Garden Variety: Tips for keeping weeds out of your vegetable garden

As summer-loving vegetable plants begin to thrive in the warm Kansas sun, summer-loving weeds are taking off too. They appreciate water, fertile soil, and light as much as cultivated plants, and unfortunately some of them are a challenge to control. The best approach uses a combination of prevention techniques and physical removal. Many gardeners also use cultivation, and some use herbicides (organic or conventional). What works best depends on the growing site, types of weeds involved and personal preference.

Why worry about weeds at all? In vegetable gardens they compete with cultivated plants for water and nutrients, which reduces produce quality and yield. Some weed species worsen pest problems by serving as alternate hosts for insects and plant diseases. Weeds also make it difficult to care for and harvest cultivated crops — what seems like a little bit of grass now will soon hide an entire cucumber patch if left to grow.

The other bad thing about weeds is that many species reproduce exponentially. A single crabgrass plant is reported to produce as many as 150,000 seeds. Not all of them will sprout next year — some will stay in the ground and germinate the year after or the year after that when conditions are right.

Prevention is the most effective method and most crucial step for managing weeds. Mulch works well at preventing light from reaching weed seeds and stimulating them to germinate. Ground cover is effective at outcompeting weed seedlings.

To use mulch for weed prevention in the garden, place straw, prairie hay, wood chips, pine needles, compost or other lightweight plant-based materials between rows and between plants. Straw and prairie hay are favorites for most gardeners because they are easy to apply, serve their purpose well, and can be incorporated into the soil at the end of the growing season or simply left on the soil surface. Pine needles and compost are similar but may be more difficult to apply and incorporate. Wood chips take longer to break down and work best if creating permanent walkways between rows.

Ground cover would also be a more permanent installation. An example of this would be planting lawn grass between rows. The idea is to leave the rows where they are from year to year and be able to walk between them on the grass.

Avoid using grass clippings or fresh yard/plant waste in the garden without composting them first. These fresh materials can tie up nitrogen in the soil as they break down and keep cultivated plants from being able to use it.

Old newspapers, paper, chipboard, cardboard and similar materials are often recommended as mulch or ground cover between rows. They need to be weighted down to keep them from blowing away. Some gardeners say they work wonders and break down quickly, while other gardeners express concerns about potential contaminants from printer inks and say these materials are slow to break down.

Weed control fabric, also called landscape fabric, could be used between rows as well. Use it with caution, as it affects air and water movement into the soil surface. It also needs to be weighted or stapled down to stay in place.

Once weeds have emerged, use a hoe or small cultivator to physically remove them. Hand-pull weeds that are growing up next to desirable plants. Small weeds are always easier to remove than large weeds, so give the garden a little time for this activity each week.

Place or replace mulch in weedy areas immediately after weeding to prevent additional weeds from growing.

If weeds get big, mowing them or using a string trimmer may be needed and is better than leaving them to produce more seeds. Keep weeds from flowering and producing seeds as much as possible throughout the season even if a few are left to grow.

Cultivation is a traditional and popular method for weed control between rows. Use a rototiller on a shallow setting or a manual cultivator to destroy weeds. This method quickly and efficiently takes care of existing weed problems, but also brings more weed seeds to the surface to germinate. Mulching after cultivation can prevent regrowth.

Finally, herbicides are an option and may be favored for especially difficult plants such as bindweed or poison ivy. There are some organic options with acetic acid and other products, and many conventional options. Always read and follow label directions and be careful to avoid getting any kind of product on desirable plants. Avoid using homemade products and anecdotal recipes, which can damage nearby desirable plants, cause detrimental salt buildup in the soil and are often ineffective.

— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.


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