Answer: There are many forms of amaranthus ranging from "Love-Lies-Bleeding" to "Pygmy Torch"; unfortunately I'm not sure exactly which type you are calling a "hanging" type, but they are all annuals. In my experience, however, the seeds take so long to mature that it is difficult to harvest viable seed for replanting. For the same reason they do not self sow reliably. In addition, if the plants you grew are the result of hybrid seed, the seed they produce may or may not be viable and any resulting plants may or may not look like the parents. To be sure of good germination and the plants you have in mind, you might wish to purchase fresh seed each year.
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