Since I thought of this a long time ago (but didn't do it since money is useless in this game so I didn't really care anymore), I wouldn't be surprise if others have thought of it or done it already. What I mean is buying multiple small houses on multiple alts in order to gain access to the garden. Small houses are 10 times less expensive than medium houses and 20 times less than large, making them MUCH more cost efficient if you just want the garden.

A solution for this is to make houses limited to one per account per world and let all alts on the same world share a house. There are down sides to this as well but with the limited housing spaces, it wouldn't be a good idea to let multiple alts each have a house anyways.

Another solution would be to increase the garden limits per house, which would drive down the prices of crops and eliminate or lessen the advantage of having multiple houses.

Yet another would be to increase the prices of small houses. Even though small houses are cheap, only the fairly wealthy can do this since it requires a fairly large investment to buy multiple of them. Given my knowledge of the economy in this game and how easy or hard it is to make money if you put in some effort, I think 2-4 mil is good price zone for small houses so I don't particularly support this idea.