Mountain Hemlock

Tsuga mertensiana

Easily one of my top 5 trees for the Pacific Northwest garden, this graceful conifer can work in *almost* any landscape adding structure and interest through out the entire year. It is native to sub alpine and high elevations in the mountain ranges from Alaska down to through Oregon.  In its native habitat, it can grow over 100′ tall but stays relatively narrow for a conifer of that size.

In their glory at Steven's Pass WA

In a garden setting you can expect a Mountain Hemlock to grow 6-12″ per year in good conditions becoming 10-12′ in ten years but only 4-6′ wide. They can add an alpine flair to the garden and look great growing in small groups.  They grow well in full sun to partial shade (not as shade tolerant as other Hemlocks) and thrive in sheltered locations with well drained soils.  Compared to its buddy the Subalpine Fir Abies lasiocarpa, it is more adaptable to lowland regions and relatively disease and pest free.
This high altitude species is usually harvested directly from the mountains and brought into the nursery trade through harvesters around May-June as the snow pack starts to melt.   As they are getting established in your garden it is extremely important to monitor moisture levels in the soil and make sure it stays moist, especially during the first summer.  NOTE: “Moist” should not be confused with “saturated”. It is not uncommon for these trees to die in the first year from the shock of being transplanted and from not being cared for correctly.  After the first couple of summers Mountain Hemlocks are virtually maintenance free and drought tolerant.

This trio resides in my own garden

There are more and more nursery grown Tsuga mertensianas becoming available to gardeners, even new cultivars being grown for their blueish foliage called ‘Blue Star’ and ‘Glauca’.  When shopping for these trees be sure to ask when they were brought in and if they were harvested or nursery grown.

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