Horticultural Planning Records Est. data · NOAA 1991–2020 · USDA 2023

Flower · Brassicaceae

How to Grow Sweet Alyssum

Cool season Half-hardy Full sun
Days to maturity 45–60
Spacing 6"
Plants / sq ft 3
Season Cool

Planting Sweet Alyssum

Sweet Alyssum is a cool season flower in the Brassicaceae family. Getting the timing right is the difference between a strong stand and a disappointing one, so the windows below are given relative to your own last spring frost and first fall frost rather than a generic calendar date. Look up your local frost dates and count back or forward from there.

Sweet Alyssum is started indoors 4–6 weeks before your last spring frost date, giving seedlings a head start before they move outside.

You can sow Sweet Alyssum directly into the garden 0–2 weeks before your last frost.

Sweet Alyssum can be grown by direct sowing and starting indoors. Starting indoors gives the longest, most controlled season, while direct sowing is simplest where the season is long enough.

Spacing and Planting Depth

Give Sweet Alyssum room to mature. The figures below come from verified extension and seed-supplier data for typical varieties.

Spacing in row6 inches
Row spacing8 inches
Plants per sq ft3
Planting depth0 inches
Sun requirementFull sun

Days to Maturity

Sweet Alyssum reaches maturity in 45–60 days from transplant.

Sweet Alyssum is ready to harvest after about 53 days. Harvest before summer heat or, for fall crops, before a hard freeze, to keep quality high.

Conditions and Care

As a cool-season flower, Sweet Alyssum does its best growing in the cooler weather of spring and fall and tends to bolt or turn bitter in summer heat. It is half-hardy — it withstands light frost but should be protected from a hard freeze.

Sweet Alyssum needs full sun — give it at least six hours of direct light a day for the best growth and flavor. Sow seed about 0 inches deep — small seed is sown shallow and barely covered, then keep the soil evenly moist until seedlings establish.

Sweet Alyssum belongs to the Brassicaceae family; rotating where you grow members of this family each year helps limit the build-up of soil-borne pests and disease. Sweet Alyssum is generally grown as a single planting each season rather than succession sown.

Companion Plants

Pairing Sweet Alyssum with the right neighbors can improve growth and deter pests; a few combinations are best avoided.

Grows well with: Lettuce (Loose-leaf), Tomato

Growing Notes

Low groundcover; attracts hoverflies. Surface-sow.

Plan your Sweet Alyssum schedule

Sweet Alyssum is typically grown as a single planting per season rather than succession sown. Plan your full garden →

Data sources
  • Johnny's Selected Seeds