Thanks for all comments.

SFG is Square Foot Gardening. I do pull most of the roots, but the
finer ones inevitably get left behind. Like I mentioned, I've only
been doing this for a couple of years so just looking for advice and
trying to learn from the folks here with the experience and
knowledge. I am trying to be "natural" by not using artificial
fertilizers or pesticides (compost instead), so thanks George for
introducing "Fukuoka Farming" - that's a new one to me and I'll check
it out.