Sweet Alyssum -- A Tiny Plant with Big Impact
By Marie Harrison (can2grow) January 16, 2013
Sweet alyssum is a long-blooming annual or short-lived perennial. Growing only about 4 to 6 inches tall, it hugs the ground forming a dense groundcover. Narrow leaves about one inch long hardly show through clusters of tiny flowers that cover the plants over a long season. Flowers come in an amazing array of colors, including not only white, but also bronze, purple, rose, pink, wine red, lemon yellow, salmon, reddish copper, and all tints and shades in between. The website from Swallowtail Gardens shows many selections and gives an idea of the color variations that are available.
In my Zone 8B garden sweet alyssum is best suited to the fall, winter, and early spring garden. However, sometimes it remains in the garden year round. It almost seems perennial because seeds are produced that fall to the ground or are carried by the wind to nearby places. Because of the reseeding, it seems as if the same plants continue to bloom when in fact new seedlings are filling in. My favorite places to grow it are at the edges of sunny beds and around the edges of my herb garden. It is equally suited for hanging baskets and other types of containers.
Experience has taught me that seeds require light for germination. One spring I bought a packet of seeds and planted them, covering them lightly as I usually do. No plants came up. It was not until I bought a new packet and read the directions that I discovered what I had done wrong. Printed plainly on the packet was a statement that light is required for germination. Taking that advice to heart, I tried again. I prepared my bed as usual, sprinkled the tiny seeds on the surface of the soil, and patted lightly to be sure they had good contact with the soil. Lo and behold, I think every one of them came up. The tiny white flowers bloomed all spring and well into the summer. The following fall more plants came up where the old flowers had reseeded.
Seeds germinate in 8 to 15 days at temperatures between 65°F and 75°F. Light frosts seem to have no effect, but plants cannot endure a hard freeze. Most gardeners in Zones 7-11 enjoy sweet alyssum throughout the winter. In summer it may die out completely or look straggly if it manages to survive summer’s heat. While gardeners in southern part of the country enjoy it best as a cool season plant, gardeners in the upper third of the United States may find that it blooms throughout the summer.
Plant sweet alyssum in full sun to partial shade in organic, well-drained but moist soil for best performance. The colored types seem to appreciate a bit more shade than the white selections. If growth becomes lanky and flowering diminishes, shear back by about one third to initiate new growth and blooms. Garden plants should not need additional fertilizer during the growing season, but container-grown alyssum will require more frequent water and respond well to monthly feedings of a water soluble fertilizer.
Amiable Spouse and I frequently comment about the insects that buzz around the sweet alyssum. Some bees are always flying around, and I have seen butterflies and hundreds of tiny wasps gathering pollen or sipping nectar from the blossoms.
A walk into the garden on a cool, sunny day will reveal the sweet, honey-like scent that emanates from a bed of sweet alyssum. Most people seem to enjoy this scent, but others find it too overpowering or even offensive. One Dave’s Garden reader reported that it was the worst smell in the world and caused intense headaches. However, the overwhelming majority of comments on the DG website were positive.
Some gardeners reported that sweet alyssum was invasive in their gardens and that volunteer plants reverted to the somewhat gangly species. If this is a problem, select one of the recently introduced sterile types, such as ‘Snow Princess’®, a sterile hybrid from Proven Winners that is heat tolerant. Because energy is not used producing seeds, these plants are vigorous and bloom over a long season.
Sweet alyssum is readily available in flats at most garden centers in the spring and fall. Pick up a tray or so of these tiny giants to add a bit of sparkle to your landscape. Or pick up a packet of seeds and plant them where you want them to grow.
Thanks to Mgarr for the image of lobularia at Longwood Gardens.
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