I have an asparagus patch that is really weedy. How harmful would it be to run a tiller over the top of the soil? When would be the best time to do this? Thanks.

Julia, Its too late to do it now but a shallow tilling can be done in the dormant season. Right now I would suggest hand pulling until harvest is finished in June then hoeing could be done in addition to hand pulling. Be sure you are not using weedy straw over the beds. In dormant season they could also be mulched with compost to help suppress weeds and fertilize.