement pest management strategies (see Tending Your White Pines section).

Soil types
White pine occurs naturally on a wide range of soil types and textures. Good growth occurs on most soil textures and soil drainage classes. It is more tolerant of wetter conditions than red or jack pine but is less tolerant of droughty conditions. Best growth will occur on sites with: medium to fine soil texture, medium to high soil fertility, somewhat poor to well drained soil, constant moisture supply and rooting zone greater than 18 inches deep. Avoid the extremes of heavy, continually wet soils and coarse, drought-prone soils when selecting a planting site.

Topography
Plant white pines on steep slopes, hill tops and shoulders of hills. Avoid V-shaped valleys, potholes, bases of slopes and small openings in the forest canopy anywhere in Minnesota. A small opening is one where the spaces between the crowns are 1/4 to one times the height of the surrounding trees. These features favor the collection of cool, moist air and favor infection by the white pine blister rust fungus in both northern and southern Minnesota.

Shade
White pine grows better and has better form if growing under the shade of other trees. Unlike red pine or jack pine, white pine can easily tolerate growing under an overstory. Planting under an overstory has two benefits, namely, reduced risk of white pine blister rust infection and reduced risk of white pine weevil attack.

Aspen, birch, oak and other hardwoods are good choices for the overstory. Tree species that are intermediate or shade intolerant, such as, aspen and birch, have smaller, thinner crowns that allow light to penetrate to the understory. Shade tolerant species, such as, sugar maple and basswood, have large, dense crowns that intercept lots of light and are likely to significantly reduce the growth of the understory white pines.

High shade (from overstory trees that are significantly taller than the white pines) is preferred to shade from brush and shorter trees that are similar in height to the white pines. High shade is beneficial; less incidence of blister rust and better growth.

Look for and choose the sites: where aspen (or birch) is mature and the stand is breaking up, where a hardwood stand just underwent thinning or where a stand was partially harvested. The overstory should be vigorous enough to survive an additional twenty to thirty years. Heavy or continuous shade can be detrimental to white pine growth, so, as a goal, maintain approximately 40 to 60 percent shade. You can tell if you're on the right track with the correct amount of shading if the white pine seedlings grow about 1 to 1 ½ feet in height per year after being established for six to eight years.

Shade or no shade. Planting white pine seedlings in the open (like in an old field) is more acceptable in Hazard Zones 1 and 2 because the climate is less favorable to white pine blister rust infection. In Zone 2, blister rust can be a problem so avoid open field planting in V-shaped valleys, potholes and the bases of slopes.