Giant amaranth plants

How long to make this height?

There you are again....I think you're very tiny Sunflower.:o)

The amaranth in this picture was 23 feet 2 inches and was started as a cutting indoors around the end of March, if I remember correctly. It was pretty much full height by the end of September. I have direct sown them in the garden in late april and was able to get them 21 feet tall by the mid-October.