Space Gardening and you

This article in Utne says: "Researchers suspect that space gardens won’t be the primary source of sustenance on galactic missions, but fresh-picked vegetables will be a welcome addition to the cycle of processed and packaged meals.
“Along with reducing trash and launch mass requirements, such crops would give astronauts a little diet variety and psychological lift,” writes Witze. After all, even astronauts love to eat local."

It's a great little article with a good link to the source, and that's great for my research purposes, but I'm just left with the question: Why can't astronauts grow all their own food? The ideas exist for making frakking skyscraper farms, and most of the basic tech has already been developed. If new tech needs to be developed, it has a reason to get made right here. If astros do it, then other people can, too, and a ship headed to Mars is not really so different from a skyscraper. Meat might be a problem, but soy grows just about everywhere as far as I know, and there are plenty of plant-based forms of protein.

And if they're really planning a colony on Mars, wouldn't it be a jump-start to that colony's survival to already have plants that are alive and growing? Rather than starting from scratch when they get there?

I do agree with the psychological boost, though. Plants are proven to be soothing--we're wired to unwind in nature. Plus, they will give people something to do in the long stretches of time between needful emergencies (if all goes well). Maybe they can set up a whole hydroponics bay, and each astronaut can grow something just for pleasure in a corner of it, something not necessarily needed for food?

I'm pretty sure this is the wave of the future. I have a basically science-fictional, forward-looking mindset, and I think if the tech is there, if the chance to use it is there, we should all jump on that bandwagon early and enthusiastically before we have to scramble on out of dire need later. I mean, if it works on the way to Mars, then it'll work in orbit, which should be much easier, really. We could have space-farms feeding space colonies. We could claim all the living room this breeding species needs. So lets go do it.