Wallflowers (Erysimum) bring vibrant color and a delightful fragrance to garden spaces, signaling the arrival of spring and often continuing their display into summer. Their diverse palette, ranging from sunny yellows to rich purples, adds visual appeal to borders, rock gardens, and containers. These resilient plants are a popular choice for gardeners seeking to enhance both the look and aroma of their outdoor areas.
Understanding Wallflowers
Wallflowers belong to the genus Erysimum, a member of the Brassicaceae family. These plants are characterized by their four-petaled flowers, often appearing in clusters or spikes. Their blooms emerge in spring and can continue through summer, with some varieties offering extended flowering periods. Many species boast a sweet fragrance, attracting pollinators like bees and butterflies.
Erysimum encompasses annuals, biennials, and herbaceous perennials. Annual wallflowers complete their life cycle within one growing season, biennials grow foliage in the first year and flower in the second, while perennials can persist for several years. This diversity allows gardeners to select types best suited for their climate and garden.
Planting and Growing Conditions
Wallflowers thrive in full sun, which promotes optimal blooming and helps minimize fungal issues. In warmer climates, providing some afternoon shade can protect them from intense heat. These plants require well-drained soil, as they are susceptible to root rot in soggy conditions.
An ideal soil pH for wallflowers ranges from neutral to slightly alkaline, between 7.0 and 9.0. They can tolerate poor to moderately fertile soil, and their ability to grow in cracks in walls gives them their common name. Planting times vary by type; biennial wallflowers are sown in late spring to early summer for blooms the following spring, while perennial varieties can be planted any time of year, with spring being ideal. Space individual plants about 10 to 12 inches apart for proper air circulation and growth. After planting, water new wallflowers thoroughly to help them settle.
Ongoing Care for Wallflowers
Wallflowers are drought-tolerant and do not require frequent watering, especially once mature. Container-grown wallflowers, however, will need more regular watering as their soil dries out more quickly. During prolonged dry periods, particularly when flowering, supplemental watering may be necessary.
Wallflowers do not require heavy fertilization. Mixing compost into the soil during initial planting can provide sufficient nutrients. For container plants or if growth appears weak, a liquid organic fertilizer can be applied when new growth begins in spring, or a balanced water-soluble plant food monthly.
Deadheading, which involves removing spent blooms, encourages continuous flowering and prevents the plant from expending energy on seed production. Pruning helps maintain a bushy shape and prevents leggy growth. After the main bloom period, or in early spring for warm climates, stems can be trimmed back by at least half. In colder regions, pruning in the fall to a few inches above the soil promotes dense new growth in spring.
Popular Wallflower Varieties
Erysimum ‘Bowles’s Mauve’ is a widely recognized perennial wallflower, valued for its long blooming period from mid-spring through fall and its striking rich mauve flowers. This variety features attractive gray-green foliage that often remains evergreen in milder climates and can reach heights of 1 to 3 feet.
Another notable group includes the ‘Winter’ series, such as ‘Winter Orchid’ and ‘Winter Sun’. ‘Winter Orchid’ produces fragrant spikes of coppery-orange flowers that transition to magenta-pink, blooming from late winter into early spring. ‘Winter Sun’ offers fragrant, golden-yellow blooms. These varieties are appreciated for their compact, mounding habits and vibrant colors. Other varieties include ‘Sunset Apricot’ with fragrant yellow-apricot flowers, and ‘Persian Carpet’ which boasts multi-colored fragrant blooms in shades of gold, cream, red, purple, and orange.
Troubleshooting Wallflower Problems
Pests like aphids, flea beetles, and cabbage worms may affect wallflowers, similar to other members of the Brassicaceae family. Aphids can cause distorted leaves and poor growth, while flea beetles create small holes in foliage. Inspecting plants regularly helps in early detection, and introducing beneficial insects or using organic insecticidal soaps can manage infestations.
Fungal diseases, such as powdery mildew and root rot, are common problems. Powdery mildew appears as a white, dusty coating on leaves, often occurring in humid conditions or with poor air circulation. Ensuring proper plant spacing and avoiding overhead watering helps prevent its spread.
Root rot, caused by overly wet soil, leads to wilting and yellowing leaves. This issue is avoided by planting in well-draining soil and not overwatering. If leaves turn yellow, it can indicate overwatering, nutrient deficiencies, or even natural aging. Addressing soil drainage and considering a soil test for nutrient imbalances can resolve yellowing foliage.