Plant taxonomy classifies yellow alyssum flowers as Aurinia saxatilis (sometimes given as Aurinia saxatile). Occasionally, you will still see the older classification, Alyssum saxatile. The cultivar 'Compacta' bears the common names, "Basket-of-Gold" and "Dwarf Goldentuft." The name 'Compacta' signifies that the cultivar stays smaller than the species plant. This genus belongs to the mustard family of plants known as Brassicaceae.
Unlike the annual alyssum plants (Lobularia maritima) widely sold at garden centers (sometimes called "sweet alyssum") and commonly used as white bedding plants, yellow alyssum flowers are herbaceous perennials.
Yellow Alyssum Characteristics
These perennial alyssum plants have a spreading habit and will put out clusters of small yellow flowers on upright stalks in April or May (depending on where you live). The leaves are also an attractive blue-gray color. The species plant reaches at most 1 foot in height with a spread of 18 inches. It's shorter variation, the 'Compacta' cultivar, will often reach only eight inches tall with a spread of 12 inches. It reseeds itself readily and spreads to form a dense mat, making it an effective ground cover. The plant is reported to have naturalized in parts of New England (of the United States).
The outstanding feature of this perennial undoubtedly is its impressive floral display which blooms in masses in the spring. Do not, however, expect a nice fragrance from this plant; in fact, the flowers are quite bad-smelling.
Sun and Soil Requirements
Yellow alyssum flowers are commonly grown in United States Department of Agriculture (USDA) plant hardiness zones 3 to 7. They can be grown in zones 8 to 10 but will be short-lived there.
Uses and Care
Yellow alyssum flowers are popular as ground covers for border plantings and for rock gardens. In rock gardens, their foliage will cascade nicely over the rocks. They're also a traditional choice for cottage gardens.
After the blooms fade, cut back these perennial alyssum plants by one third to promote reblooming. Likewise, cut them back by one third if they begin to get too leggy. Divide the plants in fall if you wish to propagate them. Fortunately, these hardy plants are deer-resistant perennials, so you do not have to worry about protecting them from Bambi.
Similar Perennial Plants
Alyssum idaeum is a very similar perennial alyssum plant and also used in rock gardens. However, Aurinia saxatilis is much more popular.
Both Alyssum idaeum and Aurinia saxatilis are sometimes referred to as "madworts." The suffix, "-wort," simply means"plant" in Middle English. Additionally, the inclusion of "mad" in the name is no mistake—these plants were used in folk medicine where they were regarded as antidotes to rabies.
The origin of the botanical name Aurinia saxatilis is much more straightforward. Aurinia derives from the Latin word, aureus, which means "golden" and refers to the color of this perennial's flowers. Meanwhile, saxatilis is also from Latin and indicates that this plant "lives among the rocks," a reference to its native habitat in Europe where it's found growing on rocky hillsides.