Save a Forest in Southworth, WA

Southworth Forest Update:

Western Hemlock Transplants Prove Tricky But Manageable

Posted September 23, 2023 by Southworth Forest

These young Western hemlocks were transplanted into pots from a Vashon Island location in November 2022 and will be planted in the Southworth forest in November 2023. Once there, 40% typically survive their first few years with summertime watering. (2023)

Much has been written about the gloomy future for Washington State's official tree, the Western hemlock. Aphid-like insects and drier conditions are moving north to threaten this tree's place in the Puget Sound region and beyond. It remains a majestic tree, however, and one that typically grows under fir trees as a replacement generation.

There are surprisingly few young Western hemlocks thriving in the Southworth area of Port Orchard, WA. In the few remaining natural forests of the area, they have yet to establish themselves under the fir and cedar trees that dominated after the mass harvesting of the area 50 to 60 years ago. They still have an important role to play, however, as one of the most shade-tolerant native trees available.

At the 2022-2023 King Conservation District plant sale, the Western hemlock was the only species of ten trees offered that did not sell out. (It was not offered at all at the Kitsap Conservation District sale the same year.) They can be really fussy to transplant in the wild as well. Unless you move them (into pots or directly to another location) in November or December, you risk losing them the following summer even with consistent watering.

Because hemlocks have a shallow root system, they tend to require wider holes or pots to maximize their chances for survival when transplanted. Creating a compost-rich dirt bowl free of noxious weed remnants like Scotch Broom and English Holly will help. Hemlocks also prefer to be consistently wet, requiring regular watering in summers during their first three years. (Volunteer trees left where they sprout in shade are a little hardier in this respect.)

For the Southworth forest, about 150 young hemlocks were sourced from locations slated for clearing on Vashon Island. Roughly half of them survived the initial potting. Once planted at Southworth, they have a survival rate of 40%. They especially struggle in areas exposed to dry heat at a young age, and several of those planted near the neighboring deforestation violation at 11090 SE Southworth Dr. did not survive their first summer.

With proper soil amendment, consistent weekly watering in summers, and positioning in partial shade, Western hemlocks can still thrive in the Puget Sound region. Even though the majority of them may perish in the first three years after transplanting, those that do survive this period of adjustment tend to flourish and grow faster than many of their fir, spruce, and cedar counterparts.

A dead hemlock is shown with the Edwards deforestation violation in the background. When hemlocks die, their demise can come very suddenly. The tree can look healthy one month, with ample new growth, and be completely dead from top to bottom the next. Partial dieback is not always fatal, however. (2023)