The following information is from the CRC Passover Guide

Amaranth and Quinoa

Are amaranth and quinoa kitnios?

Amaranth and quinoa are seeds which are similar enough to wheat and barley that they theoretically would be kitnios, and in fact some Poskim do treat them as such. However, Rav Schwartz accepts Iggeros Moshe’s (OC III:63) position that foods which were not consumed by Jews at the time the minhag of kitnios began are not forbidden on Pesach. Therefore, because when the minhag began (3-4 centuries ago) no Jews lived in the South American and Far Eastern countries where these grains grew, amaranth and quinoa are not considered kitnios and may be consumed on Pesach if one can be certain that no chametz-grains are mixed in.

This last caveat poses a particular concern for amaranth and quinoa, as these small seeds are often packaged on the same equipment as other small grains such as wheat, barley and oats, which means that they can only be used after being carefully checked that no chametz grains are mixed in. In practice, most consumers are not familiar enough with the difference between one grain and the next to be able to perform this check, and as a result they cannot use them for Pesach.

This year, we were once again able to confirm that the whole grain quinoa sold under the Ancient Harvest and Trader Joe brand names, and bearing the KOAOA/Half- Moon K kosher certification, are produced in plants which do not package chametz grains, and are therefore suitable for Pesach use. [This does not apply to the quinoa flour or flakes]. It is worth verifying this information before each Pesach to make sure the information remains accurate.

 

Information on Quinoa is also available from the Star-K