Sweet Alyssum
Lobularia maritimaUSDA | Grow Zone
3-10Outdoors all year in zones 3 to 10. Anywhere colder, keep it as a houseplant. Protect it below 32°F.
- Light
- Full sun to partial shade
- Water
- When top inch is dry
- Humidity
- 40-60%
- Temperature
- 60-75°F (15-24°C)
- Difficulty
- Beginner
- Growth
- Moderate
- Mature size
- 6-12 in tall, 12-24 in wide
Sweet Alyssum (Lobularia maritima) is a charming annual known for its fragrant, delicate flowers. Originating from coastal regions, it thrives in gardens and containers, attracting pollinators and adding beauty to any landscape.
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Ideal temperature
60-75°F is where it grows fastest. Below 32°F cold damage starts.
Spacing and harvest
- Mature size
- 6-12 in tall, 12-24 in wide
- Plant apart
- 12-24 in
- Frost
- Half hardy: light frost only
Everything it needs
9 essentials at a glance
Watering
Sweet Alyssum prefers consistently moist soil but can tolerate short periods of dryness.
Water when the top inch of soil feels dry, typically every 3-5 days in warmer months. During hot weather, increase frequency as needed. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and browning of leaf edges.
Light
Sweet Alyssum thrives in full sun to partial shade, ideally receiving at least 6 hours of direct sunlight daily.
In hotter climates, some afternoon shade can help prevent heat stress. It can tolerate light shade but may produce fewer flowers.
Soil
This plant prefers well-draining soil with a pH range of 6.0 to 7.0.
A mix of loamy soil and compost is ideal, providing nutrients while ensuring good drainage. Avoid heavy clay soils that retain water.
Humidity
Sweet Alyssum enjoys moderate humidity levels, around 40-60%.
To increase humidity, mist the plant or place a humidity tray nearby. Signs of low humidity stress include browning leaf tips and wilting.
Temperature
Ideal temperatures for Sweet Alyssum range from 60-75°F (15-24°C).
It is hardy in USDA zones 3-10, tolerating light frost but not extreme heat. In summer, ensure it has adequate moisture to cope with higher temperatures.
Fertilizing
Use a balanced, water-soluble fertilizer with an NPK ratio of 10-10-10 every 4-6 weeks during the growing season.
Reduce feeding in late fall and winter. Signs of nutrient deficiency include yellowing leaves and poor growth.
Pruning
Prune Sweet Alyssum in early spring to encourage bushier growth and remove any dead or damaged stems.
Use sharp, clean scissors or pruning shears. Deadheading spent flowers regularly can promote continuous blooming.
Repotting
Repot Sweet Alyssum every 1-2 years or when it becomes root-bound.
Choose a pot that is 1-2 inches larger in diameter. Signs it needs repotting include roots growing out of the drainage holes and stunted growth. Gently remove the plant from its pot, loosen the roots, and place it in fresh potting mix.
Propagation
Sweet Alyssum can be propagated through seeds or cuttings.
For seeds, sow them in spring after the last frost, lightly covering them with soil. For cuttings, take 4-6 inch stem cuttings in early summer, remove lower leaves, and place in moist potting mix until roots develop.
When it's unhappy
Yellow leaves
Why it happens
Often caused by over-watering or nutrient deficiency.
How to fix it
Adjust watering schedule and check soil nutrients, applying fertilizer if needed.
Wilting
Why it happens
Typically due to under-watering or extreme heat.
How to fix it
Increase watering frequency and provide shade during the hottest part of the day.
Root rot
Why it happens
Caused by overly wet soil and poor drainage.
How to fix it
Ensure proper drainage and reduce watering frequency. If severe, repot into fresh, dry soil.
Pest infestations (aphids, spider mites)
Why it happens
Common pests attracted to stressed plants.
How to fix it
Inspect regularly, and treat with insecticidal soap or neem oil as needed.
Poor flowering
Why it happens
Can result from insufficient light or nutrient deficiency.
How to fix it
Ensure the plant receives adequate sunlight and consider fertilizing to boost blooms.
Care through the year
Spring
In spring, prune back any dead stems and fertilize to encourage new growth. Ensure the plant is well-watered as it starts to bloom.
Summer
During summer, monitor for pests and ensure consistent watering, especially in hot weather. Deadhead regularly to promote more flowers.
Fall
In fall, reduce watering as temperatures drop and prepare the plant for cooler weather. Consider bringing potted plants indoors if frost is expected.
Winter
In winter, Sweet Alyssum can survive light frost but may need protection from extreme cold. Reduce watering and avoid fertilizing during dormancy.
Toxicity & Safety
Sweet Alyssum is non-toxic to pets and children, making it a safe choice for gardens. No known toxic effects are associated with ingestion.
Good to know
How often should I water my Sweet Alyssum?
Water Sweet Alyssum when the top inch of soil feels dry, typically every 3-5 days in warm weather. Adjust frequency based on humidity and temperature.
Why are my Sweet Alyssum leaves turning yellow?
Yellow leaves can indicate over-watering or a lack of nutrients. Check the soil moisture and consider fertilizing if necessary.
Can Sweet Alyssum tolerate heat?
While Sweet Alyssum prefers moderate temperatures, it can tolerate heat if kept well-watered and provided with some afternoon shade.
How do I propagate Sweet Alyssum?
You can propagate Sweet Alyssum from seeds or stem cuttings. Sow seeds in spring or take cuttings in early summer for best results.
What should I do if my Sweet Alyssum is wilting?
Wilting may be a sign of under-watering or heat stress. Increase watering and provide some shade during the hottest parts of the day.
Is Sweet Alyssum safe for pets?
Yes, Sweet Alyssum is non-toxic to both pets and children, making it a great choice for family gardens.
When should I prune my Sweet Alyssum?
Prune Sweet Alyssum in early spring to promote bushier growth and remove dead stems. Regular deadheading will encourage continuous blooming.
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