If you have a small bed, you can handpick weeds as they emerge, being careful of the asparagus crowns. Mulch also will help to supress them, and some gardeners find that a 3- to 4-inch layer of sawdust does the trick. Avoid placing the sawdust right near the crowns, as it can form a crust—this crust helps to keep weeds down, but can also inhibit the asparagus from getting water. Another concern is that the microbes that break down sawdust may use up nitrogen; keep an eye out to see if your plants might need a little nitrogen boost during the growing season (turning yellowish or pale green). An alternative mulch would be to use about 4 to 6 inches of straw (not hay).
If you have a small bed, you can handpick weeds as they emerge, being careful of the asparagus crowns. Mulch also will help to supress them, and some gardeners find that a 3- to 4-inch layer of sawdust does the trick. Avoid placing the sawdust right near the crowns, as it can form a crust—this crust helps to keep weeds down, but can also inhibit the asparagus from getting water. Another concern is that the microbes that break down sawdust may use up nitrogen; keep an eye out to see if your plants might need a little nitrogen boost during the growing season (turning yellowish or pale green). An alternative mulch would be to use about 4 to 6 inches of straw (not hay).