Garden Dweller in any discussion like this the text that immediately comes to mind is VS63. I don't think it is cited very often by modern commentators and it is clear why they don't:
The Bailey version is "63. Frugality too has a limit, and the man who disregards it is like him who errs through excess."
and Epicurus.net has a more clear version: "63. There is also a limit in simple living, and he who fails to understand this falls into an error as great as that of the man who gives way to extravagance."
With the key point being that it is incorrect to look for a one-size fits all formula. "Simplicity" as a goal is as wrong as "luxury" as a goal. The goal can only be defined properly as "pleasure" and the circumstances under which each individual is going to experience the most pleasure will differ by time and place and individual, as you would expect in an atomistic, non-fated, "free will" human situation.
Yes it is true that Epicurus generally recommends a simple lifestyle, but he explains why very clearly: not so that we will never have luxury, but so that we will have no issues when luxury is not available. My view is that this of course makes sense as a general rule, but the problem is that lots of people (natural stoics) get carried away with ANY kind of rule, and they begin to worship the rule and forget that the goal was always, is always, and will always be "pleasure" in the broad sense of that term - including all mental and physical pleasures.
I know we were talking in your earlier thread about the issue of time, and I think that's a huge issue. It's clearly not appropriate to elevate "long-term pleasure" in every case over "short term pleasure" because time is no magical element that turns a long life of minimum pleasures into something that's intrinsically better than a life that is shorter but more filled with "stronger" pleasures.
It seems to me that it's very difficult to put any kind of "measurement" on pleasure other than what we ourselves end up judging it from our own personal perspectives.
This is an area that Elayne has some good ideas in, and maybe she will comment, but in the end the first and most important thing to keep in mind in discussing your question is how individual the answer is, and how it's counterproductive to think or look for a general rule that everyone must follow all the time.
So to tackle your last two specific questions:
"Does Epicurus recommend eating simple food and growing one's food in a garden?" << There are definitely texts that talk about bread and water and cheese as illustrative of simply living while still being able to compete with Zeus for happiness, but there is absolutely no evidence that the Garden itself lived that way on a regular basis, and I think Epicurus was making a rhetorical point in the context of the issue we are addressing here, that proper lifestyle is contextual. Remember what Epicurus disposed of in his will -- he had significant property, and even slaves, and there is no way to reconcile that (other than calling him a hypocrite) with the idea that he recommended across-the-board frugality.
"Would living in a garden and harvesting one's food be a life to strive for as a student of Epicurus?" It might be, or it might not, depending on circumstances. I know that I personally spend as much time in "the country" as I can, and I can see myself raising vegetables or even chickens in the future, but I do not now and have no immediate plans to do so. If you personally would enjoy that, then you should. But the idea of devoting yourself to a farm lifestyle if you really don't like doing it is likely going to make no sense at all from an hedonic calculus point of view.
Maybe the final point to make is that it's empowering or even scary to think how much of all this is in our own hands, and that we have to decide for ourselves, but I think that's compelled by the nature of the Epicurean universe in which there are no gods telling us what to do and no "ideal patterns" to go by either -- not even any absolute standards of virtue or justice. We're really no different than any other animal -- we're here for only a short time and the best we can do for ourselves is use our time as productively as possible -- with "productively" being judged by the "feeling" we get from our life.