Thinking about it some more, it would probably be a good idea if, instead of a daily message saying I should really buy Sylvia that goes on for multiple in-game months, it said that saving up for Sylvia is taking a long time and I should buy more bar upgrades. The current messages give the impression that Sylvia should be prioritised over other money sinks, but the cost of fully upgrading the bar is so much lower that it’d be much faster to do that first.
I still think it’s likely a bug that the greenhouse needs buying before garden beds can be upgraded.