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Courtyard Garden
Planted in 1985, the original Arboretum garden contains native and exotic
plant species suitable for high elevation gardening. At 7,150 feet above sea
level, species must be able to withstand extreme environmental conditions
including 110 inches of snow annually, a 75-day growing period, wide daily
temperature fluctuations, spring drought, drying winds, and soils that won’t
hold a lot of needed moisture.
T he Courtyard Garden
displays a method of watering that is consistent with the ideas of
ecological horticulture which is based on natural plant habitats. In the
ecological landscape, you can create a zoned landscape by recognizing
microclimates (cold and warm spots) on your site and choosing native plants that
naturally thrive in similar zones and habitats. For example, plants in this
garden receive excess water from rainfall through a drainage that runs from the
roof to the garden. This method of watering cuts back on manual labor and takes
greater advantage of nature’s watering system.
O ne plant that benefits
from roof runoff is the rare Chiricahua dock (Rumex orthoneurus),
native to the mountains of southeast Arizona. It is a perennial that prefers a
habitat of moist organic soils near streams and springs. This relative of the
prolific midwestern weed thrives in cultivation, but in the wild is threatened
by cattle grazing, recreation, mining, and road construction. Protected within
The Arboretum’s 12-foot-high elk fence, this species produces thousands of
seeds when allowed to flower, in the protected environment of the garden.
A lso found growing in this
garden is the Arizona willow, another rare species that benefits from
ecological watering methods. Threatened by habitat degradation, as well as
cattle, elk, and insect herbivory (animals that feed on plants), the native
willow grows only in Arizona and Utah near perennial streams and meadows at high
elevations. Runoff from the roof feeds the drainage and provides supplemental
moisture that might otherwise be lost to the plant.
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