No, this depends entirely on your employment contract. (Though I do agree that presumably a groundskeeper would not have intellectual property clauses in their employment contract) I've worked for two companies and they had different clauses; one said something to the effect that they owned any IP in their business interest (regardless of whether it was created on company time or company equipment); the other was narrower and said that they owned IP created outside of work only if it was dependent on company confidential information.