So, I've been getting into gardening, and I got an idea. The one good element of social games back in the day, was that friends COULD help you on your gardens. In those games, it was always mandatory in the games themselves. Not here, however.
My idea is that when you're visiting a friend's house, or exploring the Housing Tours system, you can cast gardening needs and pest spells. Every need or pest you successfully take care of gives you a small amount of gardening XP, and a small sum of gold.
You can harvest any plants you find, and they wont count towards the owner of these plants' harvests, nor will they finish off elders (Elders only provide their mature drops due to such). However, each harvest requires you to have spent 1 energy at that castle on maintaining its crops, to keep people from going from castle to castle and making tons of profit off others' gardens.