University of Washington Botanic Gardens

Root wad of fallen red oak in west lagoon

Two leaning mature red oaks (Quercus rubra) fell last week in the arboretum. The one that went down at the north end of Azalea Way, near our famous propped Willow oak, was witnessed by several onlookers as our arborist Chris Watson was hurredly trying to stablize it from going over. He never had a chance. The popping and cracking noises from severing roots on the backside kept getting louder and more frequent. It was sad and awesome at the same time. Not many people get to see a large tree go down on its own volition.  The other oak is located at the water’s edge in the west lagoon area. This oak was significant from a curation standpoint too.  It was wild-collected in the Adirondacks in 1958 by the Morton arboretum. Arboretum staff hope to keep its massive root wad (see photo) intact for interpretive and educational opportunities.  Both oaks were leaning and growing in shallow soils, had insufficient support roots, extraordinary spring growth and wet, heavy foliage when they failed. The fact that there were two trees of the same species topple  at approximately the same time was indeed a rare coincidence in the arboretum.

The UWBG horticultural crew will be making renovations to the southeast bed, which will include removing, relocating, or protecting other UW plant collections in the project area, followed by regrading of the bed and soil remediation. The 2009-2010 fall and winter planting of new winter-interest trees, shrubs, and ground covers will also take place.

This project will reclaim over 5,000 sq. ft. of bed space that is now detrimentally shaded by elm trees. It will also renew UW Landscape Architecture Professor Iain Robertson’s original 1987 Winter Garden design intent.

This renovation was made possible by a gift from the Arboretum Foundation, which was given to them from Lake Washington Garden Club, Unit 3.

Renovation information sheet.