Weeds! 😡

[GoodFriendMike]

There are selections of Oxalis cultivated for their eatable corms.

I used to grow a few Andean varieties of Oca that were not bad.

 

[Charlie Dodgson]

It’s almost impossible to get anything more than the bit above ground

When it becomes stubborn in pots: I lay the plant down (preferably on a bench), pull the pot back about 4", remove the top 3 inches of soil, then stand it back up and add new soil (preferably 3/4 cured compost + 1/4 all purpose sand).