Issue 7, June 10, 2013

Common Purslane -- Blessing or Bane?

I've always found common purslane (Portulaca oleracea) to be an interesting plant.  Some will curse its appearance in their garden and others will embrace it.  Again, we are reminded that a weed is only a weed if it is unwanted where it is growing.  The primary redeeming quality to purslane is that it is edible.  Ironically, one weed book I have calls it a "good weed."

Common purslane is typically a late-germinating summer annual broadleaf weed. However, I have had reports of it germinating already this year. The stems are succulent (juicy if you will), smooth, often reddish, and prostrate. They can reach to approximately 24 inches in length and form a prostrate mat.  The leaves are thick, fleshy, shiny, and smooth. They are alternate to nearly opposite, rounded at the tip and narrowed at the base, and up to 1¼ in. long. They are often clustered near the ends of branches. Overall, this plant is very reminiscent of a jade plant.

The flowers are yellow with 5 petals, borne individually in the leaf axils or clustered at the ends of branches. They appear July through September. The fruit is a globular capsule that splits at the middle. 

This weed is extremely common in cultivated areas, such as gardens, bare-soil areas in landscape beds, and cultivated nursery fields.  It thrives in sunny, fertile, sandy soils but will tolerate poor, compacted soils.  Common purslane is extremely drought resistant; in fact it thrives in hot dry conditions.  After last year's drought, we are likely to see an increase in populations of it this year.  It is almost impossible to control through cultivation alone.  Actually, cultivation will propagate (multiply) this plant.  Before you till your garden, be sure to check for the presence of this weed.  Timely proper identification is important.

The root system consists of a long taproot with fibrous lateral roots.  It is fairly shallow, so hand pulling is fairly easy.  Cutting with a hoe at the base of the plant is also effective.  There is one note of importance here: Stems will root wherever so don't leave plant fragments lying after weeding or you will be weeding again shortly.  An older client told me once of how her mother would send her out to weed with two collection bags – one was for the "fat" weeds -- purslane.

Common purslane grows well in sunny spots and tight crevices.  Years ago, I was hired to do some weeding for a home gardener.  I was fresh out of college and armed with the knowledge that this species was indeed a weed.  Low and behold she had a lot of it growing in between the pavers of her patio.  I was surprised to be told that she was encouraging it to grow there and that I should leave the area alone.  The site was perfect for growing it.  Why fight it?  She planned to eat it instead.  Brilliant!  The leaves can be eaten cooked or raw and they are reportedly rich in omega-3 fatty acids and beta-carotene as well as high in magnesium, potassium and some other nutrients.  They have a slightly sour taste and are considered to be a delicacy in certain parts of the world.   

On the other hand if you are not interested in having a population of common purslane in your garden, landscape or lawn, prevention is a good tactic.  Remove or kill plants before they produce seed. In a landscape bed, mulch can be effective.  In a vegetable garden, newspapers, black plastic and grass clippings are a few "ground covers" that can be used to prevent seed germination.  For lawns, raise the mowing height if practical to shade out this weed.  Adjust your cultural practices in order to encourage better growth of the turf and to make it more competitive.

Several herbicides are labeled for controlling common purslane.  Preemerence herbicides could still be applied if emergence has not occurred.  If plants are up and ready to take over your location, you can use a postemergent herbicide.  For lawns, these herbicides can be used: dicamba, dithiopyr, pendimethalin, prodiamine.  For vegetable gardens, trifluralin or napropamide may be tried.  In landscape beds, pendimethalin, oryzalin, and trifluralin will provide effective control.  Additionally, spot applications of glyphosate can be effective.  Other herbicides may be used as long as the label allows it and includes common purslane in the list of target pests.  Be sure to carefully read and follow all pesticide label directions. (Michelle Wiesbrook)

Michelle Wiesbrook

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