Royal Eventide is a very interesting plant. I've just been reading through
@Seedfork Larry's review and comments about it. I see that the database entry has been updated to describe the plant as a double, which I am sure it is, although it is a unique-looking one.
First of all I'll say that I have not tried any crosses with Royal Eventide, so I can't comment on its fertility or difficulty of setting pods, etc. If I do try to use it, I'll update.
I received a nice 8-to-10-fan clump of Royal Eventide from Arrasmith Farm in the fall of 2021, so I've had the plant for two bloom seasons. Mine has not yet taken off like Larry's. That may be because I moved it after its first season. It was very crowded in its bed, and I just moved it forward a few inches. A move is a move, though, so I'm not sure the plant has had a chance to fully settle in, and it hasn't reached its registered height yet. Still, I've been very pleased with the plant.
I wanted Royal Eventide because of its rust resistance and its extreme earliness. Its reputation for both qualities is fully deserved. It has never shown rust in my garden, and both seasons it has been the second of all my cultivars to bloom, right after Bitsy, who retains the top spot.
The blooms are interesting rather than beautiful. The color is mauve-purple with white stripes on the petals. Sometimes it looks like a bitone. It's not consistently double--even when it is, the amount of extra tissue varies. Both seasons its first couple of blooms have been singles. At what I would call its most characteristic, it almost has a scrambled-eggs effect:
Here's another shot from its first season showing a single and a double bloom:
You can see the healthy dark-green foliage described by Larry above. (The whitish spots are Liquid Fence.)
This season Royal Eventide showed similar performance but surprised me with a very late rebloom in October. The plant blooms so early that I tend to forget about it later. All the reblooms were singles:
Royal Eventide overall has been a good performer, and I will keep it.