The grass has to come from seed...could it be *moss*, which is windblown for the most part?? Any pics? The soil could have had seed in it from a bird or a bag of feed-seed nearby maybe? I sometimes inadvertently placed a pot under a bird-feeder and the birds would drop seed into pot without me knowing. Weeks later, I'd have a field-day picking tiny sprouts out
At least the *birds* were happy, I guess. Now, I look up
before I set stuff down
Its never a bad idea to 'blast' stuff off with water before applying 'poisons', fwiw. Just careful to not blow out dirt or whatever. Friction of some sort is always preferred, but nothing wrong with poisons when used properly and appropriately.
I use the term poison very loosely here - I do NOT mean stuff like diazinon or such, LOL
Are these bugs within soil, too? Do they crawl around, yet fly when disturbed? (fungus gnats? organic-based soil?) Just curious...