How to Plant and Grow Nierembergia

A tender perennial, nierembergia, also known as cupflower, is commonly grown as an annual. Its adorable cup-shaped flowers with yellow centers and its neat, compact growth habit make it a useful plant for everything from containers to edging. Nierembergia is native to Argentina. The heat tolerance depends on the variety so if your summers are hot, pick one that thrives in high temperatures.

The plant is valued for its long bloom period from early summer through early fall. The small narrow leaves retain their attractive green color throughout the season and the color of its flowers holds up well even in the brightest sun.

Where to Plant Nierembergia

Choose a location with full sun and well-draining soil that is slightly acidic to neutral.

In the landscape, nierembergia looks best in a mass planting. Plant it in rows along the front of beds or borders or plant it in groups in rock gardens.

Nierembergia also makes an excellent filler plant for containers, hanging baskets, and window boxes. With its medium height, it visually ties together taller plants and cascading plants.

How and When to Plant Nierembergia

Plant nursery-grown potted plants in the spring after there is no more danger of frost. Harden the plants off before transplanting.

Dig a hole about twice the size of the nursery pot and just as deep. Place the plant in the center of the hole and backfill with original soil. Tamp it down and water it immediately. Continue to water until the plants are established. Apply mulch around the base of the plant to retain soil moisture. Young plants initially grow slowly but growth picks up after transplanting.

Space plants 12 inches apart.

Nierembergia Care Tips

Some basic care throughout the summer is needed to keep looking nierembergia at its best.

Light

Generally, nierembergia thrives in full sun although less heat-tolerant varieties do better with some afternoon shade.

Soil and Water

The soil should be rich in organic matter and well-drained. A pH between 6.6 and 7.5 is ideal but nierembergia is quite adaptable to different levels of soil acidity.

Although nierembergia tolerates dry conditions, it does better with consistent moisture so water as needed in the absence of rain.

Temperature and Humidity

Nierembergia is not winter-hardy below Zone 7 and is commonly grown as an annual. The bloom period ends with the first fall frost.

Fertilizer

Fertilize the plant with a complete all-purpose garden fertilizer, either a slow-release granular fertilizer or, if the plant starts to look a little tired as summer progresses, a water-soluble fertilizer to give it a quick nutrient boost.

Pruning

Removing dieback and deadheading spent flowers helps to keep the plant looking tidy and extend its bloom period.

Potting and Repotting Nierembergia

Nierembergia makes an excellent container plant. Use a pot with large drainage holes and fill it with well-draining, rich potting soil. keep in mind that potted plants need more frequent watering and fertilization than plants in the landscape.

As the plant is usually grown as an annual, its life cycle ends in the fall and repotting won't be necessary during its single growing season.

Pests and Problems

The plants are not prone to serious pests or diseases. You might find slugs and snails feeding on the plants, especially young plants.

How to Propagate Nierembergia

Nierembergia is easy to propagate from seed. Start the seeds indoors 8 to 10 weeks before your last average frost date. Place the seeds on top of pots filled with soilless potting mix and barely cover them, as they need light to germinate. Keep the seeds evenly moist. At a temperature around 70 degrees F., germination takes 2 to 3 weeks.

Place the seedlings in a window with plenty of bright direct sunlight or under grow lights. Harden seedlings off and transplant them outdoors after the last spring frost.

Types of Nierembergia

'Augusta Blue Skies' Nierembergia

Nierembergia 'Augusta Blue Skies' is a heat- and drought-tolerant hybrid with lavender-blue flowers all summer long. It grows 8 to 12 inches tall and wide.

'Blue Eyes' Nierembergia

Nierembergia 'Blue Eyes' bears silvery lilac-blue flowers with darker veins on a 10-inch-tall plant.

'Mont Blanc' Nierembergia

Nierembergia scoparia 'Mont Blanc' is an All-America Selection winner with pure-white flowers. It grows 6 inches tall and spreads 12 inches.

'Purple Robe' Nierembergia

Nierembergia scoparia 'Purple Robe' is a compact variety with violet-blue flowers. The plant grows 6 inches tall and spreads 12 inches.

'Starry Eyes' Nierembergia

Nierembergia gracilis 'Starry Eyes' has white cup-shaped flowers with lavender centers and yellow eyes. This cultivar does especially well in hot and humid summers. This cultivar grows 10 to 16 inches tall and 18 inches wide.

Nierembergia Companion Plants

Angelonia

A tough perennial, angelonia stands up against summer's heat and humidity with no problem, making it a hearty and colorful addition to any sunny spot. Most angelonia plants grow upright with spires of flowers and deep green, glossy foliage. Erect spires of angelonia fit nicely into the middle of a bed or border. This South American native loves lots of sun and damp soil. It is hardy in USDA zones 9–11 and is grown as an annual in cooler climates.

African Marigold

The large, pom-pom blooms of African marigolds are perfect for garden beds, path edges, and containers where sunlight is plentiful. These easy-to-grow annuals come in a warm color palette including creamy white, yellow, orange, and rusty red, African marigolds add a welcome infusion of color all season long. Even without the blooms, they have attractive deep green foliage.

Bidens

With prolific blooms of orange, gold, pink, white, or red, bidens look like a colorful floral waterfall. These tough annuals (or short-lived perennials in zones 8-11) are commonly grown as a trailing or groundcover plant but are also available in more upright types that work as bedding plants.

Garden Plans For Nierembergia

Drought-Tolerant Landscape Plan

The drought-tolerant perennials, annuals, trees, and shrubs in this drought-tolerant landscape plan provide plenty of colorful flowers and lush foliage throughout the growing season. Plus, this design uses the trick of planting everything close together to make sure there's no open ground that will dry out faster in the summer sun. You can also complement the planting with a fountain or pool, which will add a cooling effect no matter how hot and dry the weather gets.