The species only reaches around a foot tall with a slightly wider spread, but it quickly grows and reseeds itself to form a dense mat. This makes it an effective ground cover plant. You can direct sow seeds in the late summer or early fall, or you can start seedlings indoors over the winter to be planted after the last frost in the spring. These plants are fairly hardy and low-maintenance. They can tolerate drought and poor soil conditions. They’re also resistant to most diseases and pests, including deer. Plus, they attract beneficial insects, such as bees and butterflies, to your garden. But you will likely have to do some pruning to keep them looking neat. After the blooms fade, cut back yellow alyssum by 1/3 to 1/2 to promote reblooming. Likewise, cut it back by 1/3 to 1/2 if it begins to get too leggy. This also helps to prevent aggressive spread via self-seeding. You can divide the plants in the fall if you wish to propagate them.
Light
Yellow alyssum does its best flowering when grown in full sun. However, in hot climates the plant likely will enjoy some afternoon shade to prevent the foliage from depreciating.
Soil
Yellow alyssum likes average to sandy soil with excellent drainage. It can tolerate shallow and rocky soil. But heavy clay soil or other soil types that remain moist and drain poorly can cause root rot and kill the plant.
Water
This plant doesn’t require much water and thrives in dry soil. In fact, overwatering is one of the few factors that can be deadly to yellow alyssum. Because it has good drought tolerance, you’ll likely only have to water if you have an extended period without rainfall and your plant begins to wilt and lose its leaves. New plants in their first growing season need slightly more water than established plants, but still be aware that you don’t allow the soil to get soggy. Moreover, if you are growing your yellow alyssum in a container, be especially careful not to overwater. Wait for the soil to dry out between waterings, and verify that the container has good drainage.
Temperature and Humidity
Yellow alyssum has some cold tolerance and grows well from USDA hardiness zones 3 to 7. However, it struggles in hot and humid weather. Consequently, in the South many gardeners treat it as an annual, enjoying its spring flowers before the foliage depreciates in the summer heat and humidity.
Fertilizer
Fertilizer typically isn’t necessary for yellow alyssum unless you have very lean soil. Too much fertilizer can result in poor flowering and a scraggly growth habit. If you wish, you can fertilize every other year in the fall with a low-dose organic fertilizer or compost.
Varieties of Yellow Alyssum
There are several beautiful varieties of yellow alyssum that vary slightly in appearance, including:
Aurinia saxatilis ‘Citrinum’: This is a compact yellow alyssum cultivar, growing around 12 inches to 15 inches tall. It features bright lemon-yellow flowers.Aurinia saxatilis ‘Compactum’: This cultivar is a dwarf variety. It has a compact and dense growth habit, reaching around 8 inches to 10 inches tall. Its blooms are a bold yellow color.Aurinia saxatilis ‘Dudley Nevill Variegated’: This cultivar grows to around 10 inches tall and spreads to around 18 inches wide. It features small apricot-yellow flowers and has hairy, soft, gray-green foliage with creamy white margins.Aurinia saxatilis ‘Gold Dust’: This yellow alyssum cultivar has a mounding growth habit. It only reaches around 6 inches to 12 inches tall and spreads to between 1 foot and 2 feet wide. It also sports hairy, soft, gray-green foliage. And in the spring it is heavily covered in bright yellow blooms.
