How to Grow Ranunculus Flowers

Field of assorted buttercup (Ranunculus) flower species.

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If flowering bulbs are one of nature’s mysteries, watching the claw-like tuber of a ranunculus produce three dozen rosette-shaped flowers must be one of nature’s miracles. For sheer petal count, it’s hard to top the ranunculus, also known as the Persian buttercup. If you’ve seen them in flower arrangements, you’ve probably been tempted to flick your thumb across the flower’s surface as one would rifle through a voluminous book; however, this would bruise the tissue-paper-thin petals of these delicate beauties.

Ranunculus flowers are popular as wedding flowers, as they are inexpensive, showy, and long lasting as cut flowers. Learn how to cultivate these Mediterranean natives in your landscape or container garden for beautiful flower arrangements.

Where and When Do Ranunculus Flowers Grow?

You could say that the ranunculus is the quintessential British flower, as they thrive in that cool weather sweet spot of about 55 degrees F. For the rest of us, ranunculus will grow outdoors in zones 8 to 11 as fall planted bulbs. However, there's a catch: the plants fare poorly in the deep South, as they really need those cool summers to thrive. Therefore, many turn to container gardening to gain control over growing conditions. Gardeners in temperate (cold weather) climates can also grow ranunculus as container specimens. If you have a large cold frame or small hoop house, you can grow ranunculus bulbs in zones 6 or 7 by providing protection when a hard freeze is expected.

The blooming time of ranunculus flowers varies depending on when the tubers are planted. Fall plantings of ranunculus come into bloom in March, while spring plantings will flower in late summer. Either way, if the weather is dry and mild, the blooms may last for up to six weeks. 

Ranunculus Planting

Choose tubers labeled jumbo, which average eight centimeters in circumference, for the most flower stems per bulb. You may expect to see as many as three dozen flowers born on 18-inch stems from these bulbs. Number two and number three bulbs are fine for planting groups of a dozen or more outdoors.

In spite of the tubers’ wizened appearance, it isn't absolutely necessary to soak them in water prior to planting. If you do decide to soak, don't overdo it: an overnight soak will be enough to cause the corms to swell, without encouraging mold growth.

If you have heavy soil, amend with peat moss or plant in raised beds. An application of bone meal at planting time is fine, but not necessary for ranunculus tubers treated as annuals.

Plant the tubers in full sun with the claw end pointing down, and cover them with an inch of soil. Choose a south-facing, sunny window for indoor container plantings. Both roots and plants emerge from the top of the clump, not from the tips of the claws. Water the bulbs well upon planting, then withhold water until growth appears to avoid rot. Growing ranunculus flowers from bulbs in a container works best for those who can maintain a cool winter greenhouse. This provides the combination of bright sun and temperatures between 45 and 60 F that make ranunculus thrive. Avoid overheated rooms for starting ranunculus; temperatures above 65 degrees F may prevent growth.

Ranunculus Care

Water ranunculus plants sparingly throughout their period of growth. When flowers is finished, many gardeners remove the spent plants, as they perennialize poorly in most areas. If you live in zones 8 to 11 and wish to try growing the plants as perennials, leave them in place and allow the foliage to die back naturally at summer’s end. Dormant tubers appreciate dry, cool conditions; too much moisture and warmth will cause rot.

Ranunculus Design Tips

As ranunculus flowers thrive in cool conditions, gardeners should look to other cool weather loving annuals and perennials to pair with these flowers. Pink and orange ranunculus flowers pop against blue pansies. Yellow snapdragons and orange or red ranunculus make cheerful companions in early spring container gardens.

Recommended Ranunculus Varieties

Two strains of ranunculus are common in the nursery trade: Tecolote and Bloomingdale. Most people are partial to Tecolote ranunculus tubers for the large, five-inch flowers they can produce. Today’s fluffy doubles are largely the result of the breeding efforts of Edwin Frazee of The Flower Fields in Carlsbad, California. In addition to vivid solid colors of white, pink, yellow, salmon, purple, and red, look for these exceptional Tecolote varieties:

  • Café: Bronze blooms
  • Flamenco: A picotee yellow flecked with red
  • Merlot: Ivory flowers feathered with rose edges