Home & Garden

Spot invasive weeds early, then remove them

Common purslane is common on the Central Coast.
Common purslane is common on the Central Coast.

An invasive weed is an unwanted plant (native or non-native) that is able to establish on many sites and grow quickly to the point of disrupting the well-being of valued plants in the same location. For most home gardeners, weeds are unwanted — period. In order to keep them out of the garden, there are a few management practices that can be put into place to keep weeds under control: identification, eradication and prevention.

A key factor in fighting the good fight against invasive weeds is to be able to identify them. We all know what’s supposed to be in our gardens so when something pops up that wasn’t put there on purpose, we wonder “what the heck is that?”

A few invasive weeds common to the Central Coast are:

  • Black Mustard (Brassica nigra)
  • Purslane (Portulaca oleracea)
  • Cheese weed or mallow (Malva neglecta)
  • Russian thistle (Salsola iberica Sennen)
  • Filaree (Erodium cicutarium)
  • Sow thistle (Sonchus oleraceus)
  • Goat head or puncturevine (Tribulus terrestris) Vetch (Vicia)
  • Mare’s tail or Horsetail (Conyza canadens)
  • Yellow star thistle (Centaurea solstitialis)

Eradication of invasive weeds includes manual and chemical methods. If weed chemical warfare is not part of your eradication arsenal, hand-pulling the invasive beasties, roots and all, is the most effective and efficient approach. The goal is to detect and pull out the invasive weed before it reproduces and spreads. There’s nothing worse than having vetch get away from you — one minute it’s a two-inch weed and the next it’s three feet long covering everything in its path.

The best form of prevention is early detection. Being aware of common invasive weed species can only help a gardener formulate a better plan of attack against them. If total prevention is the goal, consideration may be given to using mulch or weed cloth in bare garden areas to deter weeds from moving in. Only watering where there are wanted plants can also help deter invasive weeds from growing.

To guard against invasive weeds moving in to your garden, know the common species, eradicate them before they reproduce, and have a prevention plan in place. Visit the UC IPM Weed Gallery for photos and more information — www.ipm.ucdavis.edu/PMG/weeds_intro.html.

Jackie Woods is a UC Master Gardener.

Got a gardening question?

In San Luis Obispo call 781-5939, Arroyo Grande, 473-7190 and Templeton, 434-4105. Visit us at http://ucanr.org/sites/mgslo/ or email us at anrmgslo@ucanr.edu. Follow us on Instagram at slo_mgs and like us on Facebook. Informative garden workshops are held the third Saturday of every month, 10 a.m. to noon at 2156 Sierra Way, San Luis Obispo. Garden docents are available after the workshop until 1 p.m. To request a tour of the garden, call 781-5939.

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