FlowerAlyssum
Royal Carpet Alyssum
Ground Cover
Royal Carpet Alyssum is a beloved All-America Selections winner from 1953 that transforms garden borders into a fragrant, jewel-toned tapestry. This vigorous annual reaches just 4 to 6 inches tall but spreads 4 to 8 inches wide, creating a dense mound of violet-purple, magenta, and fuchsia blooms with a delightful honey-like scent. Hardy in zones 4 to 11 (though sources vary on the upper limit, with some reporting zone 4), it moves from seed to flowering in 56 to 63 days, making it one of the quickest performers for filling beds, window boxes, and hanging baskets with season-long color.
Photo © True Leaf Market
Growing Conditions
USDA Zone
4-4
Sunlight
Full Sun
Water
Moderate
Soil
Well-drained, Sandy To Loamy Soil; Tolerates Poor Soils
Preferred Temp60-75°F
Growth Stats
6 in
Height
8 in
Width
4 in
Spacing
63–63
Days to Harvest
PeriodAnnual
TypeForb/herb
Plant Profile
Sunlight
Full Sun
Water
Moderate
Zones
4-4
Size
6in H x 8in W
Growth
Annual
Care
Low
Hover over chart points for details
Highlights
This vintage favorite was named an AAS Bedding Plant Winner, a distinction it earned for its ability to deliver nonstop blooms with minimal fussing. The rich violet and magenta petals carry a genuine honey fragrance that intensifies on warm days, attracting pollinators and delighting anyone who brushes past it. Royal Carpet's low-growing, spreading habit makes it perfect for edging and gap-filling, and it blooms from early summer through frost without demanding deadheading.
Common Uses
Royal Carpet Alyssum excels in ornamental applications where its fragrant, low-growing mound is the main attraction. It's particularly valued for edging perennial beds, softening the hard lines of pathways, and cascading over the edges of containers and window boxes. The dense flower coverage and sweet scent make it an excellent choice for cutting gardens meant to bring fragrant blooms indoors, and its compact growth habit allows it to fill bare spots between taller plants without overwhelming neighboring flowers.
Growing Timeline
First Bloom
Early Spring
First Harvest
Not Applicable
Last Harvest
Not Applicable
Care Instructions
Start Indoors
Start seeds indoors 4 to 6 weeks before your last spring frost. Sow seeds on the surface of moist seed-starting mix—they need light to germinate—and keep the soil around 70°F. Seeds typically sprout within 7 to 10 days. Maintain consistent moisture and provide bright, indirect light once they emerge.
Transplant Outdoors
Transplant seedlings outdoors after your last spring frost date, once soil temperatures have warmed to at least 60°F. Harden off plants by gradually exposing them to outdoor conditions over 7 to 10 days. Space plants 4 inches apart in their final positions.
Direct Sow
Direct sow seeds outdoors after the last spring frost once soil has warmed. Scatter seeds where you want them to bloom, press lightly into the soil surface (do not cover), and keep the area consistently moist until germination occurs. Thin seedlings to 4 inches apart once they have true leaves.
Pruning
Royal Carpet Alyssum's mounding habit naturally creates a dense, compact shape that rarely requires pruning. However, if plants become leggy or sparse mid-season, pinching back the tips by an inch or so in early summer will encourage branching and fuller growth. Deadheading isn't necessary for continuous blooming, the plant flowers prolifically without it, but removing spent flower clusters occasionally can tidy the appearance if desired.
Growing Calendar
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Companion Planting
Ecology & Traits
Scientific Classification
Alyssum simplex Rudolphi
Family
Brassicaceae
Genus
Alyssum
Duration
Annual
Growth Habit
Spreading
Native Status
L48 (I)
History & Origin
“Royal Carpet Alyssum earned its All-America Selections award in 1953, a testament to its revolutionary impact on garden design at a time when breeders were perfecting compact, floriferous annuals for American home gardeners. The variety represents decades of selective breeding aimed at creating a true carpet-forming alyssum, one that would spread horizontally while remaining manageable in height, filling niches that taller varieties couldn't address. This heritage of commercial recognition and widespread adoption has made it a cornerstone variety in ornamental breeding.”