Grossly overstated as per the peddling/commercial sale of this overpriced toy. You're gonna feed a family of four out of that, huh?
Grains, legumes and meat make up a substantial portion of a healthy diet. Iceberg lettuce and most other lettuce for that matter, is satisfying for a short time but delivers few vitamins and minerals, and very little energy that a body needs.
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I grew-up growing a garden and had one for most of my adult life. You have a stressful life? Get out there and do something useful that is also relaxing.......get your hands dirty and some dirt between your toes in a real garden which makes you appreciate life in all it's wonders.
You insist on living in a high density area without a vision of grass or trees or honest to goodness soil of the earth? Well, you get what you deserve.