One of the most enduring garden annuals is sweet alyssum. This old-fashioned favorite is gaining new popularity as gardeners realize the benefits of this important companion plant. Learn how to grow alyssum with these 5 tips, add beauty and attract pollinators and beneficial insects to your garden.
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5 Tips for How to Grow Alyssum
1. Plant alyssum from seeds or transplants
Alyssum is very easy to start from seeds directly in the garden.
To plant alyssum from seeds outside:
- Lightly sprinkle a seed or two 6 inches apart.
- Press seeds lightly into the soil; do not bury them as they need light to germinate.
- Keep seeds moist (light mist) until they germinate.
- Seeds often pop up within 2-3 days in the right conditions.
- Once seedlings emerge and are 2-3 inches tall, thin to 6-12 inches apart (depending on variety).
To plant alyssum from transplant outside:
- Look for young compact transplants; overgrown transplants may not adapt as well to planting.
- Space plants 6 -12 inches apart depending on the variety.
- Do not let transplants dry out until they become established.
2. Choose the best location for planting alyssum
Alyssum is a low-lying spreading plant that is about 3-9 inches tall and 6-12 inches wide (depending on variety).
- Plant alyssum in a location that gets plenty of sunlight – at least 6 hours.
- Alyssum grows well in average soil, but it must be well-draining; it does not like wet feet.
- Alyssum is an excellent choice for growing in containers.
- Plant alyssum along the edges of containers — as an edge of beds; a ground cover; hanging baskets; interplanted in your garden beds; or in between rows in the garden.
3. Plant alyssum at the right time
Sweet alyssum is a cool-season flower that grows best in mild weather.
- In cold-winter areas, plant after all danger of frost has passed in the spring. Most varieties will bloom through fall.
- In mild winter areas, plant during the fall and winter for blooms until it gets hot in the summer.
- In the low desert of Arizona:
Start seeds indoors:
August – January
Plant seeds or transplants outside:
October – March
- For milder zones 7-10, alyssum may grow year-round, with blooms slowing down in the summer and picking up again when temperatures cool off.
In square foot gardening, allow 1 square foot per plant.
Flowers to Plant Outside & Seeds to Start Indoors Each Month in the Low Desert of Arizona.
• PLANTING GUIDE: Each month lists annual flowers and bulbs to plant outside & seeds to start indoors.
• BLOOMING GUIDE: Photos show what may be in bloom that month.
4. Use sweet alyssum to attract beneficial insects and as a companion plant
Plant alyssum as a companion plant near any aphid-prone plant in your garden (roses, lettuce, brassicas, etc.). Alyssum flowers are the nectar of choice for syrphid flies (hover flies). Syrphid-fly larvae love to eat aphids.
5. Learn how to grow alyssum and care for it as it grows
- Alyssum does best with regular water, but does not like soggy soil.
- Container-grown alyssum (especially hanging baskets) will need more frequent watering.
- Deadheading isn’t necessary, but occasional light-pruning encourages fuller plants and more blooms.
- Overwintered alyssum may get “leggy”; replant each year if desired.
- Feed plants that have been in the ground more than one season to encourage more blooms.
- Many varieties of alyssum drop seed and come back the following season.
Additional tips for alyssum:
- Alyssum is generally disease-free but can develop root and stem rot in heavy clay soils. Discard infected plants. To prevent this, decrease watering and plant in well-drained soil or raised beds.
- Four weeks after blooming, cut plants back by half to encourage a second flush of blooms.
- To naturalize sweet alyssum in a new location, spread spent flower heads over bare soil.
Arizona annual flowers planting guide helps you learn when to plant flowers in Arizona, and whether to plant seeds or transplants.