Learn How to Grow Ranunculus Flowers

This popular seasonal cut flower can be a little finnicky to grow at home. However, the stunning ruffled blooms are well worth the effort for determined gardeners who are open to a little experimentation.

Botanical Name: Ranunculus asiaticus
Common Name: Persian buttercup
Bloom Time: Spring
Light Needs: Full sun
Height: 1 to 2 feet
Growth Rate: Moderate

Ranunculus are incredibly trendy spring flowers. The lovely layered buttercup blossoms are often included in floral arrangements featured on social media and in gardening or wedding magazines. Even though the cut flower industry has been experimenting with growing this species for quite a while, it's less familiar in home flower gardens.

These colorful flowering plants are native to the region surrounding the Mediterranean Sea, and in similar Mediterranean climates they send up new shoots and flowers from their roots year after year. However, cold and unpredictable winter weather, extremely warm summer weather, overly wet soils and voracious moles or voles can stop this plant from reliably perennializing in many areas. For motivated gardeners, the hope of stunning jewel-like spring blossoms is well worth the time spent preparing, planting and protecting.

How to Grow Ranunculus

Unless you live in a Mediterranean climate, like much of the west coast and parts of Southwestern states, you'll need to treat ranunculus like an annual or tender perennial plant that will need protection at certain times of the year. Sunny spots that have well-draining soil rich in organic matter are best. Sites with morning sun and afternoon shade may offer some protection from heat for southern gardeners. Ranunculus should grow well in containers, too, which allow gardeners to easily move plants, depending on the current environmental conditions in the garden.

Cut flower farmers usually grow ranunculus from claw-like tubers, and experienced gardeners may feel confident starting their plants this way, too. With that said, ranunculus tubers can be expensive and this can be a temperamental species to grow. Folks who are new to gardening or who are gardening on a budget may want to get some practice growing ranunculus from seed before investing in more pricey tubers.

Robin Yeary, co-owner and operator of Sevier Blumen, has years of experience growing this finnicky species from both seed and tubers at his flower farm in the foothills of the Great Smoky Mountains in Tennessee. According to Yeary, some seasons have been better than others.

"I think a lot of it comes down to perfect situations aligning and that is difficult to do in the outdoor landscape or by just relying on mother nature," Yeary shares, "When you treat them a little bit better, you get a better chance of success."

Sevier Blumen hedges their bets by experimenting with soaking and pre-sprouting tubers, both fall and spring planting, covering tender plants in cold weather, and even growing from seed — all in an effort to grow as many of these beautiful blooms as possible for area florists and farmers markets.

How to Grow Ranunculus from Tubers

The first step in growing ranunculus from tubers is to find a reputable nursery that offers healthy plants. If you buy plants from a box store or garden center, ask if you can take a look at the tubers before purchasing. The tubers should be firm and dry. It's OK if the tubers are a little shriveled up — the main things to look out for are signs of fungal disease or rot. If you choose to order from an online plant nursery, be sure to open and inspect your tubers as soon as they arrive in the mail. Take photos for your records and follow up with the nursery if you have any questions about the health of your plants.

When to Plant Ranunculus Tubers

Dried tubers can be either soaked right away for planting in the fall or stored until late winter. "We've had success planting in the fall," Yeary shares, "but if they start to come up in early warm weather, then they're going to have to be protected." Keep an eye on the forecast and plan to cover with frost cloth, cloches or row covers if freezing temperatures return.

Fall-planted ranunculus tubers are at risk of being eaten by moles or voles. If these critters live in your garden, consider protecting tubers in hardware cloth or wait to plant in early spring so the plants are exposed for a shorter window of time. Planting in the fall can also increase the risk of tubers rotting over the winter. If your garden has poorly drained soils and if you live in an area with especially wet winter weather, you may have better luck planting in early spring.

One major benefit to fall planting is that there's a wider window of time to get your tubers in the ground. On the other hand, spring-planted ranunculus tubers need to be planted when it's not too hot and not too cold, but just right.

Ranunculus grows best when night time temperatures are between 45 and 50 degrees, although they can tolerate dips of cooler weather. If temperatures go below 36 degrees, protect the emerging growth with a frost cloth or cloche. Don't delay planting until later in the spring as this cool-loving plant begins to suffer when evening temperatures are consistently above 60 degrees.

How to Plant Ranunculus Tubers

After removing any unhealthy tubers or trimming out rotten spots, the next step is to soak the tubers in water for between 45 minutes and two hours. "Everyone has their own recommendations, like soaking tubers under running water or with an air bubbler or along with a fungicide treatment," says Yeary, "I, myself, haven't seen much of a difference between these methods."

Next, Yeary recommends pre-sprouting tubers in a cool, dark location (like a cellar or garage) until you see some root and shoot growth. Place the plants with the tubers facing downward into a tray of moist vermiculite or potting soil. After about two weeks, you should see some signs of roots and shoots sprouting.

When it's time to plant, either in the fall or in the spring:

1. Mix some organic matter, like compost or manure, into the garden bed.
2. Dig a small hole, then plant with the crown facing up and the claw-like tubers facing down toward the bottom of the hole. The crown of the plant should be about 2 inches below the soil level. Gently cover with soil and water well.

Plant ranunculus tubers between 4 and 8 inches apart. This will allow some room for air to circulate around the plants and cut down on diseases like botrytis and tuber rot that can come from overcrowded plantings.

How to Grow Ranunculus from Seed

"There's several seed borne varieties that are more for landscapes," says Yeary, "Some of those selections might be easier and less expensive for a home gardener to venture into. Typically, they do flower that first year without a large root system, but you don't get as much of a show."

Persian buttercups need cool, moist conditions to sprout and grow their best. For this reason, it's best to plant your seeds in the fall, then transplant in early spring.

1. Fill a pot or tray with moist potting mix.
2. Gently scatter seeds on the soil surface before lightly covering with more potting mix.
3. Place the container in an unheated garage or sunroom, and gently mist every few days. It might take a few weeks for the seedlings to sprout, but when they emerge, move them to a bright spot like next to a sunny window or under a grow light. After about two or three weeks, ranunculus seedlings will have two pairs of leaves — first, a pair of rounded "seed leaves" and a second pair of "true leaves" higher up on the stem. When your seedlings have their true leaves, that means they're ready to move to their own pot.
4. Gently grasp one of the true leaves (not the stem), and use a pencil or popsicle stick to carefully lift the roots from the potting mix.
5. Lightly tamp down the potting soil around the seedling in its new container, then water until it begins to drip out of the drainage holes at the bottom of the pot.
6. Wait until the danger of frost has passed before planting in the garden or moving containers outside.

Check with your state extension service to learn when the average last frost date for your region is. If the forecast calls for cold, wet weather, make sure the site has good drainage and consider covering with a cloche or row cover. While ranunculus leaves may tolerate a late cold snap, one thing they won't put up with is soggy, chilly roots.

How to Harvest Ranunculus as a Cut Flower

Ranunculus blooms are a joy in the garden or in a vase. If you choose to snip some stems to share with friends or bring indoors, here are a few tips to get your ranunculus flowers to last as long as possible in a vase.

1. Try to cut your flowers in the cool of the morning.
2. Use sharp, clean scissors, hand pruners, or flower snips to cut the base of the stem, above where most of the foliage is growing near the bottom of the plant.
3. Immediately place the stem in a bucket or jar of clean water or water with floral preservative, and bring indoors as soon as you're finished harvesting.

Yeary recommends waiting until the flower is completely open before bringing a stem inside. "Ranunculus flowers open in the morning and at night they close back up," says Yeary. "You want them to open and close several times and be pretty good and open before you harvest them." On the other hand, for a longer vase life, you can pick stems that have buds that are just about to open and are showing some of the petal color in the opening center.

Depending on the environment, you can expect between one and three weeks of flowers before the plants begin to decline. The foliage will start to turn yellow as the plant enters dormancy when evening temperatures are consistently above 60 degrees. You may be able to lift the tubers and store in the garage to plant for next year after the plant has completely died to the ground. However, most gardeners treat ranunculus like an annual, enjoying the blooms while they're in season and ordering new tubers or planting new seeds the following season.