I have left my star gazer lilies to just reseed themselves, but last year they came up yellow instead of their bright pink color. Is it my soil? Or do I need to dig them up and sort out the bulbs?
I'ver never heard of lilies being dependant on soil for color like hydrangia's are.
Many plants offspring don't match the parents colors, especially if they are hybrids.
No its not to soil some times it happen even when i get some rose plants they say it is pink color rose but when they grow the color will will be different,,,, but i do no whats the actual reason...
Hybrid roses are often grafted to different tougher root stock. When winter kills off the top, the new growth comes from the root stock, typically red dawns. That big knot on a bare root rose is the union bud (I believe that's what it's called). In northern climates, that bud should be planted 6 to 8 inches below the ground for a better than snowball's chance of it coming up in the original color. Close to the house with some bush in front of it for shelter, I'm having pretty good luck with them coming back every year.
As for the stargazers, I have quite a few in my brutally dry yard and they come back the same beautiful pink every year. My only thought is, if they were bought in rhizome/bulb state, maybe they were mislabeled. If the yellow are offspring, possibly the parents are hybrid in which case, any color can come up (called "sports" I think). Sorry, I don't know more about them.