Bryan McAllister’s personal reference notebook
July 30, 2026Short & citedBlog
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Field Notes • Plant

Delphinium

Delphinium is a genus of flowering plants in the buttercup family (Ranunculaceae), commonly known as larkspur.

Updated July 30, 20261 min readCited sources

Delphinium is a genus of flowering plants in the buttercup family, also known as larkspur. It includes annual, biennial, and perennial species grown for tall, showy flower spikes.

What it is

Delphinium is a genus in the buttercup family (Ranunculaceae) with about 300 species native mainly to the Northern Hemisphere. The plants are known for tall flowering spikes and deeply lobed leaves. Most garden delphiniums are grown for their tall spikes of blue, purple, pink, red, or white flowers.

Why it matters

Delphiniums are widely grown in gardens, especially in cooler regions like Canada, where they provide early-summer colour. They prefer fertile, moist but well-drained soil and full sun or partial shade. Many cultivated delphiniums are short-lived perennials, lasting only a few years, and some gardeners grow them as annuals in warmer climates.

Key details

Delphiniums typically bloom in late spring to early summer, often in June and July. All parts of the plant are toxic to humans and animals if ingested, so care is needed in gardens with pets or livestock. Flower colours include blue, purple, white, pink, red, yellow, and two-coloured forms.

In short

  • Genus of flowering plants in the buttercup family, also called larkspur.
  • Grown for tall, showy flower spikes in various colours.
  • All parts are toxic to humans and animals.
  • Often short-lived perennials in gardens.
Canadian angle

Delphiniums are widely grown in Canadian gardens, especially in cooler regions where they can perform well as border perennials and provide early-summer colour.[9][10]

Quick questions

What is delphinium?
Delphinium is a genus of flowering plants in the buttercup family, also called larkspur. It includes annual, biennial, and perennial species grown for tall, showy flower spikes.
Are delphiniums poisonous?
Yes. Delphiniums are toxic to humans and animals if ingested, and all parts of the plant are considered poisonous.
When do delphiniums bloom?
They usually bloom in late spring or early summer, often in June and July. Some varieties may bloom again later in summer or early autumn.

Sources

  1. Wikipedia — https://en.wikipedia.org/wiki/Delphinium
    Supports: Genus description; family; approximate species count; native range; toxicity
  2. NC State Extension Plant Toolbox — https://plants.ces.ncsu.edu/plants/delphinium/
    Supports: Species range; annual/biennial/perennial forms; family; toxicity; name origin
  3. University of Saskatchewan — https://gardening.usask.ca/articles-and-lists/articles-plant-descriptions/perennials/delphinium.php
    Supports: Bloom time; flower colours; native range; toxicity
  4. Royal Horticultural Society — https://www.rhs.org.uk/plants/delphinium/perennial/growing-guide
    Supports: Growing guidance; perennial habit; bloom characteristics
  5. University of Nebraska–Lincoln — https://lancaster.unl.edu/delphiniums-beautiful-garden-flower/
    Supports: Short-lived perennial habit; toxicity
  6. Plants & Flowers Foundation Holland — https://www.plantsandflowersfoundationholland.org/en/flowerguide/delphinium/
    Supports: Flower colours; bloom period; toxicity
  7. Royal Horticultural Society — https://www.rhs.org.uk/plants/delphinium
    Supports: Flower colours and general plant description