Tsuga mertsiana, or mertensiana, is the scientific name for a coniferous tree commonly known as the mountain hemlock. It is grown mainly in the lower-elevation as well as sub-alpine forests in British Columbia, also in Washington, Oregon, Alaska, and California. The mountain hemlock can be recognized by the way its top tips to one side. This is a slow-growing evergreen tree, which thrives in very moist soil and needs long winters and short, cool summers. The soil in which you plant your tsuga mertensiana should be loose, coarse-textured and somewhat acidic (a pH of 3.4 to 5.0).
Choose a shady to partially sunny location in your garden for the mountain hemlock tree. Remember, although it is slow-growing, it can grow to be quite large.
Spread a 3-inch layer of pine bark or cedar mulch over the soil and allow it to sit over the winter.
Dig up the planting area to a depth of one foot, turning the soil and crushing any large clumps of soil.
Add a 4-inch layer of sphagnum peat moss and a 2-inch layer of compost. Mix this in well with the soil.
Dig a hole twice the width of the pot in which the mountain hemlock is currently growing, and the same depth. Gently remove the sapling from the pot and place it in the hole. Backfill the hole, tamping the soil as you go to remove any air pockets.
Water the soil well, allow it to drain, and water again.