Brilliant (Dianthus deltoides 'Brilliant') - red flowers, illustrated plant cardIllustration

Brilliant

Dianthus deltoides 'Brilliant'

Brilliant blooms from May through July.

Bloom calendar
Bloom time
May–Jul
not yet checked
Hardiness
Zones 3–9
not yet checked
Sun
Full sun
not yet checked
Water
Low water
not yet checked
Mature size
8 in × 14 in
not yet checked
Type
Perennial
house classification

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

Growing Brilliant

Plant it in full sun. It prefers low water. It is hardy in USDA zones 3–9. Expect it to reach about 8 in tall and 14 in wide at maturity, in roughly 2 years (not yet checked).

Verification
What this means

Written with AI assistance and not yet checked plant by plant against recorded sources, so treat every fact above as a starting point. Its scientific name was checked against botanical registries, an audit keeps its values consistent with the rest of the library, and a July 2026 review re-read the main facts of every plant then in the library against horticultural authorities without recording a source for each, which is why none of that counts as checked here. The source-by-source check is working through the whole library in the open, and a checked plant says so in this row.

When to plant Brilliant

Plant Brilliant 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 6, the middle of its hardy zones 3 to 9, spring means March to May and fall means August or September. Once settled, it blooms from May to July.

Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.

How big does Brilliant get?

Illustration of Brilliant drawn to scale beside an adult8 intall5 ft 7 inan adult14 inwide
About 8 in tall and 14 in wide at maturity: shin-high beside an adult.

See Brilliant 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 Brilliant

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

Space Brilliant about 14 in apart, center to center, so each plant has room to reach its full width.

Plant them
14 in apart
Per 10 sq ft
about 7
4 by 8 ft bed
about 18

Add Brilliant to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.

Good to know about Brilliant

Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.

Safety

Mildly toxic to dogs and cats: an unknown irritant causes mild stomach upset, and the leaves' saponins can cause mild skin dermatitis in sensitive people. per ASPCA and NC State

The Dianthus group

One of 14 in the Dianthus 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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