Nemesia belongs to the botanical genus Nemesia, which falls within the family Scrophulariaceae, commonly known as the figwort family. This family is notably diverse, encompassing over 60 species of Nemesia alone, characterized by their annual, perennial, or sub-shrub growth habits. The genus is known for its colorful, two-lipped flowers, which structurally resemble snapdragons, with each flower having an upper lip composed of four lobes and a lower lip with two lobes.
The history of Nemesia as a cultivated plant traces back to its use as an ornamental in gardens, particularly due to its vibrant and varied coloration. Cultivation began with the species native to southern Africa, where they have been appreciated for many years for their aesthetic charm. Over time, numerous hybrids have been developed, primarily focusing on enhancing color variety, bloom size, and extending the flowering season. These hybrids have made Nemesia a popular choice for gardeners looking to add a splash of color to their landscapes, especially as bedding plants or in containers.
Nemesia is native to southern Africa, specifically thriving in the sandy coasts or disturbed grounds of the region. This habitat preference reflects the plant’s natural ability to grow in well-drained, often sandy or gravelly soils under sunny conditions. The diversity within the genus is largely concentrated in South Africa, where the climate supports their growth, with mild winters and warm, sunny summers that are ideal for these cool-weather lovers.
In terms of USDA Hardiness Zones, Nemesia’s suitability varies by species and cultivar. The most popular species, Nemesia strumosa (Pouch Nemesia), and Nemesia caerulea, are typically treated as cool-weather annuals in zones where they cannot survive the winter. Nemesia strumosa can be grown in USDA zones 2 through 10 when cultivated as a cool-weather annual, thanks to its adaptability to various climates when the temperature is moderate. However, Nemesia caerulea is a tender perennial that is winter hardy to USDA Zones 9-10 but is often grown as an annual in colder regions. For optimal growth in these zones, Nemesia prefers cooler temperatures, blooming best in early spring or fall, with performance declining in the heat of summer in zones lower than 9. Thus, gardeners in warmer zones (9 and 10) can enjoy Nemesia as a perennial, while those in cooler zones will plant them anew each year for their delightful spring and fall displays.
Nemesia Plant: Characteristics
- Size: Nemesia plants vary in size depending on the species and cultivar. As bedding plants or in containers, they typically grow to a height of 6 to 24 inches (15 to 60 cm) with a similar spread. Some varieties can be more compact, suitable for hanging baskets or small pots, while others might grow taller and bushier for garden borders.
- Growth Rate: Nemesia is known for its relatively fast growth rate, especially when conditions are favorable. From seed to flower, under ideal conditions, it can take about 6 to 12 weeks. Once established, they grow quickly, especially in cooler temperatures, which encourage vigorous growth and blooming.
- Leaves: The leaves of Nemesia are generally lance-shaped to oval, with a somewhat serrated edge. They are medium to dark green, sometimes with a slight fragrance, and are arranged oppositely on the stems. The foliage is not particularly dense, allowing the flowers to be the main feature of the plant, but it’s lush enough to create a nice backdrop.
- Flowers: Nemesia flowers are one of its most attractive features, offering a wide range of colors including white, pink, purple, blue, yellow, and various bicolors. The blooms are small, typically about an inch across (2.5 cm), with a two-lipped structure reminiscent of snapdragons. Each flower has an upper lip with four lobes and a lower lip with two, often with a contrasting or darker center to attract pollinators.
- Bloom Time: Nemesia is celebrated for its long blooming period, particularly in cooler climates. They can start blooming in early spring and continue into late fall if temperatures remain moderate. In warmer zones, they might pause during the hottest months but can resume blooming when the weather cools again. In general, they provide color for several months, with peak bloom in spring and possibly a second flush in autumn.
- Lifespan: Most Nemesia cultivated in gardens are treated as annuals in cooler climates where they do not survive winter. However, in USDA Zones 9-10, some species like Nemesia caerulea can act as perennials, potentially living for several years if conditions are right. The lifespan of an individual plant, when grown as an annual, is one growing season, but they can self-seed, allowing for natural regrowth in subsequent years.
- Fragrance: Many Nemesia varieties have a pleasant, slightly sweet or spicy scent, which adds to their appeal in garden settings. This fragrance can be more pronounced in the cooler parts of the day, making them excellent for areas where their scent can be appreciated up close, like patios or near pathways.
Nemesia Plant: Cultivation
Soil
- Nemesia thrives in well-drained, fertile soil. A soil mix that includes sand or perlite can help with drainage, as these plants do not like to sit in wet conditions.
pH
- They prefer a slightly acidic to neutral soil pH, ranging from 6.0 to 7.0. Testing and amending the soil if necessary can ensure optimal growth.
Sunlight
- Most varieties require full sun for best flowering, although they can tolerate some afternoon shade in hotter climates. About 6 hours of direct sunlight per day is ideal.
Watering
- Regular watering is crucial, especially when plants are young or during dry spells. However, overwatering should be avoided to prevent root rot. Water at the base of the plant to keep foliage dry and reduce disease risk.
Temperature
- Nemesia prefers cooler temperatures, performing best between 40°F to 75°F (4°C to 24°C). They can struggle in temperatures consistently above 80°F (27°C), where blooming might decrease.
Planting
- Plant Nemesia after the last frost date for your area if starting from seedlings. For seeds, they can be sown indoors 6-8 weeks before the last frost or directly in the garden after the soil has warmed slightly in spring.
Spacing
- Space plants about 6 to 12 inches apart in the garden or containers, depending on the variety’s mature size. This ensures good air circulation and reduces competition for nutrients.
Fertilization
- Use a balanced, slow-release fertilizer at planting time, or apply a liquid fertilizer every couple of weeks during the growing season. However, too much nitrogen can lead to lush foliage at the expense of flowers.
Deadheading
- Regularly remove spent flowers to encourage more blooms. This process, known as deadheading, can significantly extend the flowering period.
Pest and Disease Control
- Keep an eye out for common pests like aphids, spider mites, and slugs. Good air circulation and avoiding overhead watering can prevent fungal diseases. If issues arise, treat with appropriate organic or chemical controls.
Propagation
- Nemesia can be propagated by seed, cuttings, or division. Seeds should be sown in a light, well-draining seed-starting mix. Cuttings from non-flowering stems can root in a similar mix. Division can be done in spring with mature clumps.
Winter Care
- In zones where Nemesia is not hardy (below USDA Zone 9), treat them as annuals or take cuttings to overwinter indoors. In warmer zones, mulching around perennials can help protect them during cooler months. If grown in containers, moving them to a sheltered area or indoors can extend their life.