Seed Zone Maps

Ecoregion Poster

We use seed zones to simplify the description of our seed collections and to aid our customers in purchasing the plants that are most appropriate for their project. Research based, species-specific seed zones don’t exist for most native species, but Level III Ecoregions, which are based on both biotic and abiotic factors, show promise as an approximate delimiter between populations under differing ecological conditions (for more details, see our article on the topic). We use Level III Ecoregions to describe the seed sources for most of the species that we propagate, although any plant that you purchase from us can be traced back to the original collection.

Tree Seed Zones

The biggest exception to our use of Level III Ecoregions is with our native trees.  Because of work published in 2002 by the USFS and WA State DNR, most of our native trees do have species-specific seed transfer zones.  These research based zones are better guidelines for seed transfer than Level III Ecoregions, and so we use them to describe our seed sources for the species for which they are available.  

Despite their usefulness, these seed zones can be a bit confusing. Unlike the old tree seed zones (developed in 1966), the new zone boundaries, zone names and numbers, and elevation bands are different for each species. The maps for species that we routinely grow are displayed below for your reference. If you have questions about these seed zones, please refer to the original publication located at:

 Abies grandis - Grand Fir Seed Zone Map

Abies grandis – Grand Fir

Alnus rubra - Red Alder Seed Zone Map

Alnus rubra – Red Alder

Chamaecyparis nootkatensis - Alaska Yellow Cedar Seed Zone Map

Chamaecyparis nootkatensis – Alaska Yellow Cedar

Picea sitchensis - Sitka Spruce Seed Zone Map

Picea sitchensis – Sitka Spruce

Pinus contorta - Shore Pine Seed Zone Map

Pinus contorta – Shore Pine

Pinus ponderosa - Ponderosa Pine Seed Zone Map

Pinus ponderosa – Ponderosa Pine

Populus trichocarpa - Black Cottonwood Seed Zone Map

Populus trichocarpa – Black Cottonwood

Pseudotsuga menziesii - Douglas Fir Seed Zone Map

Pseudotsuga menziesii – Douglas Fir

Thuja plicata - Western Red Cedar Seed Zone Map

Thuja plicata – Western Red Cedar

Tsuga heterophylla - Western Hemlock Seed Zone Map

Tsuga heterophylla – Western Hemlock

Old Seed Zone Map 1966

Old Seed Zone Map from 1966