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NDSU Extension Service, Published April 13 2012

Garden without weeds

NDSU Extension Service

As vegetable gardeners gear up to plant homegrown produce, dormant weed seeds lie buried in the soil and ready to sprout the instant the right conditions occur.

“Sprout they will, leaving fledgling beans, zucchini, herbs and tomatoes to compete with fast-growing, naturally adapted weeds for space, water and nutrients in the garden,” says Ron Smith, a North Dakota State University Extension Service horticulturist. “Ironically, the very act of preparing a vegetable garden encourages weeds. Turning and tilling the soil, plus creating the furrows to plant the vegetable seeds, exposes these dormant weed seeds to the light they need to germinate and grow.”

Most gardeners know to lay down a layer of mulch on top of the soil to deny weed seeds the sunlight needed to sprout. However, fewer know there’s an organic pre-emergent option for vegetable gardens that can double the weed-fighting power of mulch.

Research at Iowa State University found that corn gluten has properties that prevent weed seeds from germinating. This makes corn gluten an effective organic pre-emergent weed preventer in food crops. The corn gluten is usable throughout the growing season, even up to the day of harvest.

An easy-to-apply granular corn gluten option is Organic Preen Vegetable Garden Weed Preventer. It comes in a jug-handled bottle with a flip-top shake applicator. When sprinkled on garden soil or mulch, Organic Preen stops weed seeds from sprouting for up to four weeks per application. During that period, it also stops weed seeds carried in by wind, birds and animals from growing.

“Pre-emergents don’t kill weeds because they’re weed preventers, so existing weeds must be removed manually or killed by other means,” Smith says. “The nice thing about pre-emergents is that you can apply them right over your established or recently transplanted vegetable plants. They should not be applied to areas in the garden that have just been seeded. The first true leaves of the vegetable species must be fully open before an application can be made.”