Bloom Season.  Our descriptions are based on registration information supplied by hybridizers. The season codes (E for early, M for mid-season and L for late) give a general sense for when the bloom season begins, but the codes are usually based on where the hybridizer created the plant.  Many of them live in the south, so, E (early) may be late April in Florida , but late May here in Virginia.  We’ve also learned from experience that micro-climates and other conditions in different parts of the garden will influence bloom seasons. Thus, some cultivars that are listed as M (mid season) or even L (late) may bloom before cultivars with earlier listings, depending on where they are in the garden.