Control weed growth around asparagus plants by pulling the weeds by hand or salting the weeds. Pre-emergent or post-emergent herbicides also work to inhibit weed growth.
Hand pulling weeds around asparagus plants is one of the most effective methods of weed control for small areas. This method is fairly simple and has the added benefit of not adding toxins to the soil. When hand pulling weeds, dig down into the soil to grasp and remove the roots, a method that reduces the chance of the weeds growing back.
Adding salt to the weeds can also kill unwanted plants, but it can burn young asparagus shoots or build up in the soil. High salinity in the soil can inhibit plant growth and not all weeds are vulnerable to salt. Use pre-emergent herbicides in the spring to keep weed seeds from germinating or apply post-emergent herbicides after the last harvest to prevent weed growth the next season. When applying herbicides, avoid applying it to the asparagus. For a non-toxic option, use corn gluten meal as an alternative to pre-emergent herbicides.
Apply four inches of straw mulch to an asparagus bed to inhibit weed growth. The mulch has the added benefit of encouraging asparagus growth by keeping the soil cool. Shredded newspaper also works in place of the straw.