Spiraea splendens var. splendens

                   (syn. Spiraea densiflora)


Subalpine spirea, rose meadowsweet


  photo of Spiraea densiflora  

  Photos: © Mike Tyler Jr, © 1999 Thayne Tuason and Derrick Ditchburn



Found in British Columbia, south to northwestern California and the Sierra Nevada Mountains. It extends eastward to Montana, Idaho, and eastern Oregon. (1)


Climate, elevation

600 to 3050 m (1,4)


Local occurrence

Found throughout the Olympic and Cascade Mountains in Washington. (1,2)


Washington County Distributional Map for Spiraea splendens var. splendens


Habitat preferences

Grows at edges of streams and lakes, in montane meadows, gaps in the forest, wooded and rocky slopes and in open subalpine forests. It prefers to grow in moist soils, in full sun to light shade. (1,4)


Plant strategy type/successional stage

Mid-seral to climax


Associated species

Found in the Tsuga mertensiana - Xerophyllum tenax association, which includes mountain huckleberry (Vaccinium membranaceum), pipsissewa (Chimaphila umbellata), grouseberry (Vaccinium scoparium), Geyer’s sedge (Carex geyeri), coiled lousewort (Pedicularis contorta) and pink wintergreen (Pyrola asarifolia) (6)


Also associated with western hemlock (Tsuga heterophylla), marsh marigold (Caltha biflora), sitka alder (Alnus sinuata), subalpine fir (Abies lasiocarpa), white-flowered rhododendron (Rhododendron albiflorum), and Pacific silver fir (Abies amabilis). (7)


May be collected as:

Softwood cuttings, hardwood cuttings, seed, rhizomatous offshoots, layered cuttings. (5)


Collection restrictions or guidelines

Collect seeds when follicles are dry and begin to open in fall, cutting capsules into paper bags for collection.  Seeds should be light tan when they have reached maturity.  Seed should remain in a well-ventilated dry area while awaiting cleaning and sowing. (3)


Seed germination

Recommended 48 to 75 day cold-moist stratification.  Roll seeds in moist paper towels and store in open plastic bags in 3°C refrigeration. (3)


Seed life

Seed longevity is unknown. (3)


Recommended seed storage conditions

Seeds should be kept in cool, well-ventilated storage area.


Propagation recommendations

Softwood cuttings:  Collect one-year-old softwood cuttings into plastic bags in early summer and kept refrigerated until processing.  Cuttings should be 15-20 cm long and roughly 8 mm caliper.  Larger cuttings may be directly planted into 1 gallon containers.  Rooting may be aided by application of 5000 ppm liquid IBA (indole butyric acid). (3)


Seeds:  Seeds should be sown shallowly or on surface of medium, as they require light for germination. (3)


Soil or medium requirements

Cuttings should be grown in mistbed in 50% perlite and 50% sand with bottom heat (12 cm below medium) kept at 21°C.  Outdoor mistbeds should remain covered with shadecloth throughout rooting phase. (3)


Seeds are successfully grown in a mix containing:

-70% 6:1:1 milled sphagnum peat, perlite, and vermiculite

-30% sand with slow release fertilizer (3)


Installation form

Usually outplanted as a container plant with high establishment success.  Fibrous rootballs of container stock must be well loosened or scored before outplanting. (3)


Recommended planting density

Space plants 18-36 inches apart.


Care requirements after installed

Newly planted individuals must be watered regularly during establishment; soil should not dry completely between waterings. (3)


Normal rate of growth or spread

Plants grow very rapidly following establishment. (3)


Sources cited

1.  Rose, R., C.E.C. Chachulski and D.L. Haase.  1998.  Propagation of Pacific Northwest Native Plants.  Corvallis, OR: Oregon State University Press. 


2.  PLANTS Database.  United States Department of Agriculture. http://plants.usda.gov/java/profile?symbol=SPSPS. Accessed 27 May 2006.


3.  Native Plant Network.  Native Plants Propagation Protocol Database. http://nativeplants.for.uidaho.edu/network/ Accessed 27 May 2006.


4.  Hitchcock, C.L. and A. Cronquist.  1973.  Flora of the Pacific Northwest. Seattle, WA: University of Washington Press.


5. Dave’s Garden.  http://davesgarden.com/pf/go/75346/.  Accessed 22 May 2006.


6. Forest Vegetation of Eastern Washington and Northern Idaho. 1984. Pullman, WA: Washington State University.


7. Spiraea densiflora. WTU Herbarium Image Collection. Burke Museum. http://biology.burke.washington.edu/herbarium/imagecollection.php. Accessed 1 Jun 2006.


Data compiled by

Alaine Sommargren, 1 June 2006