It's been a while since I've posted information pertaining to southern California gardeners.  From the Long Beach Press Telegram, here is a short article on how to control Nutsedge using organic methods.

  Horticulturist Jill Morganelli avoids spraying weed killer in the foundation gardens she manages at the Los Angeles County Arboretum and Botanic Garden in Arcadia. Not even when they’re overrun by nutsedge, an invasive grasslike weed.

  In her opinion, reaching for the spray is no more effective than her nonchemical techniques of weeding, soil building and flaming the area, as well as learning all she can about the weed.

  “You’re not going to eradicate it,” says Morganelli, the arboretum’s horticultural supervisor. “You only hope to get the population down to a point so you can control it.”

   In manicured lawns, nutsedge goes unnoticed until the water is cut off and the grass dies. But nutsedge continues to thrive in the thirstiest Southern California soils. That can-do spirit rouses gardeners’ ire when its green, thick blades start popping up in landscapes intended for growing fruits and vegetables, California native plants, roses or other desired plants.

  Weeds draw up 75 to 80 percent of the available water and nutrients before other plants get to it.

  “They are the ultimate survivors,” Morganelli says. “You’ve got to control weeds, otherwise everything else that you’re growing is going to suffer.”

  This was recently a heated topic of discussion surrounding the Crescent garden — the arboretum’s reclaimed acre north of Baldwin Lake, which this spring was home to Wildflowering L.A. With the wildflower installation complete, the meadow was mowed and all watering ceased in preparation for the next incarnation.

  When complete, Crescent Farm will be a foraging garden with areas for drought-friendly lawn alternatives such as Carex praegracilis (slender sedge) or Achillea millefolium (yarrow).

  Right now, it’s covered in nutsedge.

  As recently as September, the arboretum considered managing its nutsedge problem with herbicides and then quickly dismissed the idea to the delight of the Crescent’s eco-minded volunteers who had voiced strong opposition.

  Richard Schulhof, arboretum CEO, says “next to no chemicals” are used on the grounds.

  “The vast majority of weed control here is accomplished by pulling,” he says. “Secondly, we use huge amounts of mulch, so it’s an integrated approach. The very last tool we reach for would be an herbicide, and we use that only in extremely limited circumstances and only under conditions that are free of risk.”

  Herbicides are controversial.

  For every study that shows residual traces of such chemicals in people or waterways there is another that contradicts it. Yet read the label of a product like SedgeHammer, which is recommended for nutsedge control, and it cautions, “The use of this chemical in areas where soils are permeable, particularly where the water table is shallow, may result in ground water contamination.”

  Roundup, which is not recommended for nutsedge management, offers similar restrictions.

   The arboretum has decided to eliminate its reliance on such chemicals in the Crescent garden in pursuit of organic certification — a rigorous, expensive process that requires the garden be chemical free for a minimum of three years.

  Nipping nutsedge in the bud before it flowers and goes to seed, or pinching off the blades at the surface to prevent its ability to photosynthesize, are two effective ways of keeping the weed in check. But nutsedge that spreads by underground roots is a lot harder to manage — especially in clay, hardpan soil where it really digs in.


  Woven Earth's mulch mats could also be an effective solution to controling weeds organically.  To learn more about these innovative mulch mats, call us at 949-328-4367.



“When you pull and pull at it to try to get that root out, you send a signal to the plant to put out more rhizomes because somebody is trying to kill it,” Morganelli says. “The act of doing that actually increases the population of the plant.”

While it may seem counterproductive, building up the soil in areas where nutsedge is a problem can also make controlling it easier. It takes no effort to pull the weed from soil that is rich, fluffy and moist, and full of biodiversity, which can be accomplished through the permaculture technique of lasagna mulching — alternating layers of green waste and brown corrugated cardboard (without tape or stickers) covered over with mulch and topsoil.