Sweet alyssum Lobularia maritima
Sweet alyssum (Lobularia maritima) is an annual flowering plant in the Brassicaceae family, native to Mediterranean region and the Canary Islands. It grows 8–20 cm (3–8 in) tall and 20–35 cm (8–14 in) wide, wants full sun and moderate water, and is hardy to about -5 °C (23 °F). Space plants about 20 cm (8 in) apart.
Plan Sweet alyssum in your garden →
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Sweet alyssum at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Brassicaceae |
| Mature height | 8–20 cm (3–8 in) |
| Mature spread | 20–35 cm (8–14 in) |
| Spacing | 20 cm (8 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance none |
| Soil pH | 6–8 |
| Cold hardiness | About -5 °C (23 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 28 °C (82 °F) |
| Flowering | about 6–9 weeks after planting, for 13–21 weeks |
| Days to maturity | About 70 days from planting |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Yes: flowers |
| Native to | Mediterranean region and the Canary Islands |
| Common in gardens of | 🇺🇸 United States, 🇬🇧 United Kingdom |
Is Sweet alyssum toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
ASPCA lists sweet alyssum as non-toxic to dogs, cats and horses.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Sweet alyssum
Good neighbours
- good With Rhubarb: Traditional lore says rhubarb planted near brassicas helps against clubroot and pests; the evidence is weak and not confirmed by trials. Evidence D
- good With Nasturtium: Nasturtiums act as a trap crop for cabbage white butterflies and blackfly, drawing some pressure away from brassicas. Evidence C
Questions about Sweet alyssum
- How far apart should I plant Sweet alyssum?
- About 20 cm (8 in) apart, centre to centre. A mature plant spreads 20–35 cm (8–14 in).
- Does Sweet alyssum need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Sweet alyssum need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is Sweet alyssum?
- It tolerates about -5 °C (23 °F) once established, roughly USDA zone 9. As an annual it is usually planted out after the last frost.
- When does Sweet alyssum flower?
- About 6–9 weeks after planting, for 13–21 weeks.
- Is Sweet alyssum poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. ASPCA lists sweet alyssum as non-toxic to dogs, cats and horses.
- What grows well with Sweet alyssum?
- Traditional lore says rhubarb planted near brassicas helps against clubroot and pests; the evidence is weak and not confirmed by trials. Nasturtiums act as a trap crop for cabbage white butterflies and blackfly, drawing some pressure away from brassicas.
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- RHS Plant Finder, Royal Horticultural Society
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
Notes and assumptions
- Typical garden-form values; cultivars and local conditions differ.
- Short-lived perennial in mild climates, grown as an annual elsewhere; bloom slows in midsummer heat, and shearing renews it.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Broccoli Brassica oleracea var. italica
- Cauliflower Brassica oleracea var. botrytis
- Cabbage Brassica oleracea var. capitata
- Kale Brassica oleracea var. sabellica
- Radish Raphanus sativus
- Bok choy Brassica rapa subsp. chinensis
- Brussels sprout Brassica oleracea var. gemmifera
- Kohlrabi Brassica oleracea var. gongylodes