Common bad guys
By Bonnie Orr
WSU Chelan/Douglas County Master Gardener
These three weeds are common bad guys:
Common purslane (Portulaca oleracea) can produce 240,000 seeds per plant and the seeds can stay viable for up to 40 years. It mostly grows at the edges of the lawn, in sidewalk cracks, next to a driveway. One way to contain it is to alter your watering patterns so bare soil is not watered. Seeds can continue to ripen after the plants have been pulled. Any part of the plant can resprout. The seeds sprout when the soil temperature is near 70 degrees and the air temperature 70-80 degrees. Three inches of mulch will prevent the seeds from germinating. Pre-emergent chemicals are effective if applied before the seeds sprout.
Spotted spurge/prostrate spurge (Euphorbia maculata) seeds germinate when the soil temperature is 60 degrees and the air temperature 75-85 degrees. It can regerminate throughout the summer in weak areas of turf.
Oxalis or woodsorrel ( Oxalis stricta) germinates when the soil is about 50. When ripe, the seeds can be cast up to 16 feet away from the parent plant. Oxalis is a perennial and grows from underground stems or roots. This plant is controlled with specific, broad-leaf herbicides.