From what I've read, you can tell by the color of the epicotyl (part of the baby stem, just above the root). In red clivias, it will be pigmented -- in yellow ones, it will be green.

Disclaimer: I am NOT an expert, this is just what I've read!

ok! thanks! then it is some truth in what i´ve heard ;)

Hi,

For the most part, yellow Clivia seedings will produce green bases (no pigment), since they lack the final steps to produce the red pigments. There are very few exceptions, and none of those are commercially available in the USA. Orange and red Clivias will produce a colored base. You can usually distinguish while the first leaf is elongating. Therefore if you are trying to grow yellows from a mixed batch of seeds, you can eliminate all those with colored bases. Also, the color of the base does not accurately reflect the depth of color in the future flower. Hopefully this helps.

Craig
Sacramento, CA

Thanks Craig! For your nice answer!