How to Grow Ranunculus: The Complete Guide

Buttercup Ranunculus asiaticus
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Buttercup Ranunculus asiaticus: Look at the gorgeous peach-honey blooms! 

Photo Credit
Maria Paina
Botanical Name
Ranunculus asiaticus
Plant Type
Sun Exposure
Bloom Time
Flower Color
Hardiness Zone

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Learn how to plant, grow, and care for ranunculus.

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Nothing compares to a vase of home-grown ranunculus. With their layered petals, they appear soft, delicate, and luscious—but also have a study stem perfect for cut flowers. Plus, these fragrant, colorful beauties attract bees and pollinators. Learn how to plant, grow, and care for ranunculus bulbs.

About Ranunculus 

Ranunculus is a genus of hundreds of species, but the one we grow as a cut flower is Ranunculus asiaticus, and its various hybrids and cultivars. Their rose-like blooms of layered petals can be any shade from white to pinks, salmons, creams, yellows, oranges, reds, and purples. Big blooms often reach 4 to 5 inches across, and when harvested at the correct stage, vase life is fantastic.

You’ll often see the packaging say ranunculus “bulbs,” though they are technically “corms,” which are flat, thickened underground stems that are underground food stores. This is similar to gladiolus flowers, which also grow from corms.

The corms are planted in early spring in areas that aren’t winter-hardy (zones 4 to 7); they will then bloom in late spring to early summer for 4 to 6 weeks. In warm climates (zones 8 to 10), the corms are planted in the fall and bloom in early spring.

These cool-season flowers can be perennials or annuals. They are perennials in zones 8 to 10, where they can overwinter. Everyone else tends to treat them as annuals and plant more corms annually, similar to many other bulbs.

Bouquet of ranunculus flowers in pastel colors.
Bouquet of stunning ranunculus flowers. Credit: NewAfrica

Planting

You’ll need a spot with full sun, at least six hours daily, and more is better. If you live in a warmer climate, pick a location with some shelter from the sun in the hottest part of the day.

Good drainage is essential to prevent problems with rot on the corms. Light, loose soil with some compost worked in is perfect. When planting in containers, use a high-quality potting mix and be mindful of the drainage.

When to Plant Ranunculus 

Ranunculus are planted at different times, depending on your situation. For gardeners in USDA zones 8 tp 10, the corms can be planted outside in autumn for early spring blooms. The benefit of planting in fall is they will bloom earlier than spring-planted corms and possibly for longer.

If you live in zone 7 or colder, you’ll need to either plant them by early spring or use a protected structure like a hoop house. Some home gardeners will grow them in containers to control their light and soil moisture. Flower farmers grow ranunculus in a greenhouse. 

The trick with planting ranunculus corms is to pay attention to the weather patterns in your area and plan accordingly. Planting them too late is the most common error. Also, remember: corms must not freeze. While the plants can tolerate a touch of frost, frozen corms will rot when they thaw.

For those planting in spring, start the pre-sprout process (see below) about four weeks before your last frost date.

How to Plant Ranunculus

Ranunculus corms are hard and dry when stored. Unlike a typical daffodil or dahlia bulb, these things can look and feel a bit dead, but they’re not. While pre-sprouting isn’t necessary, you’ll get flowers about three weeks earlier than if you just plunk them in the ground.

Before planting or pre-sprouting, soak ranunculus corms in cool water for 3 to 4 hours. Don’t soak longer than four hours. The corms will swell as they absorb water

To pre-sprout ranunculus:

  • Sort through and discard any corms which appear to be rotting or decaying.
  • Fill a seed starting tray with about an inch of moist–but not wet–potting mix.
  • Lay out the corms in the tray, spaced quite closely together. They can be almost touching. The corms should be right-side up so they look like they might crawl away.
  • Cover the corms with an inch or less of moist potting mix.
  • Place the tray in a cool, dark location. An unheated basement or garage might be perfect, as long as it’s dark. Fifty degrees is about perfect.
  • In about ten days, small white roots should be visible, indicating they’re ready for planting.

To plant ranunculus corms:

  • Prepare the bed by loosening the soil and working in a generous layer of compost.
  • Plant individual corms about 8-10 inches apart and about 2 inches deep. Remember to plant them with the “claws” pointing down so they look like they might skitter away.
  • If a spell of cold weather and frosty temperatures occurs, cover them with frost cloth.

*** Ranunculus are quite susceptible to powdery mildew. To maintain good airflow and circulation around the plants, avoid overcrowding them.

Growing

Ranunculus like cool weather and may benefit from some shade cloth if temperatures in your area get hot before they bloom. They love weather cooler than 70℉.

Use a drip-line type system to keep them evenly watered and water from below, if possible. If watering by hand, apply water at the base of the plant and attempt to avoid wetting the leaves.

Harvesting

Harvesting ranunculus is similar to peonies. You’re looking for buds starting to show color, and the main bud (if there is more than one on the stem) should feel a bit soft, like a marshmallow, not hard, like a marble. 

Properly harvested and treated, ranunculus blooms are famous for their long life in the vase, easily lasting ten days.

  • Cut individual stems deeply to encourage more long-stemmed blooms.
  • Remove foliage lower down that would be in the water.
  • Place cut stems immediately in water and enjoy!
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Wit and Wisdom

  • Ranunculus likes cool weather and will shut down as the temperature heats up towards 80℉. If you’ve grown ranunculus in the past but not gotten blooms, try planting them earlier in spring to give them more time in the cool weather.
  • Ranunculus corms can be dug and stored over winter, just like dahlias. Wait until the foliage has died back to dig them up. Shake the soil, let them dry, and then tease apart the individual corms, being careful to avoid breaking any of the “tentacles.” Store cool and dry until pre-sprouting time.
A vibrant bouquet of pink ranunculus flowers
The tightly layered petals create a stunning visual texture! Credit: dhirajbhudiya

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About The Author

Andy Wilcox

Andy Wilcox is a flower farmer and master gardener with a passion for soil health, small producers, forestry, and horticulture. Read More from Andy Wilcox