Larkspur is a member of the Delphinium family and though native to Europe, it grows well in North America. The plant is poisonous if eaten by cattle but fortunately only mildly toxic to domestic pets and people. 

Its colors are shades of blue/purple, white, and pink, and its tall upright habit and ferny, lacy foliage is good in combination with other garden plants. Larkspur likes well drained soil in full sun and is a good cut flower. 

In my midwestern garden I cannot grow perennial delphiniums or perennial larkspur. So, I buy packets of annual larkspur seeds and just sprinkle them in my beds (unmulched, as mulch often has a seed germination deterrent) in early spring. I am rewarded with pretty flowers that meld well with many of my perennials. For example, I have a bed of white iris, and the larkspur grows up and blooms before the iris have finished their show. Larkspur also blend nicely with daylilies because of their height. Larkspur seeds germinate best between 40-50F in zones 4-7. 

I would not be without my annual larkspur, which I have enjoyed year after year and some often self-seed and return, but in order to be sure, I always buy some seeds. I don't want to risk a year without it!

 Note: Larkspur grows well in zones 4-7 but needs protection to self-sow below zone 5. Field larkspur grows wild in cornfields throughout Europe.