Color Spires Crystal Blue Salvia (Salvia × sylvestris 'Crystal Blue') - blue flowers, illustrated plant cardIllustration

Color Spires Crystal Blue Salvia

Salvia × sylvestris 'Crystal Blue'

Also called crystal blue sage

Color Spires Crystal Blue Salvia blooms from May through June.

Bloom calendar
Bloom time
May–Jun
checked
Hardiness
Zones 3–8
checked
Sun
Full sun
checked
Water
Moderate water
checked
Mature size
1.5 ft × 2.5 ft
checked
Type
Perennial
house classification

Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.

Growing Color Spires Crystal Blue Salvia

Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–8. Expect it to reach about 1.5 ft tall and 2.5 ft wide at maturity, in roughly 2 years (a house reading).

Pets

Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.

No toxicity note is on file for Color Spires Crystal Blue Salvia. That is not a clearance: check its safety for people and pets before planting.

Verification
What was checked

Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.

See the 8 sources it was checked against

When to plant Color Spires Crystal Blue Salvia

Plant Color Spires Crystal Blue Salvia in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 5, the middle of its hardy zones 3 to 8, spring means April to June and fall means August or September. Once settled, it blooms from May to June.

Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.

How big does Color Spires Crystal Blue Salvia get?

Illustration of Color Spires Crystal Blue Salvia drawn to scale beside an adult1.5 fttall5 ft 7 inan adult2.5 ftwide
About 1.5 ft tall and 2.5 ft wide at maturity: knee-high beside an adult.

See Color Spires Crystal Blue Salvia in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.

How far apart to plant Color Spires Crystal Blue Salvia

Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.

Space Color Spires Crystal Blue Salvia about 2.5 ft apart, center to center, so each plant has room to reach its full width.

Plant them
2.5 ft apart
Per 10 sq ft
about 2
4 by 8 ft bed
about 3

Add Color Spires Crystal Blue Salvia to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.

Where these facts come from

Color Spires Crystal Blue Salvia's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 18, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.

  • Walters Gardensbreeder and introducer, Michiganheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
  • promessedefleurs.comPromesse de Fleurs (French selling nursery)height, spread, water, bloom months and color and trait tags
  • RHSRoyal Horticultural Societyheight, spread, sun, water and bloom months and color
  • Plant Addictsqueue storeheight, spread, hardiness zones, sun and water
  • Chicago Botanic GardenPlant Evaluation Notes 52 (2025), Table 1, printed page 10height, spread and bloom months and color
  • Proven Winnerslicensed brandwater, bloom months and color and trait tags
  • active.inspection.gc.caCanadian Food Inspection Agency, Plant Breeders Rightsbloom months and color and trait tags
  • luriegarden.orgLurie Garden (Chicago, Illinois)height and spread

How the checking works, and what each standard covers, is on the verified plants page.

The Salvia group

One of 15 in the Salvia group. Same genus, similar care.

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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.

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