Alyssum Flower Size

Strength in Numbers

• The sweet alyssum plant is 6 to 12 inches tall and produces a spreading mat of foliage that eventually covers an area of 1 foot or more. It produces massive numbers of tiny flowers in white or pastel colors, depending on the cultivar, usually from spring into mid-summer. Each four-petaled flower is tiny, about 1/2 inch or less in width, but flowers arise in a dense cluster at the end of each stem, giving the impression of a much larger blossom when viewed from a distance. The blossoms give off a sweet fragrance that attracts butterflies, bees and other pollinating insects.

Supporting the Blossoms

• You can maximize the size and number of alyssum blossoms by giving the plant ideal growing conditions. The best flowering occurs when the plant's grown in full sun, although it can tolerate some light shade, especially in the afternoon hours in regions with hot summer sun. Although the heaviest flowering is in spring through mid-summer, deadheading the plant by removing spent flowers regularly can induce a second, lighter flush of blossoms in late summer. If the plant begins to look leggy and its growth declines in summer's heat, cutting the plant back by about a half often spurs lush new growth that supports more flowering in the fall.

Planting as an Annual

• Sweet alyssum grows as a perennial in U.S. Department of Agriculture plant hardiness zones 5 through 9, but tends to decline in vigor after a few years, producing fewer and fewer flowers. Because of this, it's generally grown as an annual in the U.S. You can start with seedlings purchased at a garden center, transplanting them into a sunny spot that's well-drained but tending to stay moist. Alyssum also grows well when direct-seeded into the garden, but avoid covering the seeds, because they need light to germinate. You can also start seeds indoors four to six weeks before your last frost, hardening them off in a partially shaded spot outdoors for a week or two before transplanting to their final site.

Choosing a Color

• The alyssum plant typically has white flowers, with a cultivar called "Snowdrift" that has especially showy, brilliant white flowers on short, 3- to 6-inch-tall plants. Several varieties have colorful flowers, including "Rosie O'Day," an early-bloomer with rosy-red flowers that hold their color well, and "Trailing Rosy Red," a plant with rosy pink flowers on trailing stems that works especially well in a hanging basket. Alyssum is also available as a series of cultivars grouped according to their flower colors. These include the "Easter Bonnet" series, with white, purple or pink flowers, and the "Basket" series, with plants that bloom in white, pink, purple, yellow or peach.