Grow For It: Weed wars

By From page B3 | March 20, 2013


PAULA BERTRAM, Master Gardener. Democrat photo by Shelly Thorene

“Plant and your spouse plants with you; weed, and you weed alone.” — Jean Jacques Rousseau Really.

There’s a lot to admire about weeds; they’re akin to guerilla fighters. Tough, resilient, adaptable, they can thrive in poor conditions, seemingly disappear under direct attack and then reappear in a flanking action.

Did you know a single weed seed can lie dormant for more than 1,000 years and then sprout?

No wonder we feel like we’re in a constant war with these pesky plants.

But what is a weed?

The simplest definition is a plant growing where it is not wanted. This makes sense: Rye grass is a real pain when it invades your lawn or veggie garden, but may be terrific forage in a horse paddock.

That variegated ivy that was so cute in the Mother’s Day pot with the balloon could now be completing a hostile takeover of the Japanese maple.

A couple of simple concepts about weed types. Stay with me now: it’s really easy.

There are annual and perennial weeds.

Annuals (think zinnias or marigolds) are plants that complete their whole life cycle in a season and then die. Annual weeds are the same — their seeds sprout, the plants grow and flower, then they die.

The most effective way to defeat annual weeds is to prevent seeds from forming. More on this later.

Common annual weeds are rye grass (Lolium) and purslane (Portulaca oleracea).

Perennial weeds are a lot more tenacious. They live on from year to year, and have larger root systems. Gardeners have to either catch them as young plants in search-and-destroy missions, or attack them over time to reduce their vigor.

Dandelion (Taraxacum officinale) and oxalis (or sorrel, Oxalis corniculata) are examples.

How do gardeners keep these guys under control and/or in their proper place? The methods fall into a few categories: cultural, mechanical, physical and chemical.

Cultural: This means giving your desirable tomato or rose bush a competitive edge. First of all, select the right plants for the garden site. For example, if watermelon takes 110 days of high summer heat to mature and you live in shady Pollock Pines, the weeds are going to outcompete the poor melon every time.

Make the soil as hospitable to the plants as possible with proper tilling, irrigating, fertilizing, rotating crops and avoiding soil compaction. Believe it or not, just these basic gardening practices will eliminate 60 to 70 percent of a weed problem.

Mechanical: This is the old-fashioned hoeing, digging, pulling, mowing and chopping … going “mano a mano” with the weeds.

My favorite tool is a hori-hori knife, which looks like a vicious serrated bayonet. As with all sharp tools, employ proper safety techniques and its use can be very satisfying. Make sure to get rid of those annual weeds before they go to seed — like, put down this paper and get outside now.

Physical: Mulching can be a very effective way to prevent weed seed germination and weed growth.

A variety of mulches such as compost, newspaper, straw or a combination of these should be placed on the ground several inches thick. Inorganic mulches are things like landscape cloth or plastic. These sheets can be covered with more attractive materials such as pebbles or bark. A special use for plastic sheeting is called solarization. The weedy patch is watered well, then securely covered up with clear plastic for 2 to 3 months during the summer (weight the edges down). The heat that accumulates under the plastic kills weeds and voila, a nice clear patch of soil to plant.

Don’t forget the amending, tilling and so forth before you plant. Solarization can also kill or drive away beneficials, such as worms but they will return.

Chemicals: In the words of the UC Davis Master Gardener Handbook — “the last resort.” Because herbicides can harm many plants (not just targeted ones), and are implicated in the disappearance of frogs and other beneficial citizens of the yard, they are the most problematic way to control weeds.

Discussion of safe use of herbicides such as diquat dibromide, 2,4-D and Roundup (glyphosate) is complex, and beyond the scope of this article. If you use chemicals, make sure to read all labels and follow instructions to the letter. And don’t let herbicides drift onto your vegetable patch or your neighbor’s prize-winning rose bush.

Spring is almost here — happy gardening.

Join Master Gardener Thorne Barrager on Saturday, March 23 from 9 a.m to noon for a free public class on Backyard Chickens. Why raise chickens? Find out how easy and inexpensive it is to maintain chickens, how they provide chemical-free bug and weed control in a garden, and can manufacture one of the world’s best fertilizers.

The class will be held at the Veterans’ Memorial Building, 130 Placerville Drive in Placerville.

Master Gardeners are available to answer home gardening questions Tuesday through Friday from 9 a.m. to noon by calling 530-621-5512. Walk-ins are welcome at the office, 311 Fair Lane in Placerville.

For more information about the public education classes and activities go to the Master Gardener Website at Sign up to receive the online notices and e-newsletter at You can also find Master Gardeners on Facebook.

Paula Bertram

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