I hate to be the bearer of bad news, but nothing I know of, short of Jack's Magic Beanstalk, is going to be able to compete with the roots of a mature fig. Figs by nature have invasive root systems themselves. IF you could find something that could compete for water and nutrients on an equal level with the fig, you'd be injuring the fig in the long run. Of course, in Z9 your options for plants is larger than it is here in Z7, but it still comes down to the fact that figs are very greedy, lol. I've even tried growing potted plants under a bare-legged fig, and found that I had to move the pots regularly or the fig roots invaded the pots in a matter of days. I ended up putting concrete stepping stones under the pots to keep them out of contact with the soil.

John

you mean fig roots snuck into the drain holes? whowzers? I already planted my hardy begonias under Celeste but it won't be much trouble to move them. What a waste of garden area.