Margaret comments in The Survival Gardener community:

I have an amaranth story. Two years ago I purchased an amaranth seedling just to see how it did. Well it grew about two feet tall, was full of holes from some insect and eventually it just went into the compost pile. About a month ago I topped off a garden bed with compost from that bin check this out:

That is epic.

Amaranth really likes broken ground, and when it self-seeds it can be quite vigorous.

It’s also amusing that the seeds came through the compost pile. In my experience, it’s quite common to have seeds survive composting, even when you attempt to compost “the right way” by hot composting. Seeds are good at surviving, and boy do they love compost.

We have purple amaranth all over the place this year, since some went to seed last year and left seeds in our gardens, in our potting soil, and across the plant nursery. It’s okay – they’re pretty. And they’re much better than their spiny pigweed cousin.

Seeing Margaret’s runaway amaranth makes me want to throw seeds all over the food forest and see what happens next spring. Daisy has the purple type for sale in her seed store already – and I have some golden giant that would be fun to throw out there as well.