My small soil plots were put near the world gate in my Imperial Palace, though they didn't show up until three days later, which surprised me because then I set some medium sized ones down and they appeared right away. Now my small soil plots are awkwardly bunched together like the Olympic Rings.
This is very likely a glitch/bug. The plots you placed should have appeared right away. You can use the plow utility gardening spell to remove the plots if you're finding them unattractive or unnecessary.