Sweet alyssum is a colorful carpet of tiny flowers that can be used to blanket your garden or landscape. Native to Europe, the low-growing foliage grows quickly, covering the ground with tiny cross-shaped, four-petal flowers within two months of being planted. Its gray-green leaves are slightly hairy, narrow, and lance-shaped.
Easy to grow from plant or seed, sweet alyssum is a cool-season flower that can be set out in early spring once all danger of frost has passed (in frost-free climates, sweet alyssum can also be grown throughout the fall and winter). Most varieties will fade in the heat but bloom again in the fall.
|Botanical Name||Lobularia maritima|
|Common Names||Sweet alyssum, alyssum, carpet flower|
|Plant Type||Herbaceous perennial|
|Mature Size||3–9 in. tall, 6–12 in. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Spring, Fall|
|Flower Color||White, pink, purple|
|Hardiness Zones||5–9 (USDA)|
Sweet Alyssum Care
Sweet alyssum is nearly unmatched when it comes to ease of care, and is hardy to both heat and drought. The flowers have a lively, honey-like fragrance and are actually members of the mustard family—they will self-sow and can provide bright color year-after-year, especially in milder climates. Sweet alyssum is generally problem-free, although aphids can become a pest, especially when the plants are under stress.
As sweet alyssum plants spread, they create a living mulch under taller plants. You can use sweet alyssum along edges, in the garden, or to fill nooks and crannies on walkways and walls. The tight, free-flowering plants are also great in hanging baskets and containers.
Sweet alyssum loves full sun, but it does not like prolonged dry periods. If your region is especially hot and dry, a slightly shaded area will work best for this plant, though you should keep in mind that it can get stem rot or leaf blight if too much shade prevents the leaves and soil from completely drying out. Generally, you should aim to plant your sweet alyssum somewhere where it can get six to eight hours of sunlight a day.
Sweet alyssum plants prefer soils that are of medium moisture and well-draining. They're tolerant of many different planting locations and can even be found on sandy beaches and dunes—though they can also grow on cultivated fields, walls, slopes, and even in cracks in sidewalks or walls. The plants will do poorly in boggy soil or where drainage is a particular problem.
Provide your sweet alyssum plants with at least an inch of water every week, watering them more frequently during hot or dry spells. Make sure the water drains well, otherwise the plant is susceptible to rot. If you plant your sweet alyssum atop stone (or anywhere that dries out quickly), you will need to provide extra water—the same holds true of hot or dry weather.
Temperature and Humidity
In temperate weather, gardeners may be able to grow sweet alyssum all year long, though the actual plants themselves are short-lived. Typically, they self-seed so much that while it seems as though the same plants are surviving all year long, the reality is that new seedlings are filling in. Sweet alyssum plants repeat bloom, although many varieties tend to stop flowering in heat, only to often pick back up again in the fall. In areas of high humidity, you should compensate by reducing the amount of water given to plants.
Typically, in-ground sweet alyssum plants do not need any fertilizer unless your soil is poor. Plants grown in containers will need monthly feedings using a water-soluble fertilizer for the container plants.
Sweet Alyssum Varieties
There are several common varieties of sweet alyssum:
- 'Easter Bonnet': An early blooming variety, typically found in lavender or white
- 'New Carpet of Snow': A low-growing variety, covered in petite white flowers
- 'Pastel Carpet': A varietal whose blooms blend pink, lavender, and cream
- 'Snow Crystals': A tidy, mounding variety with translucent white flowers
How to Grow Sweet Alyssum From Seed
You can start sweet alyssum from seed or plant, both of which are widely available at nurseries (though some new cultivars are not available as seeds). To start from seed, simply scatter the seeds atop the soil and press them down lightly so they make good contact with the dirt but are still exposed to light. Keep the soil moist until germination, then water whenever the soil feels dry.
You can direct seed outdoors once the soil feels warm to the touch or start alyssum seed indoors about eight weeks before your last frost date (do not transplant until after all danger of frost). Alyssum is somewhat frost-tolerant once established, but tender transplants are not hardy enough for frost.
Deadheading sweet alyssum will keep the plants flowering—they will set new buds quickly. If you have a large drift of plants, shearing them by one-third would be an easier option than deadheading. Some varieties will readily re-seed themselves, but the plants tend to revert to the somewhat gangly species, so pruning will aid in that.