Once you’ve grown amaranth, the seeds are easy to harvest. Despite their small size, you can harvest a large amount in a small amount of time because the tassels themselves are quite large.
Just to give you a reference, you can usually get about 20 pounds of wheat per 1002ft of growing space, and about 10-15 pounds of amaranth in the same amount of space. So your yield with amaranth will be about 1/2 to 3/4 as much as wheat, but it is, in my opinion, easier to harvest (and prettier to grow).
The seeds are ready to be harvested when they begin to fall from the tassel/flower head, usually beginning in mid to late summer, depending on your climate and when you planted your amaranth. You can give the tassel a little shake and if you see a few seeds fall from the tassel, it’s time to cut the tassel and harvest the seeds.
To collect the seeds place the tassel in a cloth bag and thresh it to free the seed. Or place the whole tassel in a large bowl, and rub the tassel between your hands to release the seeds.
You can remove the chaff in a couple of different ways – either with different sized sieves, or by using the ramp method.
If you use sieves, you can pour the seeds over a sieve stack and shake. With different sized sieves stacked from the smallest on the bottom to the largest at the top, there will be one sieve that will catch the majority of the seed and little of the chaff. After shaking the seeds/chaff through the sieves, simply pull the sieves apart, and find the one that contains the seed.
If you have a handful of kitchen sieves, just sieve the seeds & chaff with several different sieves until you’ve gotten rid of most of the chaff.
Using just my kitchen sieves, in the above examples in the pictures, gave me about 3/4 cup of seeds in about 3 minutes time (including cutting the tassel, rubbing the seeds out, and sieving). It doesn’t take long at all. Just another reason to love amaranth. 🙂
Or, because the seeds are tiny spheres, you could use the ‘ramp’ method (or the ‘blow and fly’ method): Using a cookie sheet and a cutting board, set the cookie sheet flat on the counter, and form an angled ‘ramp’ with the cutting board. Pour the seed into the cookie sheet, and blow toward the ramp. The seed will roll up the ramp and roll back down, while the petals and other chaff will be blown beyond the cutting board. (Which means that, if you don’t want a mess in your kitchen, this might be an outdoor activity.)
Amaranths flower heads/tassels contain both male and female flowers. Amaranth pollen is very fine, and amaranths are mostly are wind-pollinated. Amaranths can cross-pollinate with other amaranth species, whether domestic or wild.
To prevent cross-pollination with other amaranths, including wild amaranth species such as palmer pigweed, the tassels/flower heads need to be isolated (by a distance of at least 500 feet), or isolated by bagging. Because the pollen is so fine, corn tassel bags should be used. As long as the bags containing the tassels are jostled around now and then, either by the wind or by being shaken, the pollen will be sufficiently transferred from the male flowers to the female flowers.
The tassel bags should be left on the amaranth flower tassels/heads until the seeds are fully mature. Amaranth seeds mature at different rates along the stalk, from the bottom to the tip. To produce the most viable, pure seed, you can harvest the mature seed by shaking it out each day as the seed head matures.