SUCCESSFUL PLANTING 
WITH 
REALLY HARDY PLANTS 
W. T. COWPERTH WAITE 
Landscape Architect, Minnesota 
What Will Endure the Hot Summer and Extreme Cold of the North 
Central Region Where the Outdoor Garden Season is of Short Dura- 
tion? — Local Lessons in Hardiness that can be Applied Generally 
B DIFFERENCES and extremes of rain fall and tempera- 
I ture are prime factors in deciding the adaptability of 
| particular plant material to a given section. This is 
2 of course perfectly obvious to anyone, and it is a natural 
deduction that those plants which can endure the most trying 
conditions are also the reliable material for gardens in general 
or for people who want easy results. 
Within the tributaries of the upper Mississippi and eastern 
Missouri river system (which includes large sections of northern 
Iowa, Wisconsin, Minnesota, and the eastern part of the two 
Dakotas) exists a territory where many plants are put to the 
supreme test. Certain conditions of soil, temperature, and rain- 
fall divide this region from other sections in sister states. These 
differences of climate are, of course, but gradual changes with 
considerable variation even within the section. A considera- 
tion of the range of rainfall and of temperature in the North 
Central states will at once make apparent one reason for the 
gardening peculiarity of the region. In Minnesota the average 
annual precipitation is roughly about 24"; for northern Iowa,. 
30"; for North Dakota, 20"; and for Wisconsin 30". Compare 
these averages with the 48" average for Rhode Island; the 40" 
average for Missouri and the 41" average estimated for the 
section about Philadelphia! 
A comparison of the mean average of temperatures is likewise 
enlightening. At Des Moines, Iowa, an average temperature 
of 40° has been estimated while 43 0 is given for Wisconsin, with 
about 37 0 for Minnesota. The same authority gives 52 0 for 
Philadelphia and 53 0 for the state of Indiana. These are 
marked differences but alone do not tell the story of the great 
range of temperatures in the North Central areas, a character- 
istic that is most decisive in determining plant hardiness. 
Thirty and even forty degrees below zero is not unknown in St. 
Paul, Minn., although it is hardly a yearly expectation, and hot 
summer days may occasionally register close to ioo°. This 
means a range of temperature of some 125 0 from coldest winter 
to warmest summer. Then the transition from winter to spring 
A SUCCESSFUL BIT OF NORTH CENTRAL REGION PLANTING 
That might well be duplicated elsewhere. Nasturtium draping down from above, and Engelmann's Creeper climbing up 
from below, between them pretty well occupy the surface of the retaining wall, whose base is quite hidden by a border of 
Phlox, Iris, and other hardy plants. (For full planting scheme of these grounds see illustration on following page) 
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