French marigolds

mac12

Last year I sowed orange and yellow french marigold seeds all the yellow ones grew but only about 10 of the orange ones, last week I sowed both again on the the same day same compost everything the same and all the yellow are growing but nothing fro the orange. Why? 

Allotment Boy

I will be honest I do not really know but my best guess would  be it's to do with the vigour of the two cultivars. Perhaps the original is the yellow & in breeding the orange strain some of that vigour has been lost.  Someone on here will know for sure.