How to Grow Ranunculus (5 Growing Tips)

By: Angela Judd | October 9, 2024

When I first saw the gorgeous blooms on ranunculus flowers, I didn’t think growing them here in the low desert of Arizona was possible. I’m glad I was wrong. Learning how to grow ranunculus is easier than you think.

The stunning rose-like blooms with tissue-thin petals almost don’t look real. Ranunculus blooms come in nearly every color on tall stems. With these five tips, learn how to grow ranunculus (even if you live in a hot summer climate like the low desert of Arizona).

5 Tips for How to Grow Ranunculus

1. Plant ranunculus at the right time

Ranunculus grows best in spring-like temperatures of about 55°F with plenty of sunlight.

In zones seven and warmer, there are two planting windows — late fall and again in late winter or early spring. For zones cooler than zone 7, plant in the spring after the danger of frost is passed.

In the low desert of Arizona, plant ranunculus corms from October to November and again from February to March (Presprout corms if planting in February – March).

The Perpetual Annual Flower Planting Calendar, available in my shop, helps you learn when to plant flowers in the low desert of Arizona and whether to plant seeds or transplants.

2. Soak corms before planting

Ranunculus are grown from claw-like ‘corms’ — a swollen underground plant stem that stores the nutrients for the plant until needed. Look for large corms, which have more stored energy and will grow larger with more blooms. I love the ranunculus corms from Easy to Grow Bulbs. If you receive the ranunculus bulbs before planting time, keep them somewhere cool and dry. I store mine in a hall closet. You can learn more about ordering bulbs for fall planting in this guide.

Soak the dry corms in tepid or room temperature water for 3 to 4 hours (not longer). Soaking the corms will often make them double in size. Don’t soak the ranunculus corms until you are ready to plant.

3. Plant ranunculus correctly

Ranunculus grows best in rich, healthy, well-draining soil with plenty of sunlight. Choose an area with full sun if possible. Add several inches of compost and a balanced organic fertilizer to the soil before planting. If planting in containers, use potting soil that is light and well-draining.

How to plant ranunculus bulbs: Plant 2-3 inches deep and about 6 inches apart. Plant the corms in the ground with the claws facing down. Fill the hole back in with soil and water well.

If you live in a wet climate, after planting ranunculus bulbs, you may not need to water again until sprouts appear. Too much moisture in the soil may cause the corms to rot.

In dry climates like the low desert, keep soil evenly moist but do not overwater to prevent the corms from rotting.

For square foot gardening, plant four corms per square foot.

4. Care for growing ranunculus

Overall, ranunculus plants are easy to grow and pest and disease-resistant.

Ranunculus needs plenty of sunlight to grow well. Ranunculus grows best in moist soil but does not like overwatering. If soil is not well-draining, ranunculus corms often rot.

SPECIAL NOTE: All parts of ranunculus are poisonous when ingested. The plant sap may cause skin irritation. Poison is not residual in the soil; only the plant is poisonous.

5. Enjoy ranunculus blooms

Corms planted in the fall typically bloom for about six weeks. Spring-planted corms bloom for about four weeks, depending on the weather. Once temperatures heat up, the blooms will stop.

In the low desert of Arizona, you can expect blooms to begin in February for fall-planted corms and continue through May for spring-planted corms.

For the longest vase life (10-12 days!) harvest when buds are colored and “squishy like a marshmallow” but not yet open. If they are harvested after opening, the blooms last about a week. Use a floral preservative to encourage a long vase life.

Deadheading plants encourage more blooms.

When blooms finish, and the leaves begin to yellow and die back, cut the foliage off and stop watering. Allow the corms to dry out and go dormant.
If desired, dig up dormant corms and store them in a cool, dry place until it is time to plant next season.
When growing ranunculus for cut flowers, it is best to treat it as an annual and plant new corms each year.

Quick and Easy Flower Arrangements from the Garden

Learn more about growing flowers in this blog post about making flower arrangements from the garden.

Ranunculus Frequently Asked Questions

Can I plant ranunculus corms in the spring?
Yes, you can plant ranunculus corms in the spring if you live in a cooler climate. However, in warmer regions, it’s best to plant them in the fall to take advantage of cooler winter temperatures for optimal growth.

How often should I fertilize ranunculus plants?
If desired, fertilize ranunculus plants every 2-3 weeks during the growing season with a water-soluble flower fertilizer. This can encourage prolific blooming.

What should I do if my ranunculus plants are not blooming?
If your ranunculus plants are not blooming, ensure they get enough sunlight (at least 6 hours per day) and check that the soil is well-drained and not overly wet. Over-fertilizing with nitrogen can also result in lush foliage but few flowers. Adjust care if needed.

Are ranunculus plants invasive?
No, ranunculus plants are not considered invasive. They grow in clumps and can be easily managed in the garden. They do not typically reseed themselves prolifically.

How long do ranunculus flowers last in a vase?
Ranunculus flowers have an excellent vase life, typically lasting 7-10 and up to 12 days if harvested at the right stage (when buds are fully colored and just before opening) and placed in fresh water with proper care.