When I'm looking through this thread most of the mentioned plants are yellow - more or less. So I'd like to ask another question:
What are your earliest NON-yellow cultivars?
Mine are the following - all start usually around end of May/beginning of June:
Before, Early Alibi, Early Days, Flying Early, In Strawberry Time, Taffeta Mist, Pixie Parasol, Tigereye Spider, Tutankhamun, Vernal Tutone, When Robins Sing
