How to Grow and Care for Ranunculus Flowers

Ranunculus flowers captivate with their bright colors and layered, rose-like petals, making them popular for bouquets. These perennials bloom in shades of yellow, pink, orange, red, purple, and white, representing charm and attraction. Blooming from early spring to early summer, ranunculus thrive in full sunlight, well-draining soil, and warm temperatures. They can grow between two inches and two feet tall, but note that many ranunculus species are toxic to humans and pets.

Ranunculus Care

Ranunculus are easy to grow if planted correctly. Here are the main care requirements for growing most ranunculus flowers:

• Plant in full sun in well-draining soil.
• Keep the soil moist but not wet.
• Fertilize twice per month for improved bloom length.
• Remove dead flowers as needed.

Planting

The timing and technique for planting varies between growing zones:

• When to plant: In zones 7 through 10, plant corms in the fall for late winter/early spring blooms that come earlier and bloom longer than spring-planted corms. Protect the area from freezing temperatures with a low tunnel/frost cloth. In zones 4 through 6, plant pre-sprouted corms in spring.
• Where to plant: Plant the corms in an area with full sun, 2 inches deep in the soil and 9 inches apart from one another.
• How to plant:
• Four weeks before the last frost, soak the corms in a bucket of room-temperature water below 55 degrees Fahrenheit for 4 hours.
• Change the water every hour (or use a fish pump to aerate it).
• Fill a flat planting tray (with no holes) with 1 to 2 inches of lightly moistened grow mix.
• Place the soaked corms, tuberous fingers down.
• Cover with an inch of lightly moistened soil, then move to a cool, dark, dry space. Keep the soil slightly moist and check daily for mold, removing any rotting corms. Roots will form in about two weeks, and the corms will begin to sprout and are ready to plant.

Light

Plant ranunculus in an area that receives full sun or 6 to 8 hours of sunlight daily for successful blooming. Less sunlight will result in fewer blooms and less sturdy stems.

Soil

Place your ranunculus in well-draining, rich, loamy soil. If planted in clay-based soils, the tuberous corms may rot if they become waterlogged. Though, some native ranunculus (Ranunculus repens) fare better in wetter, heavier soils, like those along the edges of ponds.

Water

Keep the soil moist but not wet after planting, and continue watering as foliage and flowers appear. Gradually reduce watering when flowers fade and foliage yellows, particularly if you plan to store corms.

Temperature and Humidity

Keep good airflow between your ranunculus plants to prevent mildew and combat humidity. They prefer cooler spring temperatures (the 60s – low 70s). Once the heat and humidity of summer hit, they will not produce blooms and the foliage will die back.

Fertilizer

Fertilize bimonthly during the growing season for lasting blooms. Use a bulb fertilizer in loose, loamy soil before planting.

Types of Ranunculus

There are numerous species of ranunculus ranging from native wildflowers to cultivars bred for showy blossoms.

• R. carolinianus: Also called Carolina buttercup, a native winter annual or short-lived perennial found in low woods and damp thickets.
• R. flammula: Often called lesser spearwort or sagebrush buttercup, this native ranunculus has five-petaled, small, solitary yellow flowers and is found along lakeshores and other shallow water.
• R. repens: Creeping buttercup is a weedy perennial that spreads to 36 inches wide. Native to Europe and Asia, it has naturalized in temperate regions throughout most of the U.S. and Canada.
• R. asiaticus: A tuberous-rooted plant that blooms in late spring to early summer, the cup-shaped, poppy-like flowers of the oft-called Persian buttercup have distinctive purple-black anthers.
• R. asiaticus hybrids: These are the ranunculus flowers sold by florists. The tuberous corms available for home gardening are hybrids with specific qualities of stem length, size, color, and petal number per bloom.

Pruning

Ranunculus flowers should be deadheaded as needed, but require no pruning during the growing season. Once the foliage turns yellow and dies, it can be cut down to the ground. Native ranunculus can become weedy and require removal to prevent overspreading.

Propagating Ranunculus

The most common method of propagating ranunculus flowers is to divide the corm and any offsets at the end of the growing season.

1. After the foliage has yellowed and died, cut the plant down to soil level.
2. Dig up the corms carefully and shake or wash off the soil. Remove any dried leaves or stems that remain.
3. Use sharp garden shears to divide the small off-shoots (cormels) from the main corm.
4. Allow the corms to dry in a cool, dry place and store the dry tuberous roots dry at 50 to 55 degrees F (10-13 Celsius).
5. Plant in fall in mild areas, or soak the corms in room-temperature water and pre-sprout them from spring planting.
6. Plant corms with the tuberous roots facing down at a depth of 2 inches and space plantings 9 inches apart.

How to Grow Ranunculus From Seed

Most ranunculus flowers are grown from corms; however, it is possible to produce them from seeds. The seeds should be started indoors about 12 weeks before the average date of your last spring frost.

1. Fill a seed-starting tray with growing mix and water until the mixture is moist, but not standing in water.
2. Sprinkle ranunculus seed generously on top of the growing mix, then add a thin layer of seed-starting mix over the seeds. Press the soil down gently with your hand after you are done.
3. Place the seeds under a grow light and keep the tray at a temperature of 50 degrees Fahrenheit until they germinate in about 20 to 30 days.
4. Thin the plants when the seedlings are about 2 inches high and continue growing under the grow lights.
5. Transplant the seedlings into 2- to 3-inch pots and begin to harden off the seedlings when daytime temperatures are in the upper 40s. Bring the plants indoors at night or anytime frost threatens.
6. Plant in the garden when temperatures are reliably in the upper 50 to 60-degree Fahrenheit range.

Overwintering

If you live in hardiness zones 8 through 11, ranunculus corms can be left in the ground or in a container over the winter. However, if you live in a rainy area, the corms can become waterlogged and rot over the winter.

In zones 3 through 7, remove the corms from the ground or container, remove the soil, and allow the corms to dry. Overwinter the plants in a cool, dry location in a mesh bag at 50 to 55 degrees Fahrenheit.

Common Pest & Plant Diseases

While aphids can become a problem, there are no other specific pests that attack ranunculus. However, small mammals might eat the corms, so protect them with a physical barrier after planting if needed.

How to Get Ranunculus to Bloom

If given enough sunlight, ranunculus flowers will readily bloom. Make sure the plants are getting unfiltered sunlight for at least six hours per day. Plants started from seed may have fewer blooms until the second season.

Ranunculus flowers tend to bloom from March through May, but bloom time may vary by species and location. Once bloomed, ranunculus flowers produce many layers of petals in an almost rose-like structure. These flowers are available in many colors and offer a light, sweet fragrance.