Origin
Erysimum capitatum (Dougl. ex Hook.) Greene var. stellatum (J.T. Howell) Twisselmann, commonly known as the western wallflower, is a species of flowering plants belonging to the Brassicaceae family. This plant is native to North America and can be found in western North America, from British Columbia down to California and eastward to Wyoming.
Common Names
The western wallflower, Erysimum capitatum var. stellatum, is known by various common names, depending on the region. It is commonly referred to as the prairie rocket, sanddune wallflower, mountain rocket, or Dougl as wallflower.
Uses
Native Americans have used different parts of the western wallflower for various medicinal purposes. They used the roots to relieve digestive problems, crushed leaves for insect bites, and stems for arrow shafts. The plant also serves an ornamental purpose and is grown in gardens as an attractive flowering plant.
General Appearance
The western wallflower, Erysimum capitatum var. stellatum, is an herbaceous perennial plant that can grow up to a height of 1 meter, but typically grow between 20 and 50 centimeters. This plant has narrow, linear, and lance-shaped leaves that grow from a basal rosette and have hairy undersides. The flowers are bright yellow and have four petals that form a cross shape. The plant blooms from March to October depending on its location.
The western wallflower is an important source of food for pollinators such as bees and butterflies. Its large quantities of nectar attract these insects to pollinate the plant, helping it reproduce. The plant's high resistance to drought, cold, and grazing makes it an excellent addition to xeriscapes, low-water or low-maintenance landscaping.
Light Requirements
Erysimum capitatum var. stellatum typically requires full sunlight exposure to grow and thrive. It can survive in partially shaded areas, but the plant may not bloom as fully as it would in full sun. To ensure optimal growth and flowering, it is recommended to plant Erysimum capitatum var. stellatum in a location where it can receive at least 6 hours of direct sunlight daily.
Temperature Requirements
Erysimum capitatum var. stellatum grows well in climates with cool to moderate temperatures. It prefers temperatures ranging from 60 to 75 degrees Fahrenheit during the day and 45 to 55 degrees Fahrenheit at night. This plant is well-suited for regions with a Mediterranean climate, which typically has cool, wet winters and warm, dry summers. It may not perform as well in hot, humid climates or areas with severe temperature fluctuations.
Soil Requirements
This plant prefers well-draining, slightly acidic soil. It can grow in a variety of soil types, including clay, loam, and sand, but the soil should be amended with organic matter to improve water retention. Erysimum capitatum var. stellatum is adapted to grow in rocky, gravelly soils, which may help prevent waterlogged soils that could lead to root rot. However, excess dryness in the soil can negatively impact its growth. Therefore, it is important to keep the soil moist but not waterlogged, especially during periods of drought.
Cultivation
Erysimum capitatum var. stellatum is native to California and can grow in almost any soil type. However, it prefers well-draining soil that is slightly acidic to neutral. The plant is quite hardy and can tolerate both hot summers and cold winters, making it an excellent choice for USDA hardiness zones 5-9.
When planting this species, ensure that it is situated in an area with full sun. While it can tolerate some shade, it best performs in areas that receive at least six hours of direct sunlight each day. Planting should take place in early spring or late fall.
Watering Needs
While Erysimum capitatum var. stellatum does not require much water during periods of active growth, it still requires regular watering to maintain its appearance. During the hot summer months, it is recommended that the plant be watered once every week, with each watering session lasting about 30-60 minutes. During the colder months, watering should be less frequent, with a schedule of once every two weeks.
It is essential to note that the plant is susceptible to root rot, so it is important not to overwater. Soggy soil can cause the roots to die, resulting in the death of the entire plant.
Fertilization
Like other flowering plants, Erysimum capitatum var. stellatum can benefit from regular fertilization. Use a high-phosphorus fertilizer during the planting process, and then again in early spring. This will promote the growth of healthy blooms.
During the growing season, use a balanced fertilizer every four to six weeks. This will provide the plant with the necessary nutrients to maintain healthy foliage.
Pruning
Erysimum capitatum var. stellatum is a relatively low-maintenance plant that does not require extensive pruning. However, the plant can become somewhat leggy and scraggly in appearance if left unpruned.
To maintain a more compact and bushier appearance, prune the plant lightly after each blooming period. Remove any dead or damaged stems, as well as any flowers that have begun to fade. This will encourage the plant to produce new blooms and maintain a more attractive shape.
Propagation of Erysimum capitatum var. stellatum
Erysimum capitatum var. stellatum can be propagated through seeds, stem cuttings, and root division. The following are the detailed information on each propagation method:
Propagation through Seeds
Propagating Erysimum capitatum var. stellatum through seeds is the easiest method. Harvest the seed pods when they are mature. The pods will start to split and release seeds. Collect the seeds and dry them before sowing. Sow the seeds in late fall or early spring in a well-draining soil mix. Keep the soil moist and place them in a location that receives full sun. The seeds will germinate in 10-14 days.
Propagation through Stem Cuttings
Stem cuttings are another way to propagate Erysimum capitatum var. stellatum. Take 4-6 inch long cuttings from a healthy plant in the spring or early summer. Make a clean cut at a 45-degree angle and remove any lower leaves. Dip the cuttings in rooting hormone and plant them in a well-draining soil mix. Keep the soil moist and place them in a location that receives partial shade. The cuttings will root in about 4-6 weeks.
Propagation through Root Division
Erysimum capitatum var. stellatum can also be propagated through root division. Divide the plant in the early spring before new growth appears. Dig up the plant and separate the roots into multiple sections. Make sure each section has some healthy roots and leaves. Plant the divisions in a well-draining soil mix and water them thoroughly. Keep them in a location that receives partial shade until they become established.
Disease Management for Erysimum capitatum var. stellatum
Erysimum capitatum var. stellatum is generally not susceptible to many diseases, but there are some potential problems to look out for. Below are some common diseases that may affect the plant, along with tips on how to manage them effectively:
- Verticillium Wilt: This is a fungal disease that affects the plant's vascular system, causing leaves to wilt and turn yellow. It can spread quickly and cause severe damage. To control Verticillium Wilt, remove and destroy infected plants immediately. Avoid replanting in the same area for at least three years.
- Crown Rot: This is a soil-borne disease that attacks the plant's roots and causes stunted growth, yellowing leaves, and plant death. Affected plants should be removed immediately, and the soil in the area should be treated with a fungicide.
- Powdery Mildew: This fungal infection appears as a white powdery substance on leaves and stems. To control powdery mildew, ensure good air circulation around the plant and avoid over-watering. Fungicides may also be used as a preventative measure.
Pest Management for Erysimum capitatum var. stellatum
Although pests aren't a significant problem for Erysimum capitatum var. stellatum, here's a list of the most common pests that may affect the plant and some ways to effectively manage them:
- Aphids: These are small, soft-bodied insects that feed on a plant's sap and cause leaves to curl and become yellow. They can be controlled through regular washing with water and insecticidal soap spray.
- Spider Mites: These pests are tiny and difficult to detect until their feeding damage shows on the foliage and plant health. To control spider mites, isolate infected plants, encourage humidity around the plant, and apply insecticidal soap or a miticide when necessary.
- Slugs and Snails: These pests feed on the leaves and stems of the plant, leaving large holes. To manage slugs and snails, remove debris and loose soil from around the plant and place a barrier around it using copper strips, diatomaceous earth, or grit. You can also trap them with beer traps.
