How to Grow Ranunculus: 5 Tips for More Blooms

Ranunculus are one of my favorite cool-season flowers to grow. The first time I saw their layers of thin, almost paper-like petals, I didn’t think they would grow in the low desert. I’m glad I was wrong.

They grow beautifully here, but timing matters. Ranunculus need cool weather to get established and bloom well. In the low desert, I wait until daytime temperatures are consistently below 90°F (32°C) before planting ranunculus corms.

Once temperatures are right, soaking the corms, planting them correctly, and keeping the soil evenly moist gives them a good start. Here are five things that make the biggest difference.

1. Plant Ranunculus At the Right Time

Arizona Low Desert

The general planting window is October through November, with another opportunity in the spring from February into early March.

But I don’t plant fall corms simply because October has arrived. Wait until daytime temperatures are consistently below 90°F (32°C). I use the same guideline for other cool-season bulbs and corms like anemones, and even garlic. Some years that happens earlier in October, and other years it takes longer.

Fall Planting

Fall planting is my preference in the low desert because it gives the plants a longer growing season and usually a longer bloom period. Corms planted in fall establish through winter and typically begin flowering in late winter or early spring.

Late-Winter Planting

You can also plant ranunculus in February or early March. Because the remaining cool-weather window is shorter, I like to pre-sprout late-winter corms before planting. This gives them a head start.

Cooler Climates

In climates with cold winters, plant ranunculus in spring once severe freezes are no longer a concern. Ranunculus prefer cool growing conditions and begin declining as temperatures rise.

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 Ranunculus Corms Before Planting

Ranunculus grow from dry, claw-shaped corms. Choose large, firm corms when possible. Larger corms have more stored energy and generally produce stronger plants and more flowers. I love the ranunculus bulbs from Renee’s Garden Seeds. Store dry corms in a cool, dry place until planting time. I keep mine in a hall closet. Learn more about ordering bulbs for fall planting in this guide.

How to Soak Ranunculus Corms

Just before planting:

1. Place the dry corms in room-temperature or slightly cool water.
2. Soak for about 3 to 4 hours.
3. Remove them from the water and plant right away.

The corms will swell noticeably as they absorb water. Don’t leave them soaking overnight. Too much time in water can increase the chance of rot.

Do Fall-Planted Corms Have to Be Soaked?

Soaking helps hydrate the corms and can speed up growth, but fall-planted corms can still grow without it.

I’m more likely to pre-sprout corms for a late-winter planting because the remaining cool season is shorter.

How to Pre-Sprout Ranunculus

Pre-sprouting is different from soaking. After soaking the corms:

1. Fill a shallow tray partway with slightly moist potting mix.
2. Place the soaked corms on the mix and cover lightly.
3. Keep the tray in a cool location, ideally around 40–50°F (4–10°C).
4. Keep the mix barely moist, not wet.
5. Check every few days and remove any corms that begin to rot.
6. Plant once you see small white roots developing.

This usually takes around two weeks. I mainly use this method for late-winter planting when I want to give the plants a head start.

3. Plant Ranunculus Correctly

Ranunculus need rich, well-draining soil. Good drainage is especially important because corms can rot if the soil stays wet. Before planting, top-dress or amend with compost if your soil needs it. I wouldn’t automatically add fertilizer at planting if the soil is already healthy and compost-rich.

How to Plant Ranunculus Corms

• Plant corms about 2 to 3 inches (5 to 7.5 cm) deep.
• Space them about 6 inches (15 cm) apart.
• Position the corms with the claws pointing down.
• Cover with soil and water them in.

If using the square foot gardening method, plant four corms per square foot.

Watering After Planting

In dry climates like the low desert, keep the soil lightly and evenly moist while the corms establish. Do not keep the soil saturated. Constantly wet soil is one of the easiest ways to lose ranunculus corms to rot. If you live somewhere with regular fall or winter rain, you may need very little supplemental water.

Growing Ranunculus in Containers

Ranunculus grow well in containers as long as the pot drains well. Use a light, well-draining potting mix and make sure the container has drainage holes. See this bulb container guide for hot climates for planting tips.

For more tips on planting depth, watering, and seasonal timing for ranunculus and other flowering bulbs, visit the Arizona Bulb Growing Guide.

Once ranunculus are growing, you won’t need to do much.

Give Them Plenty of Light

Ranunculus flower best with plenty of sun during cool weather. In the low desert, full sun works well through winter. As spring temperatures rise, plants with some afternoon shade may hold their flowers a little longer.

Keep the Soil Evenly Moist

Water deeply enough to moisten the root zone, then let the soil surface begin to dry before watering again. The goal is consistent moisture without soggy soil.

Feed Lightly

If you planted into healthy soil with compost, ranunculus generally don’t need frequent fertilizer. Container-grown plants may need supplemental feeding because nutrients wash out more quickly. If plants need it, use a balanced fertilizer according to the label rather than feeding automatically every few weeks.

Deadhead Regularly

Cut spent flowers to encourage the plant to keep putting energy into new blooms.

Watch for Rot

Yellowing plants early in the growing season can be a sign of too much water, poor drainage, or root problems. As spring ends, yellowing foliage is normal and signals that the plant is entering dormancy.

Important Safety Note: All parts of ranunculus are toxic if ingested, and the sap may irritate skin. Keep that in mind around children and pets, and consider wearing gloves if the sap bothers your skin.

5. Enjoy Ranunculus Blooms​

Fall-planted ranunculus generally give you the longest bloom season. In my low-desert garden, fall-planted corms can begin flowering in late winter and continue through spring. Late-winter plantings bloom later, but their season is usually shorter because heat arrives sooner. Once temperatures climb, flowering slows and eventually stops.

Harvest Ranunculus for Cut Flowers

Ranunculus make excellent cut flowers.

For the longest vase life, harvest when the buds are fully colored and feel soft, often described as the “marshmallow stage,” but before the flower opens completely. Place cut stems into clean water right away.

Flowers harvested at the right stage can last around a week or longer in a vase. For simple and beautiful flower arrangement ideas, check out how to grow, harvest, and arrange cut flowers.

After Ranunculus Finish Blooming

When flowering ends, leave the foliage until it begins to yellow naturally. Then:

• Stop watering as the foliage dies back.
• Cut off the dry foliage.
• Allow the corms to go dormant.

In climates with mild, dry summers, corms may survive in the ground. In the low desert, our summers are extremely hot, and mine have not reliably returned. I usually treat ranunculus as annuals and plant fresh corms each year.

If you want to save corms, dig them once dormant and store them somewhere cool and dry until the next planting season.