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.
These gorgeous flowers are beloved for their brilliantly colored double-ruffled petals, tall stems, and long vase life. Their color range, from deep pink and apricot to cream and pale yellow, make them a favorite at florist shops and in wedding bouquets.
ln warmer climates, ranunculus can be planted outdoors in fall with minimal protection. In colder areas where temperatures dip well below freezing for extended periods, wait to plant the tubers in late winter or early spring (once the threat of frost has passed) or start them indoors in pots about eight to 12 weeks before the average last frost. It takes about 90 days after planting to see blooms: Corms planted in fall bloom in early spring and continue for six to seven weeks, while those planted in late winter will flower by mid-spring and continue for four to six weeks. The bulbs are easy to find at nurseries and in catalogs.
- Botanical Name: Ranunculus asiaticus
- Common Name: Ranunculus, Persian buttercup
- Plant Type: Perennial flower
- Mature Size: 10 to 24 inches tall
- Sun Exposure: Full sun
- Soil Type: Loamy
- Soil pH: 6 to 6.5
- Bloom Time: Spring and summer
- Flower Color: White, pink, yellow, purple and red
- Hardiness Zones: 8-11, USDA
- Native Area: Mediterranean
How to Grow Ranunculus Flowers
Choose tubers labeled jumbo, which average eight centimeters in circumference, for the most flower stems per bulb. You can 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.
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.
If you have a large cold frame or small hoop house, you can grow ranunculus bulbs in zones 6 or 7 by providing protection, such as a cool winter greenhouse, when a hard freeze is expected.
Cut the flowers when they first begin to show color for long-lasting bouquets.
Plant the tubers in full sun with the claw end pointing down, and cover them with an inch of soil. For indoor container plantings, choose a south-facing, sunny window. Both roots and plants emerge from the top of the clump, not from the tips of the claws.
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.
It's not necessary to soak the tubers in water prior to planting but if you decide to soak, don't overdo it: an overnight soak will be enough to allow the corms to swell without encouraging mold growth. Water the bulbs well upon planting, then withhold water until growth appears to avoid rot. Once the plants are established, water sparingly throughout their period of growth. When flowers are finished, many gardeners remove the spent plants, as they perennialize poorly in most areas.
Temperature and Humidity
You could say that the ranunculus is the quintessential British flower, as they thrive in that cool weather sweet spot of about 55 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. If you are starting ranunculus indoors, avoid overheated rooms; temperatures above 65 F may inhibit growth.
Prepare the planting area with a layer of compost or mulch, then choose a fertilizer intended for bulbs. You'll probably only need about half-strength for these delicate flowers. Water the prepared area before planting.
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 yellow picotee flecked with red
- 'Merlot': Ivory flowers feathered with rose edges
Being Grown in Containers
Gardeners in temperate (cold weather) climates can grow ranunculus as container specimens. Use containers with a drainage hole at the bottom. Fill the container with good-quality, well-draining potting mix. Space the bulbs three to four inches apart and plant them about two inches deep in the container. Water after planting, and place the container where it will receive full sun all day.