Candle Larkspur Blue | Blue-Giant Spikes That Steal The Show

Candle Larkspur Blue is a name for blue-flowered varieties of Delphinium elatum, specifically the tall, spire-shaped perennial known for its deep blue flower spikes that rise like candles in the garden.

Nothing stops a gardener mid-stride like a five-foot tower of blue blooms that looks carved from sky. That’s the draw of Candle Larkspur Blue. The name covers a handful of Delphinium elatum cultivars bred for their dense, upright flower stalks and intense blue coloring. They bloom in late spring and early summer, often rebloom later in the fall with a trim, and fill a vertical gap few other perennials touch. Below, the top cultivars, the exact steps to keep them standing, and the one requirement that trips up even experienced growers.

The term “Candle Larkspur Blue” isn’t a single patented plant you will find on a tag. It is the gardeners’ shorthand for blue Delphinium elatum varieties—tall, hardy perennials that grow spires of blue flowers with white or dark centers. The most common cultivars carrying this description are ‘Guardian Blue’ (also sold as Blue Guardian Larkspur), ‘Blue Lace’, ‘Aurora Blue’, and ‘Blue Candle’. They are native to alpine Europe, adapted to cool summers, and perform best in USDA Hardiness Zones 3 through 8.

Which Cultivar Matches What You Want?

The four main blue varieties share the same basic care but differ in height, bloom window, and the exact shade of blue. Choose by the space and the color depth you need in the garden.

‘Guardian Blue’ tops out around 30–40 inches with deep blue flowers and a white “bee” center. It is the most common commercial container plant and offers a secondary fall bloom if spent stalks are cut back. ‘Blue Lace’ pushes taller—5 to 6 feet—with sky-blue blossoms. Its New Millennium Series parentage gives it better cold tolerance and a longer early-summer-through-fall bloom period. ‘Aurora Blue’ stays compact at 3 to 4 feet with vibrant sky-blue spikes, suited for smaller borders. ‘Blue Candle’ matches the compact height range and is notable for its deep blue spikes and a longer zone range (3–9), making it work in warmer climates that usually kill tall delphiniums.

Table: Top Candle Larkspur Blue Cultivars Compared

Prices for a 4-inch pot of ‘Blue Candle’ run about $12.99, and a 3-gallon ‘Guardian Blue’ hovers near $24.99. Retailers vary by season and region, so check local garden centers or the grower’s online shop before committing.

Where To Plant Candle Larkspur Blue

Full sun is non-negotiable—5 hours minimum. Morning sun is best because it dries the leaves early and reduces mildew risk. In zones 7 and above, afternoon shade is necessary; without it, the leaves scorch by August and the plant declines fast. The soil must be moist but fast-draining, rich in organic matter. Soggy ground is the number-one killer—crown rot takes a plant down in days.

Set the crown slightly above the soil line. Burying it even a half-inch deep invites rot. Space plants 24 to 36 inches apart—while they spread only 2 to 3 feet wide, tight spacing blocks air circulation and leads to powdery mildew. Pick a spot sheltered from strong wind, or commit to staking. A 6-foot blue spike in a summer thunderstorm flops without support.

Planting And Initial Care Sequence

Transplant container-grown plants in spring after the last frost. Follow this order:

• Dig a hole twice the width of the container and the same depth.
• Mix a handful of compost into the backfill soil.
• Place the plant with the crown an inch above the surrounding soil line.
• Backfill gently, water at the root zone—not overhead—until settled.
• Add a 2-inch layer of organic mulch around the base, keeping it off the crown.

Water moderately through the first growing season. The goal is consistent moisture—about 1 inch per week including rainfall—without waterlogged soil. After the first year, reduce watering frequency; established plants handle short dry spells.

Pruning, Staking, And Reblooming

Prune in spring when the stems reach 12 to 18 inches tall. Cut up to two-thirds of each stem just below a flowering bud—this encourages bushier growth and more flower spikes. When the main bloom finishes in July, cut the spent flower stalk to the base. A second, weaker flush of blooms will appear in early fall.

Support the flower stalks early—do not wait until the spike leans. Push a bamboo stake or a metal ring in at planting time, not when the stem is already bending. The tall varieties—’Blue Lace’ especially—need this to survive wind and heavy rain.

Every three years, dig the clump up after the fall bloom, discard the old center, and replant young shoots from the edge of the clump. This keeps the plant vigorous and prevents the short-lived perennial from fading after its natural 2-to-3-year lifespan. Mulch heavily in fall; the roots survive winter in the ground in zones as cold as 3.

Six Mistakes That Break Candle Larkspur Blue

These failures are predictable and preventable. Most growers run into one of them in the first season:

• Overwatering or poor drainage. The top cause of death. Crown rot sets in within a week of soggy roots. Plant high, water deep but infrequent, and let the top inch of soil dry between watering.
• No staking. Spikes up to 6 feet don’t stand upright in summer storms. Stake early or lose the flower spike to a single gust.
• Planting too deep. The crown must sit above the soil. Buried crowns rot. This is the second-most-common death sentence.
• Too much nitrogen. Heavy fertilizer makes stems soft and floppy. Use a balanced 10-10-10 at planting and skip midsummer feeding.
• Tight spacing. Crowded plants trap humidity and breed powdery mildew. Give each plant 24 to 36 inches of breathing room.
• Ignoring shade needs in hot zones. In zones 7 and 8, full afternoon sun burns the leaves to a crisp. Morning sun plus afternoon shade is the survival formula.

Table: Candle Larkspur Blue Safety And Longevity

Its toxicity makes this a high-risk choice for households with free-roaming pets or young children. Plant away from grazing areas. The trade-off is a vertical blue structure in the garden that few other perennials match for sheer impact. If you can meet the sun, drainage, and staking requirements, and you have a safe place for it, Candle Larkspur Blue delivers its blue spires like clockwork from late spring through early fall.