"bescherte" is a verb in this sentence, your assumption was right.
As Volker Landgraf said, mostly "bescheren" is used in context with Christmas, but you can also use it when something has been produced by an action (a nice example I found: Seine Marijuanasucht bescherte ihm Probleme mit der Polizei - His marijuana addiction brought him trouble with the police), or when someone gives/gifts something to somebody else. When used in a positive context, like the sentence you posted, it actually is meant to be positive. In a negative context, like the marijuana example, it comes with quite the sarcastic undertone.
"darin" - I believe that one point of misunderstanding has not been addressed: I believe that you translate "schulen" in this sentence as the noun "schools". If I interpret the last part of your question correctly, that is. It does mean "to school/teach someone in something" though. Capital letters are quite critical in the German language ;)
So "darin" is indeed a reference to what the garderners are schooled in, i.e. not stopping to think after the planting is done.
By the way, there is this amazing online dictionary I'd like to tell you about:
It comes with short examples and a ton of links to forum discussions for most words that are difficult, like "bescheren".
Hope I did everything right, that's my first answer on here!