Does it need staking?

Yes, the tall flower spikes often require support to prevent them from falling over in the wind.

Can I grow it in a pot?

It grows well in containers if they are deep enough to accommodate the taproot.

Plant guide

Rocket larkspur.

Consolida ajacis

Pronounced kon-SOL-ih-duh ah-JAY-sis

Also known as Consolida ajacis, Larkspur, Rocket larkspur, doubtful knight's-spur, eastern larkspur

Delphinium ajacis — Photo by Rita Wright (CC BY) via gbif

Rocket larkspur is a charming annual that brings tall, colorful spikes to your garden. It is a classic cottage garden favorite that blooms beautifully in late spring and early summer. You will love how easily it adds vertical interest to your flower beds.

Another photo of Rocket larkspur — Photo by Adrien Cozannet (CC BY) via iNaturalist

At a glance

Care level: Moderate
Plant type: Annual
Light: Full sun
Indoor light: Direct sun
Water: Every 3 to 7 days
Mature size: 2 to 4 feet
Growth rate: Fast
Hardiness: USDA 2 to 11
Bloom time: Late spring to mid summer

Care

Plant these in a spot with plenty of sun and well draining soil. Keep an eye out for powdery mildew on the leaves during humid weather. Deadheading spent blooms can encourage a second flush of flowers later in the season.

Watering: Keep the soil consistently moist but never waterlogged.
Feeding: Apply a balanced liquid fertilizer once a month during the growing season.
Pruning: Remove faded flower spikes to tidy the plant and promote new growth.
Repotting: As an annual, this plant completes its life cycle in one season and does not require repotting.
Soil: Well draining, fertile soil
Soil pH: 6.0 to 7.5
Temperature: -10 to 30°C
Humidity: 40 to 60%
Drought tolerance: Moderate
Lifespan: Annual, one season.
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes.
Stunted growth despite regular feeding.

Safety

People: The plant contains diterpene alkaloids that are poisonous to humans and pets if eaten.
Pets: This plant is toxic to cats and dogs if ingested.
Children: Keep this plant away from children as all parts are highly toxic if ingested.
Contact allergens: Handling the foliage can cause skin irritation or dermatitis in sensitive individuals.
Airborne allergens: The pollen is generally not considered a major allergen.
Edibility: All parts of this plant are toxic if ingested and can cause severe digestive distress.

How to identify it

Tall spikes of colorful flowers
Finely divided, fern like foliage
Spurred petals on each bloom
Upright and slender growth habit

Height: 0.3 to 1.2m
Spread: 0.15 to 0.3m
Leaves: green, deciduous
Flowers: blue, purple, pink, white, 2 to 4cm
Fruit: brown, Late summer

Problems to watch for

Powdery MildewCommon
Slugs and SnailsCommon
AphidsUncommon
Leaf MinersUncommon
Root RotUncommon
Damping OffRare

By symptom

Plant problems by symptom

Check your rocket larkspur from a photo

Pocket Botanist looks at a photo of your plant and tells you what's wrong and what to try first.

Growing it

Propagation: seed
When to plant: spring, autumn
Overwintering: As an annual, it will die back completely after setting seed. You can collect the seeds in late summer to sow again the following spring.
In containers: It grows well in pots at least 30 cm deep to allow for its taproot development.

Direct Sowing

1. Prepare a sunny spot with well draining soil.
2. Sow seeds directly in the ground in early spring or autumn.
3. Cover with about 0.5 cm of soil, as the seeds need darkness to germinate.
4. Keep the area moist until seedlings emerge.
5. Thin the seedlings to 20 cm apart.

Plant these in groups to provide mutual support against wind and to create a dense visual impact.

Grows well with

Foxglove · They share similar soil requirements and provide a beautiful vertical contrast.
Peony · Peonies provide a lush backdrop for the slender spikes of the larkspur.

Similar species

Perennial Larkspur · This is a long lived perennial relative with much larger flower spikes.

Science

Family: Ranunculaceae
Genus: Delphinium
Order: Ranunculales
Class: Magnoliopsida
Native range: Southern Europe and the Mediterranean region.
Conservation: Not of conservation concern as it is widely cultivated and naturalized.

It thrives in open, sunny areas with well drained soil and often colonizes disturbed ground.

Value to wildlife: nectar source
Pollinators: bees, butterflies
Uses: cottage gardens, cut flowers, border planting

Through the year

JFMAMJJASOND

Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 5/9
Moisture: 5/9
Nutrients: 6/9

Taxonomy resolved against GBIF.

Questions people ask

Does it need staking?: Yes, the tall flower spikes often require support to prevent them from falling over in the wind.
Can I grow it in a pot?: It grows well in containers if they are deep enough to accommodate the taproot.

Where the name comes from

The name Delphinium comes from the Greek word delphis, meaning dolphin, referring to the shape of the flower bud. The species name ajacis refers to the Greek hero Ajax.

Good to know

It is often called Rocket Larkspur because of its tall, upright flower spikes.
The seeds are best sown directly in the garden where they are to grow.
It is an annual plant that completes its life cycle in one season.

Also in

Keep your rocket larkspur growing

This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.

Get the app

This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.