The Weekly Weeder: Natural Weed Control

Notice the old leaves under the rose, and the 4 x 8 sand paths.

            Weeds are taking over neglected portions of our cities and countryside, making them ugly, disorderly and unsafe.  Flowering weeds are often ugly, always disorderly, and once they dry out, they are a fire hazard.  If not killed before going to seed, they spread themselves around; they are a nuisance that multiplies.  Whole city subdivisions have burned in recent decades, and some small towns as well.  Oregon, Washington and Arizona burn in the summer, California in the fall, and large expanses of the Great Plains in dry winters.  When city weed codes are well enforced, cities don’t burn. 

          The most dangerous weeds are annuals that seed and dry out in a season.  They make many seeds, some of which can last for years in soil before they sprout or rot.  But their roots don’t need to be pulled to kill them; all of their top growth comes from their crowns, the part of the plant between the roots and the top.  Cut them under the crowns, and they are gone.   

          You can cut them under their crowns with scissors or a knife, which is great for going after individual weeds, but is relatively slow.  Still, this is the best way to handle seeded puncture vine, a noxious weed that pops bike tires as well as poking bare feet.  Cutting or pulling are the only ways to take weeds out selectively in lawns, beds and borders.

          You can also beat the crowns out of the soil wholesale with a string trimmer.  This works best when the plants are young and not yet seeded, and the soil is relatively soft.  It has to be repeated to catch newly sprouted annuals and re-growing perennials.  Done often and long enough, it can kill out perennials as well.

          You can mulch with leaves, compost, wood chips or bark to smother small plants and stop seeds from sprouting.  Most very small seeds need a touch of sunlight to sprout, and nearly every newly sprouted plant can be easily smothered with 2 inches or more of dense mulch.  Avoid fine bark and non-sifted bagged bark with fines; bark’s natural preservatives leach downward and kill soil life. Larger barks do not kill soil, but ¾” nugget and larger bark are not dense enough to smother at 2” deep.  Walk-on fir bark is most effective at smothering and staying put.

          Leaves are the most effective mulch, though some tend to blow around a bit.  They dry quickly on the surface and make a lousy seed bed for whatever falls on them.  Leaves and compost also feed soil life, which makes the soil soft for pulling weeds and provides habitat for good bugs like soldier beetles, spiders, centipedes, millipedes, ground beetles, and earwigs.

          You can spread an inch of 4 x 8 sand (river sand sifted to ¼-1/8 inch) to bring seeds up and then cut under them with a hula hoe (AKA scuffle hoe and stirrup hoe), which is made to slide under crowns.  Sprouting seeds put their crowns at the top of the sand, making it easy for the hoe to slide beneath them.  This is particularly good for maintaining paths and open areas.  4 x 8 sand is also good for establishing lawns from seed, as it covers the seed, brings it up by warming the soil, and protects roots and crowns as they grow.

          Roundup herbicide (glyphosate salts) should generally be avoided, simply because it also fertilizes for broad leaf and annual plants and feeds worms and pill bugs, which in turn attract moles.

           

 Rycke Brown, Natural Gardener       541-955-9040        rycke@gardener.com