I wonder if meiwa can be grown in zone 13. I still remember when I was a kid in my country (tropical region), I had never heard of the yellow kumquat fruits neither Nagami or Meiwa but a green round kumquat which has a very thin sour rind and sour pulp. I still remmeber that the pulp is orange and very sour, rind taste between bitter and sweet with spiciness and strong citrus fragrance. I think people picked them green on purpose just to preserve the sourness for a lime substitute.