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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

MAILING ADDRESS: 1120 SW 5th Ave, Room 1000, Portland, OR 97204

More Contact Info

What is being done about it?

The City of Portland has completed its garlic mustard work for 2018.  Now that seedpods are dry, plants should be left in place:  it's easier to remember where we've left plants than to risk scattering seed in transit!

(last updated: 7/12/18 MRB)

Areas treated by Environmental Services so far include:

Areas managed in 2018 Treated on
Springville Rd (E) and Linnton 4/21/18
SW Multnomah & 45th 4/22/18
NW Skyline (Cornell-Germantown) & NW Thompson 4/23/18
NW Cornell (Miller-Westover) 4/24/18
NW Greenleaf, NW Royal, NW Skyline (Cornell-Barnes), W Burnside (Barnes-25th) 4/25/18
NW Fairfax, NW Albemarle, NW Hermosa 4/26/18
Hwy 26, SW 61st, SW Salmon [handpull] 4/27/18
SW Humphrey/SW Fairmount 5/2/18
SW Lesser/Pasadena/Taylors Ferry/45th 5/3/18
SW Boones Ferry/Taylors Ferry/Macadam & Oaks Bluff 5/7/18
NW 53rd/Germantown/Saltzman (E) & SW Hewett 5/8/18
NW Saltzman Rd. 5/10/18
SW Terwilliger/Patton/Dosch/Hamilton 5/11/18
SW Maplecrest/Ridgeview/Lancaster 5/14/18
Rocky Butte 5/15/18
N Portland Rd. 5/16/18
SW Slavin Rd/Sam Jackson/Cardinell 5/17/18
Beaverton-Hillsdale & Fanno Creek 5/21/18
Beaverton-Hillsdale & Fanno Creek (II) 5/22/18
SE Flavel/Foster/Barbara Welch [handpull] 5/25/18
NW Skyline/Cornell review [handpull] 5/31/18
Beaverton-Hillsdale & Fanno Creek (III) [handpull] 6/4/18
SW Fairmount review [handpull] 6/12/18
SW Greenhills review [handpull] 6/19/18
locations in bold were treated in the last 14 days  


Current Phase (in bold)

Description of Garlic Mustard In Each Phase



Like many plants, garlic mustard changes form several times over its lifetime. A typical garlic mustard plant forms as a seedling in the spring and overwinters as a rosette: a low-growing cluster of leaves typically one to six inches tall. The rosette form is easily confused with several native species, and is often hard to find under winter's leaf litter.




With longer, warmer days in March and April, garlic mustard rosettes undergo a change called bolting. The stems lengthen and leaves go from round to triangular.  Buds form at the top of the rising cluster of leaves.




After a sufficient number of warm, light days in April or May, the buds atop bolting plants will open into garlic mustard's characteristic four-petaled white flowers. The flowering stage of garlic mustard typically lasts three to four weeks. Herbicide treatment is most effective during this phase. Roots not removed during pulling will likely form a new flowering plant in a few weeks.


Seeds Forming


Seed formation occurs over the course of two to three weeks. Many plants will display flowers at one end of the bud cluster and new seed pods at the other end. By the time all flowers have formed seeds, it is typically late May or early June in the Portland area. Careful herbicide treatment can halt seed maturation in this phase. Pulling efforts should still attempt to remove all roots. All pulled plants should be bagged and disposed of in the trash to prevent spread in yard debris.


Seeds Ripening


Mature seeds ripen for four to six weeks until the plants begin to dry out, typically in early to mid-July. Pulling can be done in this phase, without regard for root re-growth, but MUST stop when plants begin drying. Herbicide treatment will have no effect during this phase and should not be attempted.


Seeds Ripe Don't pull!


Newly-dry seedpods will explode at the slightest touch, depositing seeds in clothes and hair and making the well-meaning puller an ideal vector for infesting new areas.