Now that planting season is nearly wrapped up, it’s time to start thinking about protecting plants from their age-old nemesis: weeds.

Matt Cutulle, assist professor of vegetable weed science at Clemson University’s Coastal Research and Education Center, says weeds are behind a $32 billion annual crop loss due to taking necessary nutrients from the soil. According to Cutulle, effective weed control starts during the weed-free period — which varies based on the crop, how the crop is planted, whether the crop is seeded versus transplanted, etc. A typical weed-free period is about 6 weeks.

This 6-week window is when growers can maximize yield potential. After that critical timeframe, focus should shift to preventing weed seed production.

Cover crops are capable of being a formidable weed-management tool, but only if growers have a solid plan in plan beforehand for terminating those cover crops at the end of their growing season, such as roller-crimping or another termination method.

Geoff Zehnder, director of Clemson University’s Sustainable Agriculture Program, notes that vegetable growers usually struggle with determining the optimal time to plant cover crops to maximize biomass. Adequate amounts of biomass from cover crops is what suppresses weeds growth.

Clemson University experts share the cover crops that have helped vegetable growers the most successfully with weed suppression include black oats, buckwheat, crimson clover, field peas, foxtail millet, hairy vetch, spring barley, spring oats, sunn hemp, winter barley, winter rye and winter wheat.

When managed properly, cover crops can successfully co-exist with vegetable crops—who knew?