delphiniums

Let’s state the facts up front: Delphiniums are finicky flowers, and even for gardeners with the perfect climate and soil, they are short-lived perennials. Most plants decline rapidly after the third season of growth.

Now, let’s sweep aside those minor inconveniences and get these blue beauties into our gardens. No other perennial flower offers the range of royal, midnight, and sky blue hues combined with the drama of a six-foot flower spike. Delphiniums also grow in complementary white, pink, and lavender tones, sometimes with contrasting black or white centers.

Genus Delphinium, Family Ranunculaceae

Common Name:

Larkspur

Zone:

Hardy in zones 3-7, but performs poorly in areas with hot summers.

Size:

2-6 feet, depending on the variety

Exposure:

Full sun, or partial shade with morning sun in hot areas.

Bloom Period:

Early summer

Delphiniums demand moist soil, but they will rot in heavy clay with poor drainage. If you have problems with clay soil, it’s better to build a raised garden bed for the delphinium planting site. Even with staking, delphiniums don’t like to be whipped around by high winds, so place them close to the house or a privacy fence for protection.

Delphiniums are one of the perennials that thrive in alkaline soil, so if your pH falls below 6.5, broadcast some lime in the planting area.

Like many garden ornamental plants, delphiniums are susceptible to aphids, slugs, powdery mildew, and rust. A bacterial disease called “blacks,” sometimes mistaken as bacterial black spot, is actually a manifestation of cyclamen mites. These mites are invisible to the naked eye and resist treatment, so gardeners should remove affected plants.