Lilies Stargazers?

Question

For the last two years I have grown Stargazer lilies.

They are still in the large tubs I first planted them.

This year for some unknown reason they have not only grown huge but one of them is pure white.They were always the same Stargazer colour. Also this white one has a very thick stem

Does anyone know why this is

Answer 1

  Stargazer is a hybrid of two other lilies with different characteristics.  One of your bulbs has reverted to the original lily which was white and had a thicker stem.

I think that is the logical answer

Cheers

Answer 2

Not really a lot I can add to Maranata's answer it is accurate.