Skip to Main Content View Text-Only

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

More Contact Info

What is being done about it?

The City of Portland hires licensed contractors to survey and treat garlic mustard plants along roads and stream corridors in Portland during the spring and summer.  Spray treatments have stopped, however, since seeds are now ripe in their pods.  Because the pods are likely to dry out very quickly in the unusual heat, we also strongly suggest that handpulling stop as well.  From now on, handpulling substantially increases the risk of inadvertent seed spread.  In general, the City of Portland's work on garlic mustard has finished up for 2015.     

(last updated: 6/25/15 MRB)

Areas treated by Environmental Services so far include:


Areas managed in 2015 Treated on
SE Thorburn 4/9/2015
Linnton + Springville Rd. neighborhood 4/15/2014
SW Barbur 4/16/2015
SW Taylors Ferry/35th/Huber 4/16/2015
SW Capitol Hwy & Lesser 4/16/2015
SW Pasadena (55th-59th) 4/16/2015
NW Skyline (Cornell-Germantown) 4/17/2015
NW Cornell (Miller-Westover) 4/20/2015
NW Greenleaf (Skyline-Cornell) 4/20/2015
NW Skyline (Royal-Cornell) 4/20/2015
SW Multnomah 4/21/2015
SW 45th/48th 4/21 & 4/22/2015
SW Vermont (55th-Shattuck) 4/22/2015
N Portland Rd. 4/22/2015
W Burnside 4/23/2015
Hwy 26 (Sylvan & Zoo exits) 4/27/2015
Fairmount Loop and connecting streets 4/27/2015
SW Humphrey 4/27/2015
SW Patton (Dosch-Scholls Ferry) 4/27/2015
SW Hamilton (Dosch-Scholls Ferry) 4/27/2015
SW Dosch (Patton-Hamilton) 4/27/2015
NW Germantown Rd. 4/29/2015
NW 53rd Ave. 4/29/2015
NW Royal Blvd. 4/29/2015
NW Scholls Ferry Rd. 4/30/2015
NW Shattuck 4/30/2015
NW Scholls Ferry 5/1/2015
SW Maplecrest @ Marshall Park 5/1/2015
SW Palatine/Taylors Ferry/Macadam 5/2/2015
SW Boones Ferry (Terwilliger-county line) 5/2/2015
SW Beaverton-Hillsdale Highway & Fanno Creek (Bertha-65th) 5/4/2015
SW Hewett/Ormandy/Greenleaf 5/4/2015
SE Flavel/122nd 5/7/2015
SW Lancaster/Terwilliger/Capitol Hill 5/8/2015
SW Sherwood/Montgomery/Upper 5/14/2015
NW Miller/Skyline/Burnside 5/15/2015
NW MacLeay & neighborhood 5/18/2015
N Going/SW 41st 5/19/2015
Rocky Butte/Council Crest followup 5/20/2015
SW Market/Vista 5/21/2015
SE Clatsop/Deardorff 5/22/2015
SE Barbara Welch/Foster [pull] 5/29/2015
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.