Squak Talk Blog

‘Sem’ Ash Leaf Spirea

Add multiple seasons of interest to your garden with a recent introduction that adds eye catching color and texture.  Sem Ash Leaf Spirea (Sorbaria sorbifolia ‘Sem’) is a compact growing, cold hardy (to –30 F) shrub.  Having recently gone through three winters that tested our gardens’ cold hardiness, we are always on the lookout for plants that can withstand snow, ice, and a deep freeze.  This durable, well-behaved plant should perform well in the garden or in a container, even if you live in our area’s colder spots, such as North Bend, Snoqualmie, or any of the high exposed hills on the Eastside.

In spring ‘Sem’ leafs out with pink to purple fern like foliage that matures to green tones.  This shrub, which matures around 3’ – 4’ tall and wide, shows off plumes of white flowers in summer.  In autumn ‘Sem’ turns bright red before the leaves drop adding yet another season of color and interest.  

Sorbaria ‘Sem’ grows best in full or partial sun conditions and likes moist, well-drained soil.  Consider pairing it with bold leafed companions such as Heuchera or Bergenia to provide textural contrast.  Plant a drift of purple, pink or lavender tulip bulbs this fall in front of your ‘Sem’ to provide an eye popping color show as each emerges next spring.  Come introduce yourself to ‘Sem’ today.


  1. Pam Nemzek

    I bought this shrub in 2009 because I thought it was so beautiful, and I still do. I am in zone 4a and it is in full sun.

    Last year I began to think that someone had put an incorrect label on the plant and I got sumac instead, because the thing is traveling underground and popping up all over about two feet away from the shrub. I just looked it up now. I really don’t want it to spread like crazy. Is this the nature of this SEM Ash Leaf Spirea? Thank you. Pam

  2. Squak Mt. staff

    Ash Leaf Spiraeas have been known to spread, however this specific variety, ‘Sem’ is reported to be well behaved. Because we have only 12 months of experience with Sem we cannot say with certainty that it will not spread, but have confidence it will not become a nuisance in the garden based on what we currently know. Keep us posted!

  3. jane

    Same here … my shrubs are 2 years old, and to my dismay this spring I’m also having the issue with them spreading underground and popping up elsewhere. (I actually dug up a couple of the small “freebies” and have transplanted them to an empty spot.) As pretty as they are I’m really hoping they don’t become an uncontrollable nuisance!

  4. Patty

    My compact well behaved Sem Ash leaf Spirea is spreading everywhere. Another plant to the recycling bin. Too bad—I liked the look of original plant. Need to change the labeling.

  5. Jeanne

    I too planted this and now 2 years later have additional
    bushes sprouted. I can’t afford to have it going to town if that’s what’s going to happen. Wondering about
    replacing it and putting it in a pot??

  6. Karen Kortuem

    Is there anything that can be done to keep this beautiful plant from sending shoots out everywhere? I like the plant, color, bloom and the area the original plant coves. Can’t deal with the suckers!

  7. brenda

    my sem ash leaf spirea leaves fall off every first of august every year but i was wonderingwhy that happens

  8. mattp

    You may want to try burying a large plastic pot (with the bottom removed) into the ground. Then plant the ‘Sem’ inside the perimeter of the pot. Alternatively cut the bottom out of a plastic garbage can and bury that in the ground. A similar strategy is often used for bamboo. Hope this helps!

  9. mattp

    Does it get any irrigation in summer? Perhaps drought stress is causing it to shed leaves. It should not be losing leaves until October…

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