Community gardens are not at all intended to be the only source of food, it allows a fixed labor cost from a family to produce the greens and veggies that would otherwise have to be purchased ‘fresh’ from the store. That’s it. So you can take someone who is under or unemployed and turn that unpaid time into a replacement for an otherwise expensive food for the family.
You don’t use the garden to grow all the food you’re going to eat, you buy bulk goods like rice and beans, pasta, etc that you can get for low cost and then replace the greens and veggies a healthy person would get at the store with food from the ground which has a fixed labor cost instead of a ballooning dollar cost.
There’s also a thing where most of the practitioners, including very high level ones, don’t have a clue how it works. They know what works for them, that’s about it. All of it is all intent and the wand and words and other trappings are intended to help channel it but are commonly mistaken as the tools doing the job. They would know this in universe if any of them were even passably interested in the scientific method instead of being arrogant rich bastard assholes that I fully detested by the end of the source material.
A fantastic real life corollary was Jacob Aldolphus “Jelly” Bryce, a prominent, arrogant, and primarily lucky FBI agent who had survived a number of shootouts. His method of ‘shoot your pistol from the hip like a madman’ became official government training for many years until someone did a study and rightly pointed out that the technique only really works if you’re naturally coordinated in exactly this way, which Jelly was. For everyone else it was awful training that lost quite a few lives until actual science could show that bringing the pistol up in line with your eye didn’t take measurably longer and allowed you to hit your target much more effectively.
and since the point is the tracking and not the age at all there’s no reason to even try a maturity test. it’s about your identity, nothing more and nothing less, every single time it’s brought up. If they cared even a shred about kids we’d have universal healthcare so as usual it’s just flat out lies to our face.
People think of veg as something with a timer that counts down; you buy it as fresh as it’s going to be and then you have to eat it before it turns into slime.
In a garden the timer is running the other way; every day the food gets fresher and better and bigger, and if you’re planting at the same rate you’re eating the garden becomes a daily food pipeline.
Be aware; gardening is a gateway to canning, because that’s how I keep eating my garden in December