More on winning the war on weeds


Editor's note: Part 1 of this two-part series published last week and is available online at

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are weeds so weedy? Why don't hybrid tea roses or fresh strawberries overrun our yards and gardens the way weeds do?

Mother Nature created overachievers that subdue other plants by their sheer invasiveness. Although we call them "weeds," humans are often responsible for their spread. Immigrants brought dandelion plants across the ocean to North America as a tasty salad crop, and my how they've grown.

Weeds are undoubtedly the most common gardening problem. Here are tips for subduing them in different locations.

Vegetable garden

• Annual weeds, sprouting each year from seeds, are the main types encountered.

• Yearly rototilling prevents most perennial weeds from establishing, with the exception of thistles and quackgrass, which continually resurrect themselves. Apply herbicides in fall to patches of quack and thistles, and again in spring, as they emerge before garden planting time.

• When planting vegetables, mark both ends of each row with inexpensive or homemade stakes. Knowing where the vegetables will emerge lets you hoe or cultivate more accurately between rows early in the season when weeds and vegetables are both tiny.

• Shallow cultivation when the soil surface has dried slightly after rains or watering can be done quickly with a well-sharpened hoe or tined cultivator. Attacking weeds while tiny is the key to vegetable weed control.

• Weeds within rows usually require hand-pulling or precision weeding. I use a table knife.

• Weeding can be reduced by mulching spaced plants like tomato, cabbage, potato and others with straw or grass clippings.

Annual flower garden

• Annual weeds are the most prevalent competitor, and hoeing, cultivating and hand-weeding are good options until the plants cover the soil, out-shading weeds.

• Weed-preventer products like Preen can be sprinkled over well-prepared, clean soil after setting out transplants. It kills annual weeds as they sprout, but won't prevent perennial weeds that arise from underground roots or rhizomes.

Perennial flower garden

• Perennial weeds are the biggest challenge, as quackgrass, dandelions and thistle intermingle among perennial flower clumps. There are no chemicals that prevent their invasion from underground structures. They must either be sprayed with herbicides after invasion, hand dug or mulched to smother.

• Actively growing quackgrass can be killed by spraying with grass-killers like Ortho Grass-B-Gon or Bonide's Grass Beater, which won't harm non-grass perennials.

• Broadleaf perennial weeds can be spot-sprayed with Roundup or 2,4-D (choose amine forms instead of volatile ester) carefully avoiding contact with perennial flower plants. Fall is the best time.

• Roundup is now available in gel-form, making it easier to safely dab it onto weeds.

• Preen can be applied to prevent annual weeds from sprouting.

• Mulches used on bare perennial bed soil with no underlayment need to be about five inches thick to keep weeds in the dark and inactive.

• If landscape fabric is used, mulch depth can be reduced to about two inches. Cardboard or newspapers (laid 30 sheets thick) can be used as effective organic underlayments that eventually decompose.

Landscape plantings

• Most shrub plantings are mulched with wood products or rocks, often with fabric below. Preen weed preventer applied each spring can reduce weed seed germination, which happens when weeds easily find a small growable spot.

• Spot-treat with Roundup or 2,4-D as needed, carefully avoiding contact with desirable plants.

• A weekly walk around a clean landscape, while enjoying its beauty, is usually enough to nip weeds in the bud by hand-pulling.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler's Greenhouse in Fargo. Readers can reach him at

He also blogs at " target="_blank">