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How to Grow Cupflower — Nierembergia

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Nierembergia–commonly called Cupflower–bears open cup- or bell-shaped, sometimes tubular white or light blue flowers in summer. It can be spreading or upright in form with alternate leaves.

Nierembergia is usually grown as an annual; it is a perennial in mild-winter regions. Plants grow best where summers are cool. Where summers are hot, Nierembergia will need additional water and afternoon shade.

Nierembergia is a genus of more than 20 species; some are annuals and some are perennials. Most perennial species are frost tender but they are easily propagated and are often grown as annuals.

Nierembergia is a good choice to plant as bedding, as border edging, or in containers.

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Get to know Nierembergia

  • Plant type: Annual or short-lived perennial in Zones 7-10
  • Growing Zones and range: Zones 7 to 10
  • Hardiness: Frost tender; grow as a cool-season annual; in Zones 8-9 grow as a perennial
  • Height and width: 10 inches (25cm) tall and wide
  • Foliage: Delicate, threadlike 1/2 inch long leaves
  • Flowers: Open cup- or bell-shaped, sometimes tubular flowers
  • Flower colors: Blue, white, and violet
  • Bloom time: Summer into Fall
  • Uses: Edging or front of mixed borders, mass as bedding, containers
  • Common name: Cupflower
  • Botanical name: Nierembergia
  • Family: Solanaceae
  • Origin: Temperate South America

Where to plant Nierembergia

  • Grow Nierembergia in full sun in cool summer regions in Zones 3-6. Grow in part shade in hot summer areas of Zones 7-11.
  • Plant Nierembergia in humus-rich, well-drained soil.

Nierembergia uses

  • Use Nierembergia as bedding, as border edging, or in a container.
  • Nierembergia’s spreading, flowering habit suits it for window boxes or hanging baskets.
Cupflower, Nierembergia
Cupflower, Nierembergia

When to plant Nierembergia

  • Set established Nierembergia in late winter or in spring a week or two before the last frost date.

Planting and spacing Nierembergia

  • Space Nierembergia about 10 inches apart. Plant in a mass of 10 plants or more for best effect.

How to water and feed Nierembergia

  • Nierembergia needs ample moisture; keep the soil evenly moist.
  • Fertilize Nierembergia occasionally with an all-purpose fertilizer.

Nierembergia care

  • Mulch around Nierembergia to conserve soil moisture.
  • Cut Nierembergia back by one-third after flowering to prompt new blooms.

Nierembergia pests and diseases

  • Nierembergia is susceptible to aphids and whiteflies and can be damaged by slugs and snails.
  • Nierembergia can be infected by tobacco mosaic virus.

Nierembergia propagation

  • Sow seed in autumn for spring flowering.
  • Seeds germinate in 15 to 25 days at 70° to 75°F (21°-24°C). Seedlings can withstand frost; transplants can be set in the garden 2 ro 3 weeks before the last frost.
  • Take stem tip cuttings of tender perennials any time during summer.

Nierembergia varieties to grow

  • Nierembergia caerulea: upright branching perennial with downy stems; cup-shaped lavender-blue flowers bloom through summer; ‘Mont Blanc’ and ‘Violet Robe’ are favorite cultivars.
  • N. repens, white cup: creeping, mat-forming bears open bell-shaped yellow-centered white flowers; cultivar ‘Violet Queen’ produces rich purple flowers.
  • N. scoparia: shrubby perennial with numerous pale blue flowers that fade to white at the margins; blooms from midsummer into early autumn.

Nierembergia frequently asked questions

Q: What is the best way to grow Nierembergia from seed?

A: Start indoors in February or early March for early bloom. Seeds need 10 to 12 weeks to mature into flowering plants.

Q: How’s the best way to grow Nierembergia in the garden?

A: Plant nierembergia in full sun or light shade. Keep the soil just moist. Fertilize monthly with an organic soluble plant food.

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Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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