How to Grow Sweet Alyssum From Seed

Sweet alyssum is a fast, forgiving annual. Direct-sow it outdoors around your last spring frost, once the soil can be worked, or start seeds indoors 4 to 6 weeks earlier for a quicker start. Because it grows and flowers so quickly, many gardeners sow it several times through spring and summer for continuous bloom. It loves cool weather and often slows in midsummer heat, then bounces back in fall, and in frost-free areas it can flower nearly year round.

Sweet alyssum seeds are tiny and need light to germinate, so surface-sow them: scatter the seeds over moist soil and press them in gently for good contact, but do not cover them. Keep the surface consistently moist, misting rather than blasting so you do not wash the fine seeds away, and sprouts appear in about 5 to 14 days. Grow in full sun to light shade in well-drained soil, in the ground, along a bed edge, or spilling from a pot or basket. Thin or space plants about 6 to 8 inches apart; they will quickly knit together into a flowering carpet.

Sweet alyssum is about as low-maintenance as flowers get. Keep the soil evenly moist, especially in pots and hanging baskets, and give a light feed now and then for steady bloom. If the plants get straggly or stop flowering in midsummer heat, shear them back by about a third and they will flush out with fresh growth and a new wave of flowers, a trick worth repeating. It is naturally deer resistant and rarely bothered by pests. Modern varieties are largely self-cleaning, so you get a long show with little fuss, and in mild coastal and Southern gardens it can bloom through winter, while in hot inland climates it performs best in spring and fall.

Sweet alyssum is a star companion plant. Its tiny flowers are a favorite of hoverflies and other tiny beneficial insects whose larvae devour aphids, so tucking it among vegetables is a genuine pest-control move. These four make especially good companions, and you can add any of them in one click:

Sweet alyssum is grown for its honey-scented carpet of bloom rather than for cutting, so the main task is the occasional shear to keep it fresh. To collect your own seed, let some flowers fade and form their tiny seed pods, then snip the dried stems and rub out the fine seeds over a bowl. Store them cool and dark. In many gardens, though, alyssum simply reseeds itself, and volunteer seedlings appear right where you want a soft flowering edge.

Sweet alyssum is the ultimate flowering filler and edging plant. Its low, spreading mounds of tiny, honey-scented flowers soften the front of a border, spill out of pots and hanging baskets, and knit together into a living mulch between vegetables and taller flowers. Best of all it is a pollinator powerhouse: the blooms draw in bees and especially hoverflies, whose larvae eat aphids, making alyssum one of the most useful companion plants in a kitchen garden.

• Stops blooming in summer: heat makes alyssum stall. Shear the plants back by a third, keep them watered, and they will reflush as it cools.
• Leggy, sparse growth: give it enough sun and shear it to keep the mounds compact and full.
• Damping off in seedlings: sow thinly on the surface, avoid overwatering, and give good airflow.
• Washed-away seeds: the seeds are dust-fine, so mist gently rather than pouring water on freshly sown beds.