Sir,
I have been organic gardening for 50 years. At one time I had the largest organic produce gardens in northern Ohio. I’m good at it.
Some years ago, some people staying with me asked if they could plant a little Amaranth in one of my gardens. They related how Amaranth may be the most consumed food in human history. It is super productive, and very nutritious. I allowed them to plant some. That was a big mistake.
If you are not really careful to harvest every seed, it will spread like wildfire. Within a year or two, it will be all over your property. If you want weed-free gardens, this is not the plant to encourage. It grows tall and thick, and can and will choke out all your other vegetables. It took me a huge amount of work to get rid of it.
Amaranth is good food, but be careful what you ask for. If you must have it, plant it a long, long way from your other gardens. Harvest every bit. And don’t let the birds spread it. – Jim in Ohio