Sunrose (Helianthemum), often known as rock rose or frostweed, is a vibrant, low-growing perennial that brings a burst of color to various landscapes. This woody-stemmed plant is a popular choice for gardeners, offering durable beauty. Its spreading habit and cheerful blooms make it an excellent selection for rock gardens, borders, and ground cover applications.
Discovering Sunrose
Sunrose plants are low-lying shrubs, typically 8 to 12 inches tall and spreading up to 3 feet wide. Their evergreen foliage often displays a silvery-green hue, sometimes appearing lightly frosted. These plants produce five-petaled, rose-like flowers, about 1 inch in diameter, available in shades of pink, red, orange, yellow, and white. While individual flowers typically open for only one day, their profusion creates a spectacular display from late spring to early summer, lasting up to two months. Sunrose is drought-tolerant and thrives in sunny, dry, lean soil environments.
Planting Sunrose
Plant sunrose in an optimal site that receives full sun exposure, ideally at least six hours daily. While partial shade is tolerated in very hot southern climates, ample sunlight promotes abundant flowering.
Well-draining soil is essential; sunrose prefers sandy, rocky, or gravelly loams with a neutral to mildly alkaline pH (6.0-8.4). Avoid or amend heavy clay soils, as poor drainage can lead to root rot.
Space plants 2 to 3 feet apart for ground cover. Sunrose dislikes root disturbance, so plant them in their permanent garden positions as soon as possible after purchase. Provide consistent moisture until plants are well-established.
Ongoing Sunrose Care
Once established, sunrose requires minimal watering; water only when the soil has completely dried out to prevent root rot. Maintaining full sun exposure is important for continuous, vibrant blooming and overall plant health.
Sunrose thrives in lean soil and generally needs little to no fertilization. If the soil is particularly poor, a light application of a balanced fertilizer in spring may be considered. Avoid high-nitrogen fertilizers, which promote excessive foliage growth at the expense of flower production.
Prune after the main flush of blooms in late spring to early summer. Shearing the plant back by one-third to one-half its size encourages a second wave of flowers and helps maintain a neat, compact shape. This light shearing also improves the plant’s appearance and stimulates new growth. Trim any stems damaged during winter in early spring.
Winter Protection for Sunrose
Sunrose plants are hardy in USDA Zones 5 through 8, though some varieties may be less reliably hardy in colder Zone 5 areas. Good drainage during winter is important to prevent root rot from overly wet soil.
In Zone 5, apply a light layer of winter mulch, such as pine needles or evergreen boughs, around the plant’s base in December for insulation. Remove this mulch in spring when new growth appears. Avoid applying too thick a layer, as it can trap excessive moisture. Established sunrose plants are more resilient to winter conditions, but young plants may benefit from additional protection during their first cold season.