When to start alyssum seeds indoors?

Let us show you how to grow Alyssum from seed using these tried and true techniques. Alyssum is an easy-to-grow annual that is both decorative and useful. It plays a key role in Companion Planting and can be used as a cover crop to attract insects, smother weeds, and increase fruit set in vegetable beds.

Annual plants also known as Sweet Alyssum.

Lobularia maritima
Family: Brassicaceae


Season & Zone
Exposure: Full sun or partial shade.
Zone: 3-10, not winter hardy

Start indoors 6-8 weeks before the last frost, around the beginning of March to early April here on the coast. Transplant out after all danger of frost has passed. Or, direct sow while some danger of light frost still exists. It’s very easy, either way.

Sow seeds on the surface of the soil. If starting indoors, use a sterilized seed starting mix and maintain a soil temperature of 12-21°F (55-70°F) under bright lights. Seeds require light to germinate, so do not cover them. They should sprout in 5-14 days.

Transplant 20-30cm (8-12″) apart once all risk of frost has passed. Watch for slug damage in the early spring. Alyssum prefers a moist loamy soil with a pH in the 6.0-7.0 range, but it’s adaptable. It is tolerant of dry soil, and can be used for xeriscaping. If growth slows in mid-summer due to heat, shear plants back by half to encourage compact growth and a second bloom. May self sow.

Companion Planting
Alyssum is very attractive to pollinators, and useful as a mulch to keep weeds down between rows.

More on Companion Planting.

How to Grow and Care for Your Sweet Alyssum

Growing sweet alyssum remains an easy task. The fluffy plant with its myriad flowers continues to be one of the top choices for filling in spots in the garden, to form a lovely scented border for a flower bed, and as a frilly filler for your outdoor pots of flowers.

This versatile, spreading tiny plant is sturdy enough to grow nearly everywhere with the proper care. It has even become a naturalized flower in some areas. Sweet alyssum loves both heat and is tolerant to drought. And if you live in warmer climates, sweet alyssum may even self-seed, bringing the dainty cluster of flowers back year after year.

Closeup photograph of a bee enjoying the white lobularia maritima (alyssum flowers)

Sweet Alyssum Plant Information

Sweet alyssum plants are annual flowering plants that are a great addition to the flower bed, flower pots, or alpine rock gardens. They perform well on slopes and can help prevent erosion. Some other quick facts about sweet alyssum include:

  • Height is from 6 -12 inches.
  • Colors range in blue, pink and white.
  • The plant is a free flowering annual.
  • Alyssum is low maintenance.
  • It is fragrant.
  • It is excellent for flowerbeds and containers.

Sweet Alyssum Guide Questions and Answers

Is sweet alyssum an annual or perennial?

Lobularia maritima or alyssum maritimum is the botanical name for sweet alyssum. It is helpful to know the botanical names if you want an exact type of alyssum or to differentiate alyssum from other similar border plants. Alyssum comes back each year through self-seeding in warmer climates. If you garden in warn climates, your alyssum will appear to be a perennial, but it is not. Alyssum self-seeds and frequently reoccurs in the same place every year in warmer areas.

Alyssum grows as an annual in cooler climates. If you live in cold climates, you will need to start plants indoors in the spring or sow the seeds outdoors in the borders of your flowerbed. Either way, sweet alyssum comes in a variety of complementary colors that suit any flowerbed’s plantings.

When should sweet alyssum seeds be planted?

Planting time for alyssum seeds is determined by the USDA Planting Zone in which you live. Warmer climates may plant alyssum seeds in the late winter, while gardeners planting alyssum outdoors should wait until the soil is warm and there is no more danger of freezing before they plant. Some experts suggest that the soil temperature should be 60 f or 16 c before planting alyssum seeds or plants outdoors. Many seed packages have information about when to directly plant seeds into the soil in your area.

Seedling holding close up of pretty pink, white and purple alyssum flowers, of the cruciferae annual flowering plant

If you live in the north or want to get a head start on your planting, alyssum is quickly started indoors using pots and potting soil. Many greenhouses also carry the charming plants during the proper planting time for your region. Planting the seeds is much less expensive than buying the plants, however.

Alyssum remains an easy plant to grow from seed, too. To grow alyssum indoors, place some potting soil in individual containers. Water the soil thoroughly. Then sprinkle the tiny seeds on top of the ground. Press the seeds into the dirt, but don’t cover the seeds. Keep the potting soil evenly moist. It takes from 15 to 20 days until you will see the first sprouts of alyssum plants. Keep watering the soil when necessary and be patient, and soon your plants will start.

How do I grow alyssum plants?

Alyssums are notoriously easy to grow. First, select the type of alyssum you think would make the best border for your flower bed. Or choose a color of alyssum that would look lovely trailing in your alpine or rock garden. If you prefer hanging baskets, choose a color of alyssum that accents the colors of your flowers or plants in your flower pots.

Where do I plant my alyssum flowers?

Next, place your alyssum seeds directly on top of the soil. Alyssum loves full sun, so find your seeds a sunny spot in your garden, or transplant you the plants you started indoors outside to an area of full sun. Another good choice for location is a place in your garden that has partial sun during the heat of the day. Alyssum doesn’t like extreme heat conditions and doesn’t mind a break from the sun during part of the day.

A flowerbed with the sun in the morning and a bit of shade in the afternoon is perfect for alyssums, especially if you live in a warm climate. A porch with shade for part of the day also is ideal for the darling little flower.

What type of soil does an alyssum plant need?

Alyssum does well in many types of soil, making it an ideal border or filler plant for any flowerbed. Test the ground drainage by digging a small hole in the place where you want to place your plant. Then fill the hole with water. Watch the speed in which the water drains. If it drains slowly, add some sand or compost to the soil to help it drain properly. Remove any weeds or debris that might be in the area you are placing the plant.

Then place the plant gently into the hole, put soil around the plant and water it in thoroughly. Or smooth out the ground, sprinkle it with alyssum seeds and gently pat the seeds into the top of the soil without covering the seeds. Do not overwater your alyssum plants.

Alyssum Flower Care

Alyssum takes little care beyond watering and weeding around the plants. Alyssum flowers, as well as any flowering plant, enjoy adequate water and fertilizing. Just use whatever fertilizer you use for the rest of your flower pots or flower bed, and your alyssum will be adequately fed.

Once the plants have gone through a blooming period, you will need to trim them back to encourage further blooming. If you don’t deadhead, the plant will set seed and quit blooming. You don’t need to carefully dead head each flower, however. Simply take a sharp set of gardening scissors and trim your alyssum back by about one third to encourage new growth.

The frothy sweet alyssum plant is easy to start, easy to grow, comes in a variety of colors and is disease resistant. Alyssum may be the plant you’ve been looking for to polish the look of your garden or the pots on your porch. Try adding some sweet alyssum to your garden today to soften the edges of your plantings.

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Sweet Alyssum Flowers – Tips For Growing Sweet Alyssum

Few annual plants can match the heat and drought hardiness of sweet alyssum. The flowering plant has naturalized in the United States and thrives in a wide range of regions. Sweet alyssum flowers are so named for their lively fragrance and are members of the mustard family. While not frost tolerant, sweet alyssum plants will self sow and can provide you with year after year of bright color in milder climates.

Sweet Alyssum Plants

Sweet alyssum flowers (Lobularia maritima syn. Alyssum maritimum) are useful in alpine rock gardens, borders, planters, hanging baskets and dry zones. They are small plants that may get 3 to 6 inches tall and produce clusters of tiny flowers in clumps. The blooms come in pink, salmon, purple, white and yellow. Flowers arise in June to October and can be encouraged to rebloom by cutting back spent flowers.

How to Grow Alyssum

Growing sweet alyssum requires well-drained soil with moderate moisture. The plants are tolerant of many types of soils and make a cheerful accent in many situations.

Start from seed in early spring in seed flats indoors and transplant after the danger of frost has passed. Surface sow the tiny seed and keep lightly moist until germination, which is usually 15 to 20 days. When the seedlings have several pairs of true leaves and soil temperatures are at least 60 F. (16 C.) degrees, transplant them into a prepared garden bed.

Learning how to grow alyssum is easy and a packet of seeds is cheaper than purchasing bedding plants.

How to Plant Alyssum

Learning how to plant alyssum is easy. You can also plant sweet alyssum flowers from seed straight into the garden in mild climates. Choose a location that has full sun, although sweet alyssum plants can tolerate partial shade as well.

Prepare the soil prior to planting by weeding, working in organic amendments and raking out any obstructions. Before transplanting your seedlings, check the drainage in your soil by digging a hole and filling it with water. If soil doesn’t drain quickly, work in compost, leaf litter or grit, such as sand, to increase the porosity of the soil.

Keep the bed weed free to reduce competition for resources and provide even moisture.

Sweet Alyssum Flower Problems

Sweet alyssum plants require little maintenance. While alyssum is relatively maintenance free, it will do poorly on boggy sites and where inadequate moisture is provided.

It is prone to few pest problems but may get stem rot or leaf blight where too much shade prevents the leaves and soil from drying out. Botrytis blight is a particular problem of sweet alyssum plants when they are grown in overly wet areas.

Trim back the stems after blooming for an endless display of colorful sweet alyssum flowers.

Annuals for Part to Full Shade

As a guide, partial shade refers to those areas that are shaded for 4-6 hours per day. Morning sun or east facing locations are typical or dappled light obstructed by trees. Afternoon sun is also considered within the partial shade parameters but because of the intensity of afternoon sun, these areas can become quite hot and may require attention to timely irrigation. Full shade areas receive no direct sun only indirect light. North sides of structures or under fully leafed out trees are examples.

Calico Plant – Alternanthera ficoidea

Height: 6-18 inches.

Width: 6-24 inches.

Bloom: insignificant.

Cultivars: ‘Little Ruby’, ‘Purple Knight’, ‘Party Time’, ‘Red Tread Leaf’.

Notes: Plant valued for colorful, attractive foliage. Flowers are insignificant. Best in partial shade.

Rex Begonia – Begonia rex-cultorum

Height: 12-18 inches.

Width: 12-15 inches.

Bloom: assorted colors throughout the season.

Cultivars: ‘Escargot’, ‘Persian Swirl’, ‘New York’, ‘Lalomie’, ‘Fireworks’.

Notes: Dramatic, large, colorful foliage. Best in shade.

Wax Begonia – Begonia x semperflorens

Height: 6-12 inches.

Width: 6-12 inches.

Bloom: Assorted colors all summer.

Cultivars: ‘Big’ series, ‘Whopper’ series, ‘Bada Bing’ series, ‘Cocktail’ series.

Notes: Outstanding continuous color. Adaptable from sun to shade. Green and red foliage types.

Tuberose Begonia – Begonia tuberhybrida

Height: 6-12 inches.

Width: 6-12 inches.

Bloom: Large, assorted colors.

Cultivars: ‘Non-Stop’ series, ‘Illumination’ series, ‘Million Kisses’ series, ‘Sparks Will Fly’.

Notes: Noteworthy foliage with dramatic flowers. Comes in both upright and cascading types. Best in shade.

Angel Wing Begonia – Begonia coccinea

Height: 12-18 inches.

Width: 12-18 inches.

Bloom: Reds and pinks in clusters.

Cultivars: ‘Dragon Wing’ series, ‘Baby Wing’ series.

Notes: Vigorous plant. Large shiny foliage. Dramatic clusters of flowers. Best in part shade to shade.

Caladium – Caladium bicolor

Height: 12-15 inches.

Width: 12-15 inches.

Bloom: Insignificant.

Cultivars: Fancy Leaf Type: ‘Aaron’, ‘Carolyn Whorton’, ‘Candidum’, ‘Fannie Munson’,
Strap Leaf Types: ‘Jackie Suthers’, ‘Sweetheart’, ‘Red Frill’, ‘Rosalie’, ‘Pink Gem’.

Notes: Colorful foliage. While all caladiums are suggested for and do well in full shade areas the strap-leaf cultivars listed above do very well in full sun locations.

Fuchsia – Fuchsia x hybrid

Height: 18-24 inches.

Width: 12-18 inches.

Bloom: Reds, pinks, lavenders.

Cultivars: ‘Gartenmeister Bonstedt’, ‘Thalia’, ‘Koralle’.

Notes: The cultivars listed are triphylla types that tend to perform much better under Midwestern garden conditions. Best in part shade.

Polka Dot Plant – Hypoestes phyllostachya

Height: 6-12 inches.

Width: 6-12 inches.

Bloom: Insignificant.

Cultivars: ‘Splash’ series, ‘Confetti’ series.

Notes: Colorful spotted foliage in pinks and whites. Best in part shade.

Bloodleaf – Iresine herbstii

Height: 10-15 inches.

Width: 10-15 inches.

Bloom: Insignificant.

Cultivars: ‘Blazin Lime’, ‘Blazin Rose’, ‘Purple Lady’ (trailing).

Notes: Multicolored shiny foliage in shades of cream and red or lime and cream. Best in part shade to shade.

Lobelia – Lobelia erinus

Height: 6-12 inches.

Width: 6-12 inches.

Bloom: White, blue, lavender.

Cultivars: ‘Techno Heat’ Dark Blue, ‘Hot Springs’ series, ‘Riviera’ series, ‘Cascade’ series.

Notes: Fine textured foliage and flowers. Best in part shade.

Sweet Alyssum – Lobularia maritima

Height: 6-8 inches.

Width: 8-12 inches.

Bloom: White, pink, purple.

Cultivars: ‘Giga White’, ‘Easter Bonnet’, ‘Snow Crystals’, ‘Snow Princess’.

Notes: Continuous bloom with newer cultivars holding up well to summer heat. Tolerant of cool temperatures. Best in full sun to part shade.

Salvia – Salvia splendens

Height: 18-24 inches.

Width: 12-18 inches.

Bloom: Red, white, purple.

Cultivars: ‘Red Hot Sally’, ‘vista’ series, ‘Salsa’ series’ ‘Lighthouse’ series.

Notes: Spike-like flowers, clean looking foliage. Best in sun to part shade.

Wishbone Flower – Torenia fournieri

Height: 6-12 inches.

Width: 12-18 inches.

Bloom: Blue, pink, red, white.

Cultivars: ‘Summer Wave’ series, ‘The Clown; series, ‘Kauai’ series.

Notes: Snapdragon-like flowers on compact bushy plants. Best in part shade to shade.

New Guinea Impatiens – Impatiens hawkeri

Height: 12-24 inches.

Width: 2-3 feet.

Bloom: Assorted colors.

Cultivars: ‘Sunpatiens’ series, ‘Celebration’ series, ‘Celebrette’ series.

Notes: Very large flowers on vigorous plants. Good alternative to standard bedding impatiens (Impatiens walleriana). Best in part shade to shade.

Browallia – Browallia speciosa

Height: 10-14 inches.

Width: 6-12 inches.

Bloom: Soft blue.

Cultivars: ‘Endless Illumination’, ‘Bells’ series.

Notes: Older reliable annual for abundant flowering. Best in part shade.

Coleus – Plectranthus scutellarioides

Height: 12- 36 inches.

Width: 18-24 inches.

Bloom: Insignificant.

Cultivars: ‘Kong’ series, ‘Wizard’ series, ‘Versa’ series.

Notes: Excellent foliage plant for shade offering numerous color and textural combinations. Cultivars listed are best for shade but there are numerous cultivars that are outstanding for full sun sites.

  • Annuals for Part to Full Shade
  • Annuals for Sunny, Dry Sites
  • Perennials for Dry Shade
  • Perennials for Shade
  • Perennials for Sunny, Dry Sites
  • Perennials Tolerant of Moist to Wet Soil
  • Shade Tolerant Ornamental Grasses and Grass-Like Plants

Sweet Alyssum

Sweet Alyssum

Sweet alyssum is a wonderful cool-season annual that seems to bloom its head off in mild spring weather. This plant has been a long-time favorite because of its dainty blossoms on tight mounds of foliage. These plants work great as landscape edging plants in the garden and even in containers. Plant them in masses to create an abundance of its light honey fragrance. Sweet alyssums are great for attracting pollinators to your garden.

genus name
  • Lobularia maritima
  • Part Sun,
  • Sun
plant type
  • Annual
  • Under 6 inches,
  • 6 to 12 inches
  • Up to 12 inches
flower color
  • Purple,
  • White,
  • Pink
foliage color
  • Blue/Green
season features
  • Spring Bloom,
  • Fall Bloom,
  • Summer Bloom
problem solvers
  • Groundcover
special features
  • Low Maintenance,
  • Fragrance,
  • Good for Containers
  • 9,
  • 10,
  • 11
  • Seed,
  • Stem Cuttings

Colorful Combinations

Alyssum is most often found in a crisp, clean white. However, sometimes you will see the flowers in deep purple, light pink, or even a soft peach color. The abundant white blooms make this plant easy to use in garden designs—they can truly go with everything. Put them at the bases of plants to cover the ground and draw even more pollinators to your garden. Sweet alyssums are also valuable for their early spring blooms when nothing else has taken off.

Alyssum Care Must-Knows

Alyssums are easy plants to start from seed. Because they are cool-season annuals, they can be sown from seed directly in your garden several weeks before the last frost. They don’t mind the cold, as long as it isn’t a hard freeze. If you want an even quicker impact in your garden, start seeds indoors 5-6 weeks before the last frost date. It is best to plant alyssum in well-drained soil, keeping plants evenly moist throughout the season.

Be sure to give your alyssums plenty of sunshine. In northern climates with mild summers, full sun is ideal, which allows plants to keep blooming as much as they can. In areas where summers are on the warm side, plant alyssums in part sun, especially protected from the hot afternoon sun. This helps extend your bloom time a little longer. If the season does get too hot and plants stop blooming, shear plants back by about half. This will encourage new growth and give your plants a good base to bloom again once cool weather returns in fall.

Because alyssum is a cool-season annual, plants will generally stop blooming to conserve energy in the summer. However, there are some varieties that are much more tolerant of the heat and will give you more bloom time. In most cases, varieties with darker-colored blossoms tend to have less heat resistance than the pure white varieties.

New Innovations

Because sweet alyssum is such a popular garden plant, there has been a lot of research done in trying to make them even better for the garden, most of which has focused on creating varieties that are more heat tolerant and continue to bloom throughout the summer. Varieties like ‘Snow Princess’ have been great breakthroughs in this area, and have proven to persist through the summer. Soon, there may even be colored varieties that can venture into the fall!

Garden Plans For Sweet Alyssum

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More Varieties of Sweet Alyssum

‘Clear Crystal Lavender’ sweet alyssum

Lobularia maritima ‘Clear Crystal Lavender Shades’ is an extra-vigorous selection with fragrant, larger-than-typical lavender blooms. It grows 10 inches tall and 14 inches wide.

‘Easter Basket’ sweet alyssum

Lobularia maritima ‘Easter Basket Blend’ bears blooms with violet, rose, or pink flowers on 4-inch-tall plants.

‘Easter Bonnet’ sweet alyssum

Lobularia maritima ‘Easter Bonnet Pastel Mix’ offers soft pink, lavender, and white blooms on tidy 4-inch-tall plants.

‘Frosty Knight’ sweet alyssum

Lobularia ‘Frosty Knight’ is a novel variety that has cream-edged green leaves as an added bonus to the bountiful white blooms.

‘New Carpet of Snow’ sweet alyssum

Lobularia maritima ‘New Carpet of Snow’ bears white blooms on tidy 3-inch-tall plants.

‘Rosie O’Day’ sweet alyssum

Lobularia maritima ‘Rosie O’Day’ bears rosy-lavender flowers on compact 4-inch-tall plants.

‘Snow Crystals’ sweet alyssum

Lobularia maritima ‘Snow Crystals’ has fragrant, extra-large flowers on vigorous plants.

‘Snow Princess’ sweet alyssum

Lobularia maritima ‘Snow Princess’ is an exceptionally vigorous variety that’s heat tolerant and bears clusters of white flowers that are much larger than older varieties. It’s strongly fragrant, as well, and grows 6 inches tall but can trail to 5 feet.

Plant Sweet Alyssum With:

Nemesia is a charming cool-season annual with pretty little snapdragon-shape flowers—often fragrant—that bloom in a wide range of colors. It does best in spring and fall (winter in mild-winter climates), though some varieties have better heat-tolerance than others. In cool-summer areas, such as the Pacific Northwest, nemesia will continue to bloom right through the summer into fall. Nemesia prefers moist, well-drained soil that’s rich in organic matter.

From tiny, cheerful Johnny jump-ups to the stunning 3-inch blooms of Majestic Giant pansies, the genus Viola has a spectacular array of delightful plants for the spring garden. They’re must-haves to celebrate the first days of spring since they don’t mind cold weather and can even take a little snow and ice! They’re pretty planted in masses in the ground, but also cherished for the early color they bring to pots, window boxes, and other containers. By summer, pansies bloom less and their foliage starts to brown. It’s at this time that you’ll have to be tough and tear them out and replant with warm-season annuals, such as marigolds or petunias. But that’s part of their charm—they are an ephemeral celebration of spring!

Stock offers a wonderfully spicy, distinctive scent. Plant it in spring several weeks before your region’s last frost date; this annual thrives in cool temperatures and stops blooming once hot weather arrives. It’s especially wonderful in window boxes and planters at nose level, where its sometimes subtle effect can best be appreciated. Stock is slightly spirelike and comes in a wide range of colors. It makes a great cut flower, perfuming bouquets as well as the border. It grows best in full sun or part shade and moist, well-drained soil.

Varieties come in different shades of purple and pink, varying heights and spreads, some with double flowers (on varieties that florists use) and some with larger flowers.

‘Snowdrift’: white flowers are larger than traditional alyssum. Grows from 3 to 6” tall.

‘Easter Bonnet’ Series: blooms earlier in the season and retains its mounded shape and attractive appearance longer into the growing season than traditional alyssum. White, purple and pink shades for flowers.

‘Basket’ Series: these plants spread quickly, and are grown especially for hanging baskets. Flowers in shades of white, pink, purple, yellow and peach.

‘Aphrodite’ Series: white, yellow, peach, purple and pink shades for flower colors. One of the few annual alyssum varieties with yellow blooms.

‘Wonderland’ Series: purple, white or pink flowers on compact (3 to 6” tall) plants.

‘Snow Crystals’: flowers are white and larger than traditional alyssum flowers.

‘Rosie O’Day’: early blooming, 4” tall plant with spread of nearly 1’. Rosy red flowers hold their color long into the growing season.

‘Trailing Rosy Red’: rosy pink flowers on long, trailing plants. Excellent for hanging baskets.

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