Delphinium

Delphinium detest heavy clay and are happiest in slightly alkaline soil.  Water regularly and apply granular lime once a year. 

During growing season, often add composted cow manure or 5-10-10 fertilizer.
Pinch out every flower stalk to devote the plant's energy  to build a larger, stronger crown.

The next year allow one stalk to grow, the following year - two and so forth.
Delphiniums are prone to fungus diseases, often soilborne.  Be vigilante about cleaning up dead foliage and replace mulch at least once a year.  If you follow these simple tips you too can enjoy the beauty of fully bloom Delphinium in your garden.