Sweet alyssum
Lobularia maritima · Mustard family (Brassicaceae)
| Hardiness zones | 2 to 11 |
|---|---|
| Sun | full sun to part shade |
| Water | moderate |
| Life cycle | annual |
| Frost | Half-hardy: takes a light frost |
| Days to harvest | 42 to 56 days |
About Sweet alyssum
Sweet alyssum is a low, mat-forming annual covered in tiny, fragrant flowers from spring to frost where summers are cool. It is an excellent nectar plant for small beneficial insects like hover flies and tiny wasps.
Grown as an annual everywhere; NC State describes it as an annual or short-lived perennial and lists zones 5-9.
When to plant
Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.
- Start seeds indoors: 5 to 6 weeks before the last frost
- Set out plants: 1 to 2 weeks before the last frost
- Sow seeds outdoors: 2 to 4 weeks before the last frost
Days count from sowing to first flowers. Barely cover the seed, since light helps it sprout. It flowers best in cool weather and fades in summer heat; shear it back and it revives, or sow again in August for fall bloom.
Soil
Well-drained clay, loam or sandy soil; tolerates a wide pH range and short dry spells.
Plant in average, well-drained soil with medium moisture.
Feeding
Do not fertilize heavily: rich soil gives leaves instead of flowers.
Harvest
No harvest needed; when plants look ragged in summer heat, cut them back and they will revive as it cools.
Varieties (15)
| Variety | Type | Days | Notes |
|---|---|---|---|
| Snow Princess | Hybrid alyssum (L. maritima x L. canariensis) | Vigorous, spreading hybrid with fragrant white flowers from spring to frost; drapes well from baskets. | |
| Aphrodite series | Sweet alyssum (Lobularia maritima) | Compact, early-blooming seed series in apricot, salmon, lemon, red, white and purple. | |
| Clear Crystal series | Sweet alyssum (Lobularia maritima) | About 6 in tall and 12 in wide with large, fragrant flowers in white, lavender and purple shades. | |
| Easter Bonnet series | Sweet alyssum (Lobularia maritima) | Compact, early-flowering, 4-10 in tall, in deep pink, deep rose, violet and white. | |
| Frosty Night | Sweet alyssum (Lobularia maritima) | Small white flowers over variegated leaves. | |
| Giga White | Sweet alyssum (Lobularia maritima) | Large, fragrant white flowers; heat tolerant. | |
| Knight series | Sweet alyssum (Lobularia maritima) | Fragrant and long-blooming, with good heat tolerance. | |
| New Carpet of Snow | Sweet alyssum (Lobularia maritima) | Very low, 3-4 in tall and 8-10 in wide, with white flowers. | |
| Oriental Night | Sweet alyssum (Lobularia maritima) | About 4 in tall with deep violet-purple flowers. | |
| Pastel Carpet Mix | Sweet alyssum (Lobularia maritima) | Seed mix of pink, rose, lavender and cream. | |
| Princess series | Sweet alyssum (Lobularia maritima) | Heavy bloomer that handles both heat and cold. | |
| Rosie O'Day | Sweet alyssum (Lobularia maritima) | About 4 in tall with rose-pink flowers. | |
| Royal Carpet | Sweet alyssum (Lobularia maritima) | About 3 in tall and 10 in wide with violet flowers that fade to lavender. | |
| Snow Crystals | Sweet alyssum (Lobularia maritima) | Vigorous white alyssum with large flowers. | |
| Wonderland series | Sweet alyssum (Lobularia maritima) | Quick to bloom in many colors, with a shorter season. |
Good neighbors
Zucchini and summer squash, Winter squash and pumpkin
A Florida study found sweet alyssum planted with squash increased natural enemies of aphids and slightly raised yield (University of Minnesota Extension).
Pests to watch for
Imported cabbageworm, Bagrada bug, Diamondback moth
Diseases and problems
Rot in wet, crowded plantings
In the kitchen
Pets: Not toxic to dogs, cats or horses (ASPCA 'Alyssum' entry, listed as Alyssum spp.)
Sources
Photo: Photo: w0zny, CC BY-SA 4.0, via Wikimedia Commons (CC BY-SA 4.0). Photo resized for the web.
Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.