Our current asparagus beds are about 10 inches deep and they’ve been OK to see perennial growth and basic crown development. Our “big picture, long term” goal with our current, small asparagus beds is to allow transplanting of our crowns into a more permanent asparagus gardening location. We didn’t dive into it much here (as we’re learning about asparagus, still!), but there’s male and female asparagus plants. Our goal with our current beds is to create male plants, which yield higher and to ultimately discard the female plants. Once we’ve got our more permanent asparagus beds in place, the idea is that we can raise asparagus by seed, sex them over 2-3 seasons (since we don’t have a long enough season to see definitive results in just one season) and basically get on a transplant schedule of every other year. These “permanent” beds will be in-ground, and thus as deep as the plants want to root. Nonetheless, we’d be comfortable even with relatively low depth beds, around 10 to 12 inches.