Nemesia is a popular flowering plant known for its abundant, vibrant blooms. These plants display a wide spectrum of colors, including white, red, pink, blue, orange, yellow, and various bicolors. Some varieties also offer a delightful fragrance, often described as sweet, fruity, or vanilla-like, which can become more noticeable in the evening. Gardeners frequently incorporate Nemesia into borders, containers, and hanging baskets due to its compact growth and vibrant display.
Nemesia’s Growth Habit
Nemesia is generally cultivated as an annual plant in most climates. An annual germinates, grows, flowers, produces seeds, and then dies within one year. Conversely, a perennial lives for more than two years, often returning each spring from its established root system.
While often grown as an annual, Nemesia is technically a tender perennial. Meaning, under specific environmental conditions, particularly the absence of frost, the plant can survive for multiple years. Its perennial nature depends on the specific Nemesia species or hybrid. For instance, Nemesia strumosa is a true annual, while Nemesia caerulea is a tender perennial.
Climate and Cultivar Influence
Nemesia is generally hardy in USDA Plant Hardiness Zones 9 and above, extending up to Zone 11 for some varieties. In these warmer zones, where temperatures rarely drop below freezing, Nemesia can often survive winter outdoors and return the following spring.
Nemesia will not survive a hard frost. In regions with colder winters, it perishes after the first significant frost, requiring annual treatment. In frost-free areas, Nemesia can even thrive as a winter annual, providing blooms during cooler months. Modern Nemesia cultivars have improved characteristics, including greater heat tolerance, allowing them to bloom longer in warmer southern climates.
Practical Gardening Considerations
In most climates with cold winters, Nemesia is best planted in spring after all danger of frost has passed. As seasonal bedding plants, they provide continuous vibrant color from spring through fall, until the first hard frost. Regular removal of spent flowers, known as deadheading, promotes continuous blooming throughout the growing season.
For gardeners in suitable USDA hardiness zones (9 and above), overwintering Nemesia is an option. Container-grown Nemesia can be moved indoors to a frost-free location, such as a garage, basement, or a cool room, before winter temperatures arrive. Before moving indoors, cutting back foliage to a few inches prepares the plant for dormancy. During this dormant period, water sparingly to prevent root rot.