How to Grow and Care for Ranunculus Flowers

Ranunculus flowers, of genus Ranunculus, are beloved by florists and gardeners for floral arrangements, offering a rainbow of colors, including yellow, pink, orange, red, purple, and white. The various species in this genus require similar care: plenty of sunlight, well-draining soil, and warm weather.

Most flowers from the genus Ranunculus have a level of toxicity that is harmful to people and pets.

Ranunculus Care

Ranunculus are easy to grow if planted correctly. The specifics of some species may vary, but broadly, here are the main care requirements for growing most ranunculus flowers:

• Choose a sunny spot, ideally that gets six hours of sunlight or more each day.
• Prepare well-draining, nutrient-rich soil.
• Keep the soil moist but not wet.
• No additional fertilization is required, since ranunculus flowers have a short growing season.

Planting

The timing and technique for planting corms varies, depending on growing zones. Ranunculus corms are extremely cold-sensitive and must be protected from freezing temperatures. In zones 7 through 10, plant corms in fall for late winter/early spring blooms that come earlier and usually bloom a few weeks 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. About 4 weeks before the last frost date, soak the corms in a bucket of room-temperature water, not warmer than 55 degrees Fahrenheit. Change the water every hour (or use a fish pump to aerate the water), soaking for a total of 4 hours.

Fill a flat bottomed planting tray (without drainage holes) with 1 to 2 inches of lightly moistened grow mix. Make sure the mix is not wet, as too much moisture can cause the corms to rot. Place the soaked corms with the tuberous fingers pointing down into the medium. Don't worry about spacing, as they'll only stay in the tray about two weeks. Cover the corms with an inch of lightly moistened soil.

Place tray in a cool, dark, dry space, like a basement. Keep soil slightly moist, and check daily for mold. Remove any rotting or moldy corms. Roots will form in about two weeks, and the corms will begin to sprout. The corms are ready for spring planting in the garden. Plant the corms 2 inches deep, 9 inches apart. If freeze is forecasted, cover the area with a frost cloth.

Light

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

Soil

Ranunculus species prized for their showy blooms must be planted in well-draining, rich, loamy soil. If planted in clay-based soils, the tuberous corms may rot if they become waterlogged.

Some native ranunculus (Ranunculus repens) fare better in wetter, heavier soils, like those along the edges of ponds. The genus name comes from the Latin word rana, meaning frog, because many species grow in damp places.

Water

Once corms are planted in the ground or a container, the soil should be kept moist but not wet. Continue watering as the foliage and flowers appear. Once the flowers are gone and the foliage has turned yellow, slow your watering schedule, especially if you plan to dig up the corms and store them for the next growing season.

Temperature and Humidity

Ranunculus flowers 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

Since ranunculus flowers have a short growing season, they do not usually require fertilization. Before planting the corms, a granular fertilizer recommended for planting bulbs can be worked into the loose, loamy soil.

Types of Ranunculus

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

• R. carolinianus: Commonly 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 produces five-petaled small solitary yellow flowers on slender, creeping stalks and is found along lakeshores, pond margins, and other shallow water.
• R. repens: Creeping buttercup is a weedy perennial around 8-12 inches tall, but spreads to 36 inches wide. Native to Europe and Asia, this plant has naturalized in temperate regions throughout most of the U.S. and Canada.
• R. asiaticus: A tuberous-rooted plant with parsley-like leaves that blooms in late spring to early summer. Often called Persian buttercup, the cup-shaped, poppy-like flowers (to 2-inches diameter) have distinctive purple-black anthers on stems typically growing 12-24 inches tall ranging from red, pink, purple, yellow, to white.
• R. asiaticus hybrids: The ranunculus flowers sold by florists and the tuberous corms available for home gardening are hybrids with specific qualities of stem length, size, color, and the number of petals on each bloom.
  

Pruning

Ranunculus flowers require no pruning during the growing season. Once the foliage turns yellow and dies, it can be cut down to the ground whether the corms will be left in the ground or removed.

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. The small plants can be transplanted outdoors when daytime temperatures are reliably in the upper 50-degree Fahrenheit range.

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, sprinkle a thin layer of the seed starting mix on top of the seeds, and press the soil down gently with your hand.
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. Store 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. Root rot will be an issue if the plant is overwatered or planted in clay soil.

How to Get Ranunculus to Bloom

If given enough sunlight, ranunculus flowers will readily bloom. Plants started from seed may have fewer blooms until their second season.

Bloom Months

Though bloom time may vary by species and location, ranunculus flowers tend to bloom from March through May.

What Do Ranunculus Flowers Look and Smell Like?

Ranunculus flowers tend to have many layers of petals in an almost rose-like structure. These flowers are available in many colors. They typically offer a light, sweet fragrance.

How to Encourage More Blooms

The most important factor in getting ranunculus flowers to bloom is sun. Make sure the plants are getting unfiltered sunlight for at least six hours per day.