Time to sow in a cold frame:

Violas 
Lupins we’re sowing  Dwarf fairy pink
Aquilegia,  - carulea
Aconitum or monks hood or wolf’s bane
Hollyhocks creme de cassis
Eryngium 
Echinops
Verbascum  - I think they are like hollyhocks and lavateras seeds off outdoors now either direct sown or in pots in a coldframe.
Salvias 
Red Hot Pokers 
Hardy Geraniums
We have Wargrave Pink, and you can’t get rid of it! It is very invasive. But there are so many others! I quite fancy Orchid Blue and purple haze
Sow where they will grow
Poppies of all kinds
Ammi majus (Bishop's Weed))

Cornflowers
Poached Egg plant
Larkspur