SAN LUIS VALLEY — This summer, my garden reminded me of what helps and what hinders in the management of weeds.
Early in the summer, we took out a section of old fence for an outdoor project. This created an area of bare soil in the yard and it’s where we stacked building materials used during the project.
Weeds love bare soil! They don’t have to compete with healthy plants for sunlight, nutrients or space. And this summer we had so much rain, which I was grateful for but so were the weeds. The combination of bare soil and rain, the disruption of the soil when we removed the fence, and the opportunity the weeds had to grow undisturbed (we went on vacation), well it was a weed party! Fortunately, a small party, but one nonetheless.
Weed seeds get into our gardens a number of ways, from birds and animals carrying them in, to the wind blowing them, to tumbleweeds dropping as they roll on by. Occasionally, we bring them in inadvertently when we add topsoil or mulch that contains weed seeds. It’s disturbing to realize that a single weed can produce thousands of seeds. It’s also discouraging and honestly a bit alarming to realize that soil itself contains millions of weed seeds, the so-called weed seed bank, with some seeds surviving underground for decades just waiting for the opportunity to sprout. It’s a reminder to disturb our garden soils as little as possible.
Management can be broadly divided into cultural and chemical methods. Cultural methods include hand-weeding, hoeing, mulching, and mowing. Early in the season, it’s easy to pull up small weeds by hand without disturbing too much soil. Later in the season, larger weeds can be cut off at the soil level. Many annual weeds will die when cut this way. Perennial weeds have a network of roots and rhizomes that allow them to survive this, but over time (often years) without leaves above ground, the roots will weaken and some perennial weeds will die.
The other half of my summer story involves the areas where I had used good cultural methods to prevent weeds, most notably use of mulch, and I’m glad to report the results were good.
I cannot praise the value and benefits of mulch enough. In addition to helping reduce water use, decreasing wind erosion, and giving a more finished appearance to our gardens, mulch provides a great barrier to weeds. Three to four inches of weed-free mulch blocks sunlight from reaching the soil, preventing weed seeds from germinating. And it smothers any small annual weeds attempting to grow.
A healthy lawn and landscape plants are great weed deterrents as well because they can often outcompete weeds. Using a schedule of deep, infrequent watering benefits lawns and gardens, and is hard on shallow-rooted weeds. Mowing grass to a height of 2 1/2 to 3 inches and leaving grass clippings on the lawn contribute to a healthy lawn. In the areas where I had ample mulch, and a healthy lawn and landscaping, there were only a few weeds when we returned from vacation, but no weed party.
Although our gardens will never be weed-free, we can have a positive impact on weed control by thinking about ways to stop weed seeds from germinating (no bare soil, minimal disruption of soil, mulch) and ways to prevent weeds from producing seeds by pulling them when small or cutting them off at the soil level before they set seeds. Limited use of selective herbicides can at times be used to supplement cultural methods, taking care to read labels and apply them correctly.
Let me know what worked in your garden this year! Please share any helpful hints for weed control you’ve used. Send me an email at SLVgardening@gmail.com.
